Lipid concentration and composition in xylem sap of woody angiosperms from a tropical savanna and a seasonal rainforest

Lipids may play an important role in preventing gas embolisms by coating nanobubbles in xylem sap.Few studies on xylem sap lipids have been reported for temperate plants,and it remain unclear whether sap lipids have adaptational significance in tropical plants.In this study,we quantify the lipid composition of xylem sap for angiosperm species from a tropical savanna(seven species)and a seasonal rainforest(five species)using mass spectrometry.We found that all twelve species studied contained lipids in their xylem sap,including galactolipids,phospholipids and triacylglycerol,with a total lipid concentration ranging from 0.09 to 0.26 nmol/L.There was no difference in lipid concentration or composition between plants from the two sites,and the lipid concentration was negatively related to species’open vessel volume.Furthermore,savanna species showed little variation in lipid composition between the dry and the rainy season.These results support the hypothesis that xylem sap lipids are derived from the cytoplasm of individual conduit cells,remain trapped inside individual conduits,and undergo few changes in composition over consecutive seasons.A xylem sap lipidomic data set,which includes 12 tropical tree species from this study and 11 temperate tree species from literature,revealed no phylogenetic signals in lipid composition for these species.This study fills a knowledge gap in the lipid content of xylem sap in tropical trees and provides additional support for their common distribution in xylem sap of woody angiosperms.It appears that xylem sap lipids have no adaptive significance.

Differential roles of seed and sprout regeneration in forest diversity and productivity after disturbance

Natural regeneration after disturbances is a key phase of forest development,which determines the trajectory of successional changes in tree species composition and diversity.Regenerating trees can originate from either seeds or sprouts produced by disturbed trees with sprouting ability.Although both regeneration strategies often develop and co-occur after a disturbance,they tend to affect forest development differently due to significant functional differences.However,the origin of tree regeneration is rarely distinguished in post-disturbance forest surveys and ecological studies,and the differential roles of seed and sprout regeneration in forest productivity and diversity remain poorly understood.To address these research gaps,we explored the role of sprout and seed regeneration in the formation of woody species diversity and above-ground biomass(AGB)productivity in early-stage forest development.Data were collected in two experimental forest stands in the Czech Republic,where trees were cut with varying intensities with the density of residual(uncut)trees ranging from 0 to 275 trees per hectare.All trees were mapped and their sizes were measured before cutting and then,either as a stump with sprouts or a residual tree,remeasured 11 years later.In addition,all tree saplings were mapped and measured 11 years after logging,and their origin(sprout or seed)was identified.To assess abundances and productivity,we estimated AGB of all2,685 sprouting stumps of 19 woody species and 504 generative(i.e.,seed origin)individuals of 16 woody species,using allometric equations.Mixed-effects models were used to analyze the effects of each regeneration strategy on woody species diversity and the total AGB under varying densities of residual trees.Nonmetric multidimensional scaling was used to evaluate the effect of regeneration strategies on species composition.AGB and diversity of sprouts were significantly higher than those of seed regeneration.Sprouts formed on average97.1%of the total regeneration AGB in H ady and 98.6%in Sobe s ice.The average species richness of sprouts was4.7 in H ady and 2.2 in Sob e sice,while the species richness of seed regeneration averaged 2.1 and 1.1 in H ady and Sob e sice,respectively.Increasing density of residual trees reduced AGB and diversity of both sprouts and seed regeneration,but seed regeneration was affected to a greater extent.Residual trees had an especially strong inhibitory effect on the establishment of seed regeneration.Consequently,seed-originated saplings were nearly absent in plots with high residual tree density,and abundant sprouts accounted for most of the AGB and diversity.However,unlike sprouts whose species composition resembled that of the original stand,seed regeneration brought in new species,enriching the stand?s overall species pool and beta diversity.Our results demonstrated differential roles of sprout and seed regeneration in the early stage of forest succession.Sprout regeneration was the main source of woody AGB productivity as well as species diversity,and its importance increased with the increasing density of standing mature trees.The results indicate the crucial yet previously underestimated role of sprout regeneration in post-disturbance forest dynamics.They suggest that the presence of residual mature trees,whether retained after partial cutting or undisturbed,can substantially suppress seed regeneration while the role of sprout regeneration in early succession becomes more distinctly evident.

Aboveground biomass stocks of species-rich natural forests in southern China are influenced by stand structural attributes,species richness and precipitation

Forests,the largest terrestrial carbon sinks,play an important role in carbon sequestration and climate change mitigation.Although forest attributes and environmental factors have been shown to impact aboveground biomass,their influence on biomass stocks in species-rich forests in southern China,a biodiversity hotspot,has rarely been investigated.In this study,we characterized the effects of environmental factors,forest structure,and species diversity on aboveground biomass stocks of 30 plots(1 ha each) in natural forests located within seven nature reserves distributed across subtropical and marginal tropical zones in Guangxi,China.Our results indicate that forest aboveground biomass stocks in this region are lower than those in mature tropical and subtropical forests in other regions.Furthermore,we found that aboveground biomass was positively correlated with stand age,mean annual precipitation,elevation,structural attributes and species richness,although not with species evenness.When we compared stands with the same basal area,we found that aboveground biomass stock was higher in communities with a higher coefficient of variation of diameter at breast height.These findings highlight the importance of maintaining forest structural diversity and species richness to promