Global climate change is having long-term impacts on the geographic distribution of forest species. However, the response of vertical belts of mountain forests to climate change is still little known. The vertical dis...Global climate change is having long-term impacts on the geographic distribution of forest species. However, the response of vertical belts of mountain forests to climate change is still little known. The vertical distribution of forest vegetation(vertical vegetation belt) on Gongga Mountain in Southwest China has been monitored for 30 years. The forest alternation of the vertical vegetation belt under different climate conditions was simulated by using a mathematical model GFSM(the Gongga Forest Succession Model). Three possible Intergovernmental Panel on Climate Change(IPCC) climate scenarios(increase of air temperature and precipitation by 1.8℃/5%, 2.8℃/10% and 3.4℃/15% for B_1, A_1B and A_2 scenarios, respectively) were chosen to reflect lower, medium and higher changes of global climate. The vertical belts of mountainous vegetation will shift upward by approximately 300 m, 500 m and 600 m in the B_1, A_1B and A_2 scenarios, respectively, according to the simulated results. Thus, the alpine tree-line will move to a higher altitude. The simulation also demonstrated that, in a changing climate, the shift in the vegetation community will be a slow and extended process characterized by two main phases. During the initial phase, trees of the forest community degrade or die, owing to an inability to adapt to a warmer climate. This results in modest environment for the introduction of opportunistic species, consequently, the vegetation with new dominant tree species becomes predominant in the space vacated by the dead trees at the expense of previously dominated original trees as the succession succeed and climate change advance. Hence, the global climate change would dramatically change forest communities and tree species in mountainous regions because that the new forest community can grow only through the death of the original tree. Results indicated that climate change will cause the change of distribution and composition of forest communities on Gongga Mountain, and this change may enhance as the intensity of climate change increases. As a result, the alternation of death and rebirth would finally result in intensive landscape changes, and may strongly affect the eco-environment of mountainous regions.展开更多
As a result of socio-economic changes and land abandonment,the main ecological driver of the Carpathian landscape is the progression of the natural forest succession process.Thus,aspects of this process have become wo...As a result of socio-economic changes and land abandonment,the main ecological driver of the Carpathian landscape is the progression of the natural forest succession process.Thus,aspects of this process have become worthy of attention,especially in the context of carbon sequestration and the management of protected areas.Soil processes,especially within the topsoil,are some of the most susceptible to change,due to the accumulation of organic matter during such land-use transformations.The purposes of this study were to investigate the differences in topsoil development using the A Horizon Development Index(ADI)and to study the composition of humic substances and advanced organic matter humification in different land-use areas in selected Carpathian national parks,i.e.Bieszczady,Magura and Pieniny National Parks in southern Poland.Additionally,a goal of this study was to compare the ADI and the spectroscopic coefficients of humic substances as indicators of the degree of humus horizon shaping as well as advanced organic matter humification.In total,ten transects were selected,each consisting of three different land-use areas:semi-natural meadow,successional forest and old-growth forest.Soil colour was determined in fresh and air-dried samples using the Munsell colour chart.In air-dried soil samples p H,soil texture,total organic carbon and total nitrogen were measured.Humic substances were extracted and further characterized by UV-VIS spectroscopy.The ADI confirmed the influence of natural forest succession on soil colour darkening and the development of the uppermost soil layer.Spectroscopic analyses of humic substances showed two different patterns depending on soil depth.In the 0–10 cm layer,natural forest succession reduced the rate of the humification process and decreased the degree of maturity of fulvic acids;in the 10–20 cm layer,it led to an increase in the rate of the humification process and a decrease in the content of humic and fulvic acids at the beginning of the transformation.The comparison of two different indicators of soil development–the ADI and the spectroscopic coefficients of humic substances(Q_(4/6),Q_(2/4),Q_(2/3),Δlog K)–indicated that these indexes are based on different features of soil and cannot be used interchangeably.展开更多
Background:As a structurally and functionally important component in forest ecosystems,plant debris plays a crucial role in the global carbon cycle.Although it is well known that plant debris stocks vary greatly with ...Background:As a structurally and functionally important component in forest ecosystems,plant debris plays a crucial role in the global carbon cycle.Although it is well known that plant debris stocks vary greatly with tree species composition,forest type,forest origin,and stand age,simultaneous investigation on the changes in woody and non-woody debris biomass and their carbon stock with forest succession has not been reported.Therefore,woody and non-woody debris and carbon stocks were investigated across a subalpine forest successional gradient in Wanglang National Nature Reserve on the eastern Qinghai-Tibet Plateau.Results:Plant debris ranged from 25.19 to 82.89 Mg∙ha−1 and showed a global increasing tendency across the subalpine forest successional series except for decreasing at the S4 successional stage.Accordingly,the ratios of woody to non-woody debris stocks ranged from 26.58 to 208.89,and the highest and lowest ratios of woody to non-woody debris stocks were respectively observed in mid-successional coniferous forest and shrub forest,implying that woody debris dominates the plant debris.In particular,the ratios of coarse to fine woody debris stocks varied greatly with the successional stage,and the highest and lowest ratios were found in later and earlier successional subalpine forests,respectively.Furthermore,the woody debris stock varied greatly with diameter size,and larger diameter woody debris dominated the plant debris.Correspondingly,the carbon stock of plant debris ranged from 10.30 to 38.87 Mg∙ha−1 across the successional series,and the highest and lowest values were observed in the mid-coniferous stage and shrub forest stage,respectively.Most importantly,the carbon stored in coarse woody debris in later successional forests was four times higher than in earlier successional forests.Conclusions:The stock and role of woody debris,particularly coarse woody debris,varied greatly with the forest successional stage and dominated the carbon cycle in the subalpine forest ecosystem.Thus,preserving coarse woody debris is a critical strategy for sustainable forest management.展开更多
There is an increasing interest in restoring degraded forests,which occupy half of the forest areas.Among the forms of restoration,passive restoration,which involves the elimination of degrading factors and the free e...There is an increasing interest in restoring degraded forests,which occupy half of the forest areas.Among the forms of restoration,passive restoration,which involves the elimination of degrading factors and the free evolution of natural dynamics by applying minimal or no management,is gaining attention.Natural dynamics is difficult to predict due to the influence of multiple interacting factors such as climatic and edaphic conditions,composition and abundance of species,and the successional character of these species.Here,we study the natural dynamics of a mixed forest located in central Spain,which maintained an open forest structure,due to intensive use,until grazing and cutting were banned in the 1960s.The most frequent woody species in this forest are Fagus sylvatica,Quercus petraea,Quercus pyrenaica,Ilex aquifolium,Sorbus aucuparia,Sorbus aria and Prunus avium,with contrasting shade and drought tolerance.These species are common in temperate European deciduous forest and are found here near their southern distribution limit,except for Q.pyrenaica.In order to analyze forest dynamics and composition,three inventories were carried out in 1994,2005 and 2015.Our results show that,despite the Mediterranean influence,the natural dynamics of this forest has been mainly determined by different levels of shade tolerance.After the abandonment of grazing and cutting,Q.pyrenaica expanded rapidly due to its lower shade tolerance,whereas after canopy closure and forest densification,shade-tolerant species gained ground,particularly F.sylvatica,despite its lower drought and late-frost tolerance.If the current dynamics continue,F.sylvatica will overtake the rest of the species,which will be relegated to sites with shallow soils and steep slopes.Simultaneously,all the multi-centennial beech trees,which are undergoing a rapid mortality and decline process,will disappear.展开更多
The main species composition drivers in temperate deciduous forests are environmental conditions, a stand?s age and the site history, e.g., the succession stage and past land use, as well as disturbance regime and cur...The main species composition drivers in temperate deciduous forests are environmental conditions, a stand?s age and the site history, e.g., the succession stage and past land use, as well as disturbance regime and current management. We compared plant species diversity and composition in late successional and ancient forests, cooccurring on the same small river island applying species accumulation curves and nonmetric multidimensional scaling, respectively. Given the island?s geomorphological characteristics, we expected these to be very similar before human intervention in the past. The forests experienced differing disturbance regimes in the past, while over the last 30 years, human intervention has been the same and reduced to a minimum. The ancient forest in this study had two major characteristics defining it as old, mature forest: continuity of presence for more than 200years and specific composition. The late successional forest experienced major disturbance in the 20th century and was allowed natural regeneration by bordering on the ancient forest, representing a potential species pool,and by decades of minimum human intervention. Our results showed that, even though there was no difference in species richness, we could still detect differences between the forests, particularly in the abundance and species composition of the understorey, among which geophytes had the most indicative importance. To make our results useful on a broader scale, we composed from the literature a species list of plants indicative for ancient forest and tested its application. These results are important for distinguishing between old and mature secondary stands and particularly for identifying old forest stands, which should be conserved and, in the case of fragmented landscapes, included in a network connecting forest fragments.展开更多
Aims We investigated shifts in community-weighted mean traits(CWm)of 14 leaf functional traits along a secondary successional series in an evergreen broadleaf forest in subtropical southeast China.most of the investig...Aims We investigated shifts in community-weighted mean traits(CWm)of 14 leaf functional traits along a secondary successional series in an evergreen broadleaf forest in subtropical southeast China.most of the investigated traits have been reported to affect litter decomposition in previous studies.We asked whether changes in CWms along secondary succession followed similar patterns for all investigated traits and whether the shifts in CWm indicated a change in resource use strategy along the successional gradient.using community decomposition rates(k-rates)estimated from annual lit-ter production and standing litter biomass,we asked whether the dynamics of litter decomposition were related to changes in leaf functional traits along the successional series.Methods twenty-seven plots were examined for shifts in leaf CWm traits as well as in k-rates along a series of secondary forest succession cov-ered in the framework of the bEF-China project.We investigated whether the changes in CWms followed similar patterns for all traits with ongoing succession.three alternative linear models were used to reveal the general patterns of shifts in CWm trait values.moreover,multiple regression analysis was applied to investigate whether there were causal relationships between the changes in leaf functional traits and the dynamics of litter decomposition along secondary succession.We furthermore assessed which traits had the highest impact on community litter decomposition.Important Findingsshifts in CWm values generally followed logarithmic patterns for all investigated traits,whereas community k-rates remained stable along the successional gradient.In summary,the shifts in CWm values indicate a change in community resource use strategy from high nutrient acquisition to nutrient retention with ongoing succession.stands with higher CWm values of traits related to nutrient acquisition had also higher CWm values of traits related to chemical resistance,whereas stands with higher CWm values of traits related to nutrient retention exhibited higher CWm values in leaf physical defense.moreover,high values in CWm values related to nutritional quality(such as high leaf phosphorus concentrations)were found to promote com-munity k-rates,whereas high values in physical or chemical defense traits(such as high contents in polyphenols or high leaf toughness)decreased litter decomposition rates.In consequence,litter decom-position,which was simultaneously affected by these characteristics,did not change significantly along succession.our findings show that leaf decomposition within the investigated communities is dependent on the interplay of several traits and is a result from interactions of traits that affect decomposition in opposing directions.展开更多
Aims Assessing the role of a dominant native bamboo species on tree species diversity and structure in the medium term.Methods Over a 7-year period,we studied the natural regeneration of two dominant forest types in S...Aims Assessing the role of a dominant native bamboo species on tree species diversity and structure in the medium term.Methods Over a 7-year period,we studied the natural regeneration of two dominant forest types in Southern Brazil(Araucaria Forest or AF;Bamboo Forest or BF)after a bamboo(Merostachys skvortzovii Send.)die-off between 2004 and 2006.The study was carried out in the Embrapa Research Station in Cacador,Santa Catarina State,Brazil.Important Findings The die-off provided ideal conditions for the establishment of several species and it kickstarted forest succession dynamics,which in turn affected regeneration diversity.Tree species richness was relatively stable with a transitory increase between 2007 and 2014 in both AF and BF.However,species richness rose in BF because of a relative increase in abundance of some species(especially late and secondary species)while a plunge in some pioneer species drove an increase in diversity.Overall,we found that BF has a lower diversity of recruits and that density declined over time,while AF is more diverse,with a more stable density.In BF,the bamboo die-off created optimal conditions for initial regeneration development(mainly fast-growing pioneer trees),which quickly transited to higher size classes.Yet,after this initial stage of pioneer recruitment,the number of recruits dropped followed by a virtual absence of growth regardless of the species group as a result of a quick bamboo reestablishment.As bamboo recreated a dense understory it reduced species diversity to original levels,suggesting a self-maintaining cycle that halts forest succession.On the other hand,the bamboo die-off had little impact on AF where a slow recruitment process typical of old-growth forests was observed.The results indicate that the die-off event had a temporary effect on species diversity i.e.restricted to forests where bamboos are dominant in a similar process described in other southern South American forests.As the first study to observe the medium-term forest dynamics related to bamboo die-off,we can conclude that when being dominant,native bamboos can hinder forest regeneration,maintaining lower levels of diversity and arresting forest succession that lasts well beyond the short-term,post-die-off effects.Many forest fragments in the region are dominated by bamboos,thus their potential for conservation is at risk and requires appropriate management.展开更多
Background: Tropical forests play an important role in the global carbon(C) cycle.However, tropical montane forests have been studied less than tropical lowland forests, and their role in carbon storage is not well...Background: Tropical forests play an important role in the global carbon(C) cycle.However, tropical montane forests have been studied less than tropical lowland forests, and their role in carbon storage is not well understood.Montane forests are highly endangered due to logging, land-use and climate change.Our objective was to analyse how the carbon balance changes during forest succession.Methods: In this study, we used a method to estimate local carbon balances that combined forest inventory data with process-based forest models.We utilised such a forest model to study the carbon balance of a tropical montane forest in South Ecuador, comparing two topographical slope positions(ravines and lower slopes vs upper slopes and ridges).Results: The simulation results showed that the forest acts as a carbon sink with a maximum net ecosystem exchange(NEE) of 9.3 Mg C?(ha?yr)-1during its early successional stage(0–100 years).In the late successional stage, the simulated NEE fluctuated around zero and had a variation of 0.77 Mg C?(ha?yr)–1.The simulated variability of the NEE was within the range of the field data.We discovered several forest attributes(e.g., basal area or the relative amount of pioneer trees) that can serve as predictors for NEE for young forest stands(0–100 years) but not for those in the late successional stage(500–1,000 years).In case of young forest stands these correlations are high, especially between stand basal area and NEE.Conclusion: In this study, we used an Ecuadorian study site as an example of how to successfully link a forest model with forest inventory data, for estimating stem-diameter distributions, biomass and aboveground net primary productivity.To conclude, this study shows that process-based forest models can be used to investigate the carbon balance of tropical montane forests.With this model it is possible to find hidden relationships between forest attributes and forest carbon fluxes.These relationships promote a better understanding of the role of tropical montane forests in the context of global carbon cycle, which in future will become more relevant to a society under global change.展开更多
In cold or alpine areas of northern China,birch forests and larch forests are the two primary forest types.These forests are also characteristic of a south branch of boreal forests in Asia.Some ecologists argue that l...In cold or alpine areas of northern China,birch forests and larch forests are the two primary forest types.These forests are also characteristic of a south branch of boreal forests in Asia.Some ecologists argue that larch forests can replace birch forests,but this still remains a question due to fragmentary or short observations.The ecotone between a larch forest patch and a birch forest patch is the arena in which the two species interplay and compete with each other,and studies of these areas are meaningful to understanding forest succession.In the alpine area of the Baihuashan Reserve,northern China,we sampled a larch-birch forest ecotone with eight plots in four transects and then analyzed population structures of larches and birches.The results show that the edges of the larch forest patch are composed of many larch saplings or young trees,but the edges of the birch forest patch are mainly composed of old birches.Across the ecotone,the larches,on average,are taller than the birches.These facts suggest that larch saplings can permeate into birch forest patches,probably by seed dispersal,germination,success-ful competition and growth,but birch saplings cannot permeate into larch forest patches.Therefore,on the ecotone,larch forest patches can steadily expand by unceasing permeation into birch forest patches,whereas birch forest patches progressively recede due to ultimate death of the old and poor recruitment of the young.Larch forest patches replace birch forest patches in a stepwise manner,causing succession from birch forests to larch forests.This study not only confirms that larch forests can naturally replace birch forests,but also introduces a simple and reliable method,employing spatial hints,to study forest succession.Additionally,the findings are of benefit to cultivation or development of larch forests in cold or alpine areas of the North Temperate Zone,which can be a huge carbon sink.展开更多
As forests in neotropical regions,particularly in developing countries,are devastated,interventions to restore biodiversity and its ecological functions are needed.Rural producers have thus been encouraged to grow tre...As forests in neotropical regions,particularly in developing countries,are devastated,interventions to restore biodiversity and its ecological functions are needed.Rural producers have thus been encouraged to grow trees for wood production as an economic activity.The objective of this study was to quantify the increment of wood density of four forest species from different successional classes of a mixed system of restoration in a neotropical forest in Brazil.Tree discs were sampled at breast height and analyzed radially by X-ray densitometry to obtain apparent density and basic density.Three trees each of a species from the pioneer,early and late secondary successional stages and of the dominant species in the climax community.The radial profiles indicated increasing density from the pith to bark of trunks,except for some variations due to wood defects and growth.Average density was 0.576 g cm^(-3),0.655 g cm^(-3),0.706 g cm^(-3)and 0.775 g cm^(-3),respectively,for Peltophorum dubium,Schinus terebinthifolius,Cariniana estrellensis and Hymenaea courbaril.Radial profiles indicated higher amplitudes in the apparent densities for slow-growing species.X-ray densitometry generated parameters such as minimum,average and maximum densities,and radial density variations.These parameters are important for understanding the ecological functional role of successional classes of the Atlantic Forest from the Neotropical region.展开更多
Subalpine dark coniferous forests in the western Sichuan Province of China play an important role in the hydrological processes in the upper reaches of the Yangtze River. Second-growth forests, with different stand su...Subalpine dark coniferous forests in the western Sichuan Province of China play an important role in the hydrological processes in the upper reaches of the Yangtze River. Second-growth forests, with different stand successional stages, have developed as a result of logging over the past 50 years. Forest cover and stand structure changed greatly with concomitant degradation of forest ecosystem functions. To understand how the stand structures of the second-growth forests change during the stand succession process, we analyzed stand structure characteristics and an old-growth state index of the bamboo and moss-forest types. We found that stand structure at the young successional stage featured one-third of the structure characteristics of the old-growth dark coniferous forests,while the structure of the medium-aged stage had reached half the structure of the old-growth state. The two forest types were similar in the rate of development at the young successional stage but differed at the medium-aged stage;the moss-forest type had more advanced development than the bamboo-forest type at the medium-aged successional stage.展开更多
Background: The early stage of forest succession following disturbance is characterized by a shift in songbird composition as well as increased avian richness due to increased herbaceous growth in the forest understor...Background: The early stage of forest succession following disturbance is characterized by a shift in songbird composition as well as increased avian richness due to increased herbaceous growth in the forest understory. However, regeneration of woody species eventually outcompetes the herbaceous understory, subsequently shifting vegetation communities and decreasing availability of vital foraging and nesting cover for disturbance-dependent birds, ultimately resulting in their displacement. These early stages following forest disturbance, which are declining throughout the eastern United States, are ephemeral in nature and birds depend on such disturbances for nesting and other purposes throughout their lives.Methods: We investigated the use of a two-stage shelterwood method to manage long-term persistence of seven early successional songbirds over a 13-year period in an upland hardwood forest within the southern end of the midCumberland Plateau in the eastern United States.Results: Canopy and midstory gaps created after initial harvest were quickly exploited by tree growth and canopy cover returned to these areas, accelerating the displacement of early-successional species. Woody stem densities increased substantially following stage two harvest as advanced tree regeneration combined with the re-opening of the overstory layer increased resource competition for early-successional plants in the understory. Carolina Wren(Thryothorus ludovicianus), Eastern Towhee(Pipilo erythrophthalmus), Indigo Bunting(Passerina cyanea), and Yellowbreasted Chat(Icteria virens) were characterized by immediate increases following initial harvest in 2001; while the American Goldfinch(Spinus tristis), Prairie Warbler(Setophaga discolor), and White-eyed Vireo(Vireo griseus) did not show an immediate response. Stage two harvest in 2011 rejuvenated vegetation which benefitted focal species, with six of seven species showing increases in densities between 2010 and 2012.Conclusion: The two-stage shelterwood method created conditions advantageous to early-successional birds by helping to re-establish understory vegetation through periodic disturbance to the canopy layer. This method provides evidence that early-successional species can be managed long-term(> 15 years) while using relatively small spatial disturbance through the two-stage shelterwood method.展开更多
Periodical cicadas(Magicicada spp.)are endemic to deciduous forests in the eastern United States.In successional forests,they must partition resources such as host trees to coexist.We measured tree size,emergence hole...Periodical cicadas(Magicicada spp.)are endemic to deciduous forests in the eastern United States.In successional forests,they must partition resources such as host trees to coexist.We measured tree size,emergence holes,oviposition scar bundles,and chorusing center abundances of Magicicada species on 12 common tree species in a deciduous forest to understand host-tree use.We predicted that the abundance of periodical cicadas and use of specific host-tree species would change depending on the Magicicada species and tree life stage.We considered the size of the tree(diameter at breast height)as a covariate to control for tree size and collected eggs for a greenhouse experiment to assess whether nymphs prefer to feed on Quercus rubra or Acer saccharum.More emergence holes were found below Quercus species than any other tree species.The abundance of periodical cicadas on host trees used for chorusing centers varied depending on the Magicicada species,but were most abundant on Quercus species.Oviposition scar bundles were also more frequent on Quercus.More nymphs were found on Quercus than Acer in the nymph preference study.Though periodical cicadas used Quercus hosts more than other tree species,their abundances on different host tree sizes and species differed significantly.Periodical cicada species may use specific host species and life stages as a way to partition resources and minimize competition among the Magicicada species during emergence years.展开更多
Background:Old-growth forests are irreplaceable with respect to climate change mitigation and have considerable carbon(C)sink potential in soils.However,the relationship between the soil organic carbon(SOC)turnover ra...Background:Old-growth forests are irreplaceable with respect to climate change mitigation and have considerable carbon(C)sink potential in soils.However,the relationship between the soil organic carbon(SOC)turnover rate and forest development is poorly understood,which hinders our ability to assess the C sequestration capacity of soil in old-growth forests.Methods:In this study,we evaluated the SOC turnover rate by calculating the isotopic enrichment factor β(defined as the slope of the regression between ^(13)C natural abundance and log-transformed C concentrations)along 0-30 cm soil profiles in three successional forests in subtropical China.A lower β(steeper slope)is associated with a higher turnover rate.The three forests were a 60-year-old P.massoniana forest(PF),a 100-year-old coniferous and broadleaved mixed forest(MF),and a 400-year-old monsoon evergreen broadleaved forest(BF).We also analyzed the soil physicochemical properties in these forests to examine the dynamics of SOC turnover during forest succession and the main regulators.Results:The β value for the upper 30-cm soils in the BF was significantly(p<0.05)higher than that in the PF,in addition to the SOC stock,although there were nonsignificant differences between the BF and MF.The β value was significantly(p<0.05)positively correlated with the soil recalcitrance index,total nitrogen,and available nitrogen contents but was significantly(p<0.01)negatively correlated with soil pH.Conclusions:Our results demonstrate that SOC has lower turnover rates in old-growth forests,accompanied by higher soil chemical recalcitrance,nitrogen status,and lower soil pH.This finding helps to elucidate the mechanism underlying C sequestration in old-growth forest soils,and emphasizes the important value of old-growth forests among global C sinks.展开更多
Background: Schima genus of Theaceae is confined to subtropics and tropics of South, East and Southeast Asia.Thirteen species of Schima are distributed in subtropical China. Many of them appear as dominant canopy spec...Background: Schima genus of Theaceae is confined to subtropics and tropics of South, East and Southeast Asia.Thirteen species of Schima are distributed in subtropical China. Many of them appear as dominant canopy species in the subtropical forests. To date, Schima species richness distribution patterns of China have remained unknown.Meanwhile, there has been a longtime debate as to whether forests dominated by Schima species are early or late successional forests. We aim to clarify Schima species richness patterns and these species' roles in the forest succession and regeneration dynamics of the subtropical ecosystem in Yunnan Province, China.Method: We mapped Schima species richness distribution patterns in China. Based on 71 vegetation plots, we analyzed forest characteristics, population structure, and regeneration dynamics of Schima species in Yunnan.Results: Yunnan was found to harbor the greatest richness and the highest rarity-weighted richness of Schima species in the subtropical regions of China. We classified five primary and six secondary forest types containing Schima species as one of dominants. Yunnan had the high floristic diversity and varying stand structure of forests containing Schima species. The Schima species studied generally had a sporadic regeneration type and a long lifespan. Four species(Schima argentea, Schima villosa, Schima sinensis, Schima sericans) were shade-intolerant. But three species(Schima noronhae, Schima khasiana and Schima wallichii) were considered as bi-modal type species having shade-intolerant and shade-tolerant traits. Schima noronhae was seen to be a top dominant in late successional forests, while S. wallichii was found as a top-dominant in early or middle or late successional forests. S.khasiana, Schima villosa, Schima sinensis usually appeared as a top dominant in early or middle successional secondary forests, though they also presented as a second dominant in late-successional forests. Schima argentea and Schima sericans dominated only in the early or middle/seral successional forests. Schima species' regeneration establishment depended mainly on forest canopy gap formation through moderate human and natural disturbances.Conclusions: Yunnan has high species richness and rarity-weighted richness of Schima. Both moderate human and natural disturbances have provided regeneration niches for Schima species. Some of the Schima species studied as a second dominant(rare as the top-dominant) present in the late-successional forests. Some of them are more often as the top-dominant in early or middle successional forests, where as time goes by the dominance of Schima species would be replaced by their associated dominant taxa such as Castanopsis species.展开更多
Background:Conceptual models of forest dynamics are powerful cognitive tools,which are indispensable for communicating ecological ideas and knowledge,and in developing strategic approaches and setting targets for for...Background:Conceptual models of forest dynamics are powerful cognitive tools,which are indispensable for communicating ecological ideas and knowledge,and in developing strategic approaches and setting targets for forest conservation,restoration and sustainable management.Forest development through time is conventionally described as a directional,or "linear",and predictable sequence of stages from "bare ground" to old forest representing the "climax-state".However,this simple view is incompatible with the current knowledge and understanding of intrinsic variability of forest dynamics.Hypothesis:Overly simple conceptual models of forest dynamics easily become transformed into biased mental models of how forests naturally develop and what kind of structures they display.To be able to communicate the essential features and diversity of forest dynamics,comprehensive conceptual models are needed.For this end,Kuuluvainen(2009) suggested a relatively simple conceptual model of forest dynamics,which separates three major modes of forest dynamics,and incorporates state changes and transitions between the forest dynamics modes depending on changes in disturbance regime.Conclusions:Conceptual models of forest dynamics should be comprehensive enough to incorporate both longterm directional change and short-term cyclic forest dynamics,as well as transitions from one dynamics mode to another depending on changes in the driving disturbance regime type.Models that capture such essential features of forest dynamics are indispensable for educational purposes,in setting reference conditions and in developing methods in forest conservation,restoration and ecosystem management.展开更多
Background: In recent decades, native Araucaria forests in Brazil have become fragmented due to the conversion of forest to agricultural lands and commercial tree plantations. Consequently, the forest dynamics in thi...Background: In recent decades, native Araucaria forests in Brazil have become fragmented due to the conversion of forest to agricultural lands and commercial tree plantations. Consequently, the forest dynamics in this forest type have been poorly investigated, as most fragments are poorly structured in terms of tree size and diversity. Methods; We developed a distance-independent individual tree-growth model to simulate the forest dynamics in a native Araucaria forest located predominantly in southern Brazil. The data were derived from 25 contiguous plots (1 ha) established in a protected area left undisturbed for the past 70 years. The plots were measured at 3-year intervals from their establishment in 2002. All trees above a l O-cm diameter at breast height were tagged, identified as to species, and measured. Because this forest type comprises hundreds of tree species, we clustered them into six ecological groups: understory, subcanopy, upper canopy shade-tolerant, upper canopy light-demanding, pioneer, and emergent. The diameter increment, survival, and recruitment sub-models were fitted for each species group, and parameters were implemented in a simulation software to project the forest dynamics. The growth model was validated using independent data collected from another research area of the same forest type. To simulate the forest dynamics, we projected the species group and stand basal areas for 50 years under three different stand-density conditions: low, average, and high. Results: Emergent species tended to grow in basal area, irrespective of the forest density conditions. Conversely, shade-tolerant species tended to decline over the years. Under low-density conditions, the model showed a growth tendency for the stand basal area, while under average-density conditions, forest growth tended to stabilize within 30 years. Under high-density conditions, the model indicated a decline in the stand basal area from the onset of the simulation, suggesting that under these conditions, the forest has already reached its maximum-stock capacity. Conclusions: The model validation using independent data indicated close agreement between the observed and estimated values, suggesting the model is consistent in projecting species-group and stand growth. The methodology used in this study for developing the growth model should be tested in other species-rich forests.展开更多
The Atlantic Forest is among the 35 hotspots on the planet, and yet few floristic or structural studies have been conducted on mature forest fragments of that biome in Brazil. In view of this knowledge gap and of the ...The Atlantic Forest is among the 35 hotspots on the planet, and yet few floristic or structural studies have been conducted on mature forest fragments of that biome in Brazil. In view of this knowledge gap and of the need to further comprehend the importance of conserving mature forests, we surveyed the arboreal component of three little-altered forest remnants from the S?o Paulo metropolitan region (SPMR), southeastern Brazil, and compared our data with the one from other phytosociological studies performed in the region. Mature forests showed a different floristic composition from one of young forests. Overall, the former has a higher number and percentage of threatened and endemic species than the latter, and also a higher exclusivity of occurrence of threatened species. In areas up to twice as smaller, mature forests have 1.5 to 4.3 times more endemic species to the Atlantic Forest and up to 9 times more species threatened with extinction than young forests. These facts, along with the scarcity of remnants of mature forests, led us to consider such forests as hotspots within the Atlantic Forest hotspot in the SPMR, as well as to categorize them as of high relevance for conservation.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos. 41671016 and 41671262)
文摘Global climate change is having long-term impacts on the geographic distribution of forest species. However, the response of vertical belts of mountain forests to climate change is still little known. The vertical distribution of forest vegetation(vertical vegetation belt) on Gongga Mountain in Southwest China has been monitored for 30 years. The forest alternation of the vertical vegetation belt under different climate conditions was simulated by using a mathematical model GFSM(the Gongga Forest Succession Model). Three possible Intergovernmental Panel on Climate Change(IPCC) climate scenarios(increase of air temperature and precipitation by 1.8℃/5%, 2.8℃/10% and 3.4℃/15% for B_1, A_1B and A_2 scenarios, respectively) were chosen to reflect lower, medium and higher changes of global climate. The vertical belts of mountainous vegetation will shift upward by approximately 300 m, 500 m and 600 m in the B_1, A_1B and A_2 scenarios, respectively, according to the simulated results. Thus, the alpine tree-line will move to a higher altitude. The simulation also demonstrated that, in a changing climate, the shift in the vegetation community will be a slow and extended process characterized by two main phases. During the initial phase, trees of the forest community degrade or die, owing to an inability to adapt to a warmer climate. This results in modest environment for the introduction of opportunistic species, consequently, the vegetation with new dominant tree species becomes predominant in the space vacated by the dead trees at the expense of previously dominated original trees as the succession succeed and climate change advance. Hence, the global climate change would dramatically change forest communities and tree species in mountainous regions because that the new forest community can grow only through the death of the original tree. Results indicated that climate change will cause the change of distribution and composition of forest communities on Gongga Mountain, and this change may enhance as the intensity of climate change increases. As a result, the alternation of death and rebirth would finally result in intensive landscape changes, and may strongly affect the eco-environment of mountainous regions.
基金supported by Statutory financial support of Ministry of Science and Higher Education RP Department of Soil Science and Agrophysics[010013D011 in 2021]University of Agriculture in Krakow。
文摘As a result of socio-economic changes and land abandonment,the main ecological driver of the Carpathian landscape is the progression of the natural forest succession process.Thus,aspects of this process have become worthy of attention,especially in the context of carbon sequestration and the management of protected areas.Soil processes,especially within the topsoil,are some of the most susceptible to change,due to the accumulation of organic matter during such land-use transformations.The purposes of this study were to investigate the differences in topsoil development using the A Horizon Development Index(ADI)and to study the composition of humic substances and advanced organic matter humification in different land-use areas in selected Carpathian national parks,i.e.Bieszczady,Magura and Pieniny National Parks in southern Poland.Additionally,a goal of this study was to compare the ADI and the spectroscopic coefficients of humic substances as indicators of the degree of humus horizon shaping as well as advanced organic matter humification.In total,ten transects were selected,each consisting of three different land-use areas:semi-natural meadow,successional forest and old-growth forest.Soil colour was determined in fresh and air-dried samples using the Munsell colour chart.In air-dried soil samples p H,soil texture,total organic carbon and total nitrogen were measured.Humic substances were extracted and further characterized by UV-VIS spectroscopy.The ADI confirmed the influence of natural forest succession on soil colour darkening and the development of the uppermost soil layer.Spectroscopic analyses of humic substances showed two different patterns depending on soil depth.In the 0–10 cm layer,natural forest succession reduced the rate of the humification process and decreased the degree of maturity of fulvic acids;in the 10–20 cm layer,it led to an increase in the rate of the humification process and a decrease in the content of humic and fulvic acids at the beginning of the transformation.The comparison of two different indicators of soil development–the ADI and the spectroscopic coefficients of humic substances(Q_(4/6),Q_(2/4),Q_(2/3),Δlog K)–indicated that these indexes are based on different features of soil and cannot be used interchangeably.
基金supported by the National Nature Science Foundation of China(32071554,31570445).
文摘Background:As a structurally and functionally important component in forest ecosystems,plant debris plays a crucial role in the global carbon cycle.Although it is well known that plant debris stocks vary greatly with tree species composition,forest type,forest origin,and stand age,simultaneous investigation on the changes in woody and non-woody debris biomass and their carbon stock with forest succession has not been reported.Therefore,woody and non-woody debris and carbon stocks were investigated across a subalpine forest successional gradient in Wanglang National Nature Reserve on the eastern Qinghai-Tibet Plateau.Results:Plant debris ranged from 25.19 to 82.89 Mg∙ha−1 and showed a global increasing tendency across the subalpine forest successional series except for decreasing at the S4 successional stage.Accordingly,the ratios of woody to non-woody debris stocks ranged from 26.58 to 208.89,and the highest and lowest ratios of woody to non-woody debris stocks were respectively observed in mid-successional coniferous forest and shrub forest,implying that woody debris dominates the plant debris.In particular,the ratios of coarse to fine woody debris stocks varied greatly with the successional stage,and the highest and lowest ratios were found in later and earlier successional subalpine forests,respectively.Furthermore,the woody debris stock varied greatly with diameter size,and larger diameter woody debris dominated the plant debris.Correspondingly,the carbon stock of plant debris ranged from 10.30 to 38.87 Mg∙ha−1 across the successional series,and the highest and lowest values were observed in the mid-coniferous stage and shrub forest stage,respectively.Most importantly,the carbon stored in coarse woody debris in later successional forests was four times higher than in earlier successional forests.Conclusions:The stock and role of woody debris,particularly coarse woody debris,varied greatly with the forest successional stage and dominated the carbon cycle in the subalpine forest ecosystem.Thus,preserving coarse woody debris is a critical strategy for sustainable forest management.
基金support by project SUPERB H2020(Systemic solutions for upscaling of urgent ecosystem restoration for forest related biodiversity and ecosystem services)support by project P2013/MAE-2760(Autonomous Community of Madrid)+3 种基金support by project PID2019-107256RB-I00(Spanish Ministry of Science and Innovation)project FAGUS by the Comunidad de Madrid through the call Research Grants for Young Investigators from Universidad Polit ecnica de Madridsupport by projects 9OHUU0-10-3L226X(Autonomous Community of Madrid)RTI2018-094202-BC21 and RTI2018-094202-A-C22(Spanish Ministry of Science and Innovation)。
文摘There is an increasing interest in restoring degraded forests,which occupy half of the forest areas.Among the forms of restoration,passive restoration,which involves the elimination of degrading factors and the free evolution of natural dynamics by applying minimal or no management,is gaining attention.Natural dynamics is difficult to predict due to the influence of multiple interacting factors such as climatic and edaphic conditions,composition and abundance of species,and the successional character of these species.Here,we study the natural dynamics of a mixed forest located in central Spain,which maintained an open forest structure,due to intensive use,until grazing and cutting were banned in the 1960s.The most frequent woody species in this forest are Fagus sylvatica,Quercus petraea,Quercus pyrenaica,Ilex aquifolium,Sorbus aucuparia,Sorbus aria and Prunus avium,with contrasting shade and drought tolerance.These species are common in temperate European deciduous forest and are found here near their southern distribution limit,except for Q.pyrenaica.In order to analyze forest dynamics and composition,three inventories were carried out in 1994,2005 and 2015.Our results show that,despite the Mediterranean influence,the natural dynamics of this forest has been mainly determined by different levels of shade tolerance.After the abandonment of grazing and cutting,Q.pyrenaica expanded rapidly due to its lower shade tolerance,whereas after canopy closure and forest densification,shade-tolerant species gained ground,particularly F.sylvatica,despite its lower drought and late-frost tolerance.If the current dynamics continue,F.sylvatica will overtake the rest of the species,which will be relegated to sites with shallow soils and steep slopes.Simultaneously,all the multi-centennial beech trees,which are undergoing a rapid mortality and decline process,will disappear.
基金financial support within the research programs P1-0403 and J1-2457, funded by the Slovenian Research Agency。
文摘The main species composition drivers in temperate deciduous forests are environmental conditions, a stand?s age and the site history, e.g., the succession stage and past land use, as well as disturbance regime and current management. We compared plant species diversity and composition in late successional and ancient forests, cooccurring on the same small river island applying species accumulation curves and nonmetric multidimensional scaling, respectively. Given the island?s geomorphological characteristics, we expected these to be very similar before human intervention in the past. The forests experienced differing disturbance regimes in the past, while over the last 30 years, human intervention has been the same and reduced to a minimum. The ancient forest in this study had two major characteristics defining it as old, mature forest: continuity of presence for more than 200years and specific composition. The late successional forest experienced major disturbance in the 20th century and was allowed natural regeneration by bordering on the ancient forest, representing a potential species pool,and by decades of minimum human intervention. Our results showed that, even though there was no difference in species richness, we could still detect differences between the forests, particularly in the abundance and species composition of the understorey, among which geophytes had the most indicative importance. To make our results useful on a broader scale, we composed from the literature a species list of plants indicative for ancient forest and tested its application. These results are important for distinguishing between old and mature secondary stands and particularly for identifying old forest stands, which should be conserved and, in the case of fragmented landscapes, included in a network connecting forest fragments.
文摘Aims We investigated shifts in community-weighted mean traits(CWm)of 14 leaf functional traits along a secondary successional series in an evergreen broadleaf forest in subtropical southeast China.most of the investigated traits have been reported to affect litter decomposition in previous studies.We asked whether changes in CWms along secondary succession followed similar patterns for all investigated traits and whether the shifts in CWm indicated a change in resource use strategy along the successional gradient.using community decomposition rates(k-rates)estimated from annual lit-ter production and standing litter biomass,we asked whether the dynamics of litter decomposition were related to changes in leaf functional traits along the successional series.Methods twenty-seven plots were examined for shifts in leaf CWm traits as well as in k-rates along a series of secondary forest succession cov-ered in the framework of the bEF-China project.We investigated whether the changes in CWms followed similar patterns for all traits with ongoing succession.three alternative linear models were used to reveal the general patterns of shifts in CWm trait values.moreover,multiple regression analysis was applied to investigate whether there were causal relationships between the changes in leaf functional traits and the dynamics of litter decomposition along secondary succession.We furthermore assessed which traits had the highest impact on community litter decomposition.Important Findingsshifts in CWm values generally followed logarithmic patterns for all investigated traits,whereas community k-rates remained stable along the successional gradient.In summary,the shifts in CWm values indicate a change in community resource use strategy from high nutrient acquisition to nutrient retention with ongoing succession.stands with higher CWm values of traits related to nutrient acquisition had also higher CWm values of traits related to chemical resistance,whereas stands with higher CWm values of traits related to nutrient retention exhibited higher CWm values in leaf physical defense.moreover,high values in CWm values related to nutritional quality(such as high leaf phosphorus concentrations)were found to promote com-munity k-rates,whereas high values in physical or chemical defense traits(such as high contents in polyphenols or high leaf toughness)decreased litter decomposition rates.In consequence,litter decom-position,which was simultaneously affected by these characteristics,did not change significantly along succession.our findings show that leaf decomposition within the investigated communities is dependent on the interplay of several traits and is a result from interactions of traits that affect decomposition in opposing directions.
基金This research was made possible through the financial support of the Brazilian Agriculture Research Corporation(EMBRAPA)[03.13.07.007.00]We acknowledge financial support provided by CAPES and CNPq as a research fellowship for B.K.
文摘Aims Assessing the role of a dominant native bamboo species on tree species diversity and structure in the medium term.Methods Over a 7-year period,we studied the natural regeneration of two dominant forest types in Southern Brazil(Araucaria Forest or AF;Bamboo Forest or BF)after a bamboo(Merostachys skvortzovii Send.)die-off between 2004 and 2006.The study was carried out in the Embrapa Research Station in Cacador,Santa Catarina State,Brazil.Important Findings The die-off provided ideal conditions for the establishment of several species and it kickstarted forest succession dynamics,which in turn affected regeneration diversity.Tree species richness was relatively stable with a transitory increase between 2007 and 2014 in both AF and BF.However,species richness rose in BF because of a relative increase in abundance of some species(especially late and secondary species)while a plunge in some pioneer species drove an increase in diversity.Overall,we found that BF has a lower diversity of recruits and that density declined over time,while AF is more diverse,with a more stable density.In BF,the bamboo die-off created optimal conditions for initial regeneration development(mainly fast-growing pioneer trees),which quickly transited to higher size classes.Yet,after this initial stage of pioneer recruitment,the number of recruits dropped followed by a virtual absence of growth regardless of the species group as a result of a quick bamboo reestablishment.As bamboo recreated a dense understory it reduced species diversity to original levels,suggesting a self-maintaining cycle that halts forest succession.On the other hand,the bamboo die-off had little impact on AF where a slow recruitment process typical of old-growth forests was observed.The results indicate that the die-off event had a temporary effect on species diversity i.e.restricted to forests where bamboos are dominant in a similar process described in other southern South American forests.As the first study to observe the medium-term forest dynamics related to bamboo die-off,we can conclude that when being dominant,native bamboos can hinder forest regeneration,maintaining lower levels of diversity and arresting forest succession that lasts well beyond the short-term,post-die-off effects.Many forest fragments in the region are dominated by bamboos,thus their potential for conservation is at risk and requires appropriate management.
基金financial support of the German Research Foundation(DFG,Research Unit 816)for initializing the forest plots and the plot census as well as a first model parameterisationthe Helmholtz Alliance:Remote Sensing and Earth System Dynamics for financing the work on the further parameterisation of the model and analysis of the data
文摘Background: Tropical forests play an important role in the global carbon(C) cycle.However, tropical montane forests have been studied less than tropical lowland forests, and their role in carbon storage is not well understood.Montane forests are highly endangered due to logging, land-use and climate change.Our objective was to analyse how the carbon balance changes during forest succession.Methods: In this study, we used a method to estimate local carbon balances that combined forest inventory data with process-based forest models.We utilised such a forest model to study the carbon balance of a tropical montane forest in South Ecuador, comparing two topographical slope positions(ravines and lower slopes vs upper slopes and ridges).Results: The simulation results showed that the forest acts as a carbon sink with a maximum net ecosystem exchange(NEE) of 9.3 Mg C?(ha?yr)-1during its early successional stage(0–100 years).In the late successional stage, the simulated NEE fluctuated around zero and had a variation of 0.77 Mg C?(ha?yr)–1.The simulated variability of the NEE was within the range of the field data.We discovered several forest attributes(e.g., basal area or the relative amount of pioneer trees) that can serve as predictors for NEE for young forest stands(0–100 years) but not for those in the late successional stage(500–1,000 years).In case of young forest stands these correlations are high, especially between stand basal area and NEE.Conclusion: In this study, we used an Ecuadorian study site as an example of how to successfully link a forest model with forest inventory data, for estimating stem-diameter distributions, biomass and aboveground net primary productivity.To conclude, this study shows that process-based forest models can be used to investigate the carbon balance of tropical montane forests.With this model it is possible to find hidden relationships between forest attributes and forest carbon fluxes.These relationships promote a better understanding of the role of tropical montane forests in the context of global carbon cycle, which in future will become more relevant to a society under global change.
基金The study was supported by the National Natural Science Foundation of China(Grant No.30870399).
文摘In cold or alpine areas of northern China,birch forests and larch forests are the two primary forest types.These forests are also characteristic of a south branch of boreal forests in Asia.Some ecologists argue that larch forests can replace birch forests,but this still remains a question due to fragmentary or short observations.The ecotone between a larch forest patch and a birch forest patch is the arena in which the two species interplay and compete with each other,and studies of these areas are meaningful to understanding forest succession.In the alpine area of the Baihuashan Reserve,northern China,we sampled a larch-birch forest ecotone with eight plots in four transects and then analyzed population structures of larches and birches.The results show that the edges of the larch forest patch are composed of many larch saplings or young trees,but the edges of the birch forest patch are mainly composed of old birches.Across the ecotone,the larches,on average,are taller than the birches.These facts suggest that larch saplings can permeate into birch forest patches,probably by seed dispersal,germination,success-ful competition and growth,but birch saplings cannot permeate into larch forest patches.Therefore,on the ecotone,larch forest patches can steadily expand by unceasing permeation into birch forest patches,whereas birch forest patches progressively recede due to ultimate death of the old and poor recruitment of the young.Larch forest patches replace birch forest patches in a stepwise manner,causing succession from birch forests to larch forests.This study not only confirms that larch forests can naturally replace birch forests,but also introduces a simple and reliable method,employing spatial hints,to study forest succession.Additionally,the findings are of benefit to cultivation or development of larch forests in cold or alpine areas of the North Temperate Zone,which can be a huge carbon sink.
基金This study is funded by the Coordination for the Improvement of Higher Education Personnel(CAPES).
文摘As forests in neotropical regions,particularly in developing countries,are devastated,interventions to restore biodiversity and its ecological functions are needed.Rural producers have thus been encouraged to grow trees for wood production as an economic activity.The objective of this study was to quantify the increment of wood density of four forest species from different successional classes of a mixed system of restoration in a neotropical forest in Brazil.Tree discs were sampled at breast height and analyzed radially by X-ray densitometry to obtain apparent density and basic density.Three trees each of a species from the pioneer,early and late secondary successional stages and of the dominant species in the climax community.The radial profiles indicated increasing density from the pith to bark of trunks,except for some variations due to wood defects and growth.Average density was 0.576 g cm^(-3),0.655 g cm^(-3),0.706 g cm^(-3)and 0.775 g cm^(-3),respectively,for Peltophorum dubium,Schinus terebinthifolius,Cariniana estrellensis and Hymenaea courbaril.Radial profiles indicated higher amplitudes in the apparent densities for slow-growing species.X-ray densitometry generated parameters such as minimum,average and maximum densities,and radial density variations.These parameters are important for understanding the ecological functional role of successional classes of the Atlantic Forest from the Neotropical region.
基金supported by the grants from the Chinese National Natural Science Foundation(31160156)the Ministry of Science and Technology(2006BAD03A042012BAD22B01)
文摘Subalpine dark coniferous forests in the western Sichuan Province of China play an important role in the hydrological processes in the upper reaches of the Yangtze River. Second-growth forests, with different stand successional stages, have developed as a result of logging over the past 50 years. Forest cover and stand structure changed greatly with concomitant degradation of forest ecosystem functions. To understand how the stand structures of the second-growth forests change during the stand succession process, we analyzed stand structure characteristics and an old-growth state index of the bamboo and moss-forest types. We found that stand structure at the young successional stage featured one-third of the structure characteristics of the old-growth dark coniferous forests,while the structure of the medium-aged stage had reached half the structure of the old-growth state. The two forest types were similar in the rate of development at the young successional stage but differed at the medium-aged stage;the moss-forest type had more advanced development than the bamboo-forest type at the medium-aged successional stage.
基金funded by the Center for Forest Ecosystem Assessment(CFEA),USDA Forest Service,and Alabama A&M Universityadditional funding from the Alabama Ornithological Society and Birmingham Audubon Society
文摘Background: The early stage of forest succession following disturbance is characterized by a shift in songbird composition as well as increased avian richness due to increased herbaceous growth in the forest understory. However, regeneration of woody species eventually outcompetes the herbaceous understory, subsequently shifting vegetation communities and decreasing availability of vital foraging and nesting cover for disturbance-dependent birds, ultimately resulting in their displacement. These early stages following forest disturbance, which are declining throughout the eastern United States, are ephemeral in nature and birds depend on such disturbances for nesting and other purposes throughout their lives.Methods: We investigated the use of a two-stage shelterwood method to manage long-term persistence of seven early successional songbirds over a 13-year period in an upland hardwood forest within the southern end of the midCumberland Plateau in the eastern United States.Results: Canopy and midstory gaps created after initial harvest were quickly exploited by tree growth and canopy cover returned to these areas, accelerating the displacement of early-successional species. Woody stem densities increased substantially following stage two harvest as advanced tree regeneration combined with the re-opening of the overstory layer increased resource competition for early-successional plants in the understory. Carolina Wren(Thryothorus ludovicianus), Eastern Towhee(Pipilo erythrophthalmus), Indigo Bunting(Passerina cyanea), and Yellowbreasted Chat(Icteria virens) were characterized by immediate increases following initial harvest in 2001; while the American Goldfinch(Spinus tristis), Prairie Warbler(Setophaga discolor), and White-eyed Vireo(Vireo griseus) did not show an immediate response. Stage two harvest in 2011 rejuvenated vegetation which benefitted focal species, with six of seven species showing increases in densities between 2010 and 2012.Conclusion: The two-stage shelterwood method created conditions advantageous to early-successional birds by helping to re-establish understory vegetation through periodic disturbance to the canopy layer. This method provides evidence that early-successional species can be managed long-term(> 15 years) while using relatively small spatial disturbance through the two-stage shelterwood method.
基金supported by the Herrick Foundation,Kent University。
文摘Periodical cicadas(Magicicada spp.)are endemic to deciduous forests in the eastern United States.In successional forests,they must partition resources such as host trees to coexist.We measured tree size,emergence holes,oviposition scar bundles,and chorusing center abundances of Magicicada species on 12 common tree species in a deciduous forest to understand host-tree use.We predicted that the abundance of periodical cicadas and use of specific host-tree species would change depending on the Magicicada species and tree life stage.We considered the size of the tree(diameter at breast height)as a covariate to control for tree size and collected eggs for a greenhouse experiment to assess whether nymphs prefer to feed on Quercus rubra or Acer saccharum.More emergence holes were found below Quercus species than any other tree species.The abundance of periodical cicadas on host trees used for chorusing centers varied depending on the Magicicada species,but were most abundant on Quercus species.Oviposition scar bundles were also more frequent on Quercus.More nymphs were found on Quercus than Acer in the nymph preference study.Though periodical cicadas used Quercus hosts more than other tree species,their abundances on different host tree sizes and species differed significantly.Periodical cicada species may use specific host species and life stages as a way to partition resources and minimize competition among the Magicicada species during emergence years.
基金jointly supported by the China Postdoctoral Science Foundation(No.2020 M682951)the National Natural Science Foundation of China(No.NSFC41773088)the Key Research Program of the Chinese Academy of Sciences(No.QYZDJ-SSW-DQC003).
文摘Background:Old-growth forests are irreplaceable with respect to climate change mitigation and have considerable carbon(C)sink potential in soils.However,the relationship between the soil organic carbon(SOC)turnover rate and forest development is poorly understood,which hinders our ability to assess the C sequestration capacity of soil in old-growth forests.Methods:In this study,we evaluated the SOC turnover rate by calculating the isotopic enrichment factor β(defined as the slope of the regression between ^(13)C natural abundance and log-transformed C concentrations)along 0-30 cm soil profiles in three successional forests in subtropical China.A lower β(steeper slope)is associated with a higher turnover rate.The three forests were a 60-year-old P.massoniana forest(PF),a 100-year-old coniferous and broadleaved mixed forest(MF),and a 400-year-old monsoon evergreen broadleaved forest(BF).We also analyzed the soil physicochemical properties in these forests to examine the dynamics of SOC turnover during forest succession and the main regulators.Results:The β value for the upper 30-cm soils in the BF was significantly(p<0.05)higher than that in the PF,in addition to the SOC stock,although there were nonsignificant differences between the BF and MF.The β value was significantly(p<0.05)positively correlated with the soil recalcitrance index,total nitrogen,and available nitrogen contents but was significantly(p<0.01)negatively correlated with soil pH.Conclusions:Our results demonstrate that SOC has lower turnover rates in old-growth forests,accompanied by higher soil chemical recalcitrance,nitrogen status,and lower soil pH.This finding helps to elucidate the mechanism underlying C sequestration in old-growth forest soils,and emphasizes the important value of old-growth forests among global C sinks.
基金financially supported by Ministry of Science and Technology,China (Project No.2015FY210200–15)。
文摘Background: Schima genus of Theaceae is confined to subtropics and tropics of South, East and Southeast Asia.Thirteen species of Schima are distributed in subtropical China. Many of them appear as dominant canopy species in the subtropical forests. To date, Schima species richness distribution patterns of China have remained unknown.Meanwhile, there has been a longtime debate as to whether forests dominated by Schima species are early or late successional forests. We aim to clarify Schima species richness patterns and these species' roles in the forest succession and regeneration dynamics of the subtropical ecosystem in Yunnan Province, China.Method: We mapped Schima species richness distribution patterns in China. Based on 71 vegetation plots, we analyzed forest characteristics, population structure, and regeneration dynamics of Schima species in Yunnan.Results: Yunnan was found to harbor the greatest richness and the highest rarity-weighted richness of Schima species in the subtropical regions of China. We classified five primary and six secondary forest types containing Schima species as one of dominants. Yunnan had the high floristic diversity and varying stand structure of forests containing Schima species. The Schima species studied generally had a sporadic regeneration type and a long lifespan. Four species(Schima argentea, Schima villosa, Schima sinensis, Schima sericans) were shade-intolerant. But three species(Schima noronhae, Schima khasiana and Schima wallichii) were considered as bi-modal type species having shade-intolerant and shade-tolerant traits. Schima noronhae was seen to be a top dominant in late successional forests, while S. wallichii was found as a top-dominant in early or middle or late successional forests. S.khasiana, Schima villosa, Schima sinensis usually appeared as a top dominant in early or middle successional secondary forests, though they also presented as a second dominant in late-successional forests. Schima argentea and Schima sericans dominated only in the early or middle/seral successional forests. Schima species' regeneration establishment depended mainly on forest canopy gap formation through moderate human and natural disturbances.Conclusions: Yunnan has high species richness and rarity-weighted richness of Schima. Both moderate human and natural disturbances have provided regeneration niches for Schima species. Some of the Schima species studied as a second dominant(rare as the top-dominant) present in the late-successional forests. Some of them are more often as the top-dominant in early or middle successional forests, where as time goes by the dominance of Schima species would be replaced by their associated dominant taxa such as Castanopsis species.
文摘Background:Conceptual models of forest dynamics are powerful cognitive tools,which are indispensable for communicating ecological ideas and knowledge,and in developing strategic approaches and setting targets for forest conservation,restoration and sustainable management.Forest development through time is conventionally described as a directional,or "linear",and predictable sequence of stages from "bare ground" to old forest representing the "climax-state".However,this simple view is incompatible with the current knowledge and understanding of intrinsic variability of forest dynamics.Hypothesis:Overly simple conceptual models of forest dynamics easily become transformed into biased mental models of how forests naturally develop and what kind of structures they display.To be able to communicate the essential features and diversity of forest dynamics,comprehensive conceptual models are needed.For this end,Kuuluvainen(2009) suggested a relatively simple conceptual model of forest dynamics,which separates three major modes of forest dynamics,and incorporates state changes and transitions between the forest dynamics modes depending on changes in disturbance regime.Conclusions:Conceptual models of forest dynamics should be comprehensive enough to incorporate both longterm directional change and short-term cyclic forest dynamics,as well as transitions from one dynamics mode to another depending on changes in the driving disturbance regime type.Models that capture such essential features of forest dynamics are indispensable for educational purposes,in setting reference conditions and in developing methods in forest conservation,restoration and ecosystem management.
基金funded by CNPq(Brazilian National Council for Scientific and Technological Development)
文摘Background: In recent decades, native Araucaria forests in Brazil have become fragmented due to the conversion of forest to agricultural lands and commercial tree plantations. Consequently, the forest dynamics in this forest type have been poorly investigated, as most fragments are poorly structured in terms of tree size and diversity. Methods; We developed a distance-independent individual tree-growth model to simulate the forest dynamics in a native Araucaria forest located predominantly in southern Brazil. The data were derived from 25 contiguous plots (1 ha) established in a protected area left undisturbed for the past 70 years. The plots were measured at 3-year intervals from their establishment in 2002. All trees above a l O-cm diameter at breast height were tagged, identified as to species, and measured. Because this forest type comprises hundreds of tree species, we clustered them into six ecological groups: understory, subcanopy, upper canopy shade-tolerant, upper canopy light-demanding, pioneer, and emergent. The diameter increment, survival, and recruitment sub-models were fitted for each species group, and parameters were implemented in a simulation software to project the forest dynamics. The growth model was validated using independent data collected from another research area of the same forest type. To simulate the forest dynamics, we projected the species group and stand basal areas for 50 years under three different stand-density conditions: low, average, and high. Results: Emergent species tended to grow in basal area, irrespective of the forest density conditions. Conversely, shade-tolerant species tended to decline over the years. Under low-density conditions, the model showed a growth tendency for the stand basal area, while under average-density conditions, forest growth tended to stabilize within 30 years. Under high-density conditions, the model indicated a decline in the stand basal area from the onset of the simulation, suggesting that under these conditions, the forest has already reached its maximum-stock capacity. Conclusions: The model validation using independent data indicated close agreement between the observed and estimated values, suggesting the model is consistent in projecting species-group and stand growth. The methodology used in this study for developing the growth model should be tested in other species-rich forests.
文摘The Atlantic Forest is among the 35 hotspots on the planet, and yet few floristic or structural studies have been conducted on mature forest fragments of that biome in Brazil. In view of this knowledge gap and of the need to further comprehend the importance of conserving mature forests, we surveyed the arboreal component of three little-altered forest remnants from the S?o Paulo metropolitan region (SPMR), southeastern Brazil, and compared our data with the one from other phytosociological studies performed in the region. Mature forests showed a different floristic composition from one of young forests. Overall, the former has a higher number and percentage of threatened and endemic species than the latter, and also a higher exclusivity of occurrence of threatened species. In areas up to twice as smaller, mature forests have 1.5 to 4.3 times more endemic species to the Atlantic Forest and up to 9 times more species threatened with extinction than young forests. These facts, along with the scarcity of remnants of mature forests, led us to consider such forests as hotspots within the Atlantic Forest hotspot in the SPMR, as well as to categorize them as of high relevance for conservation.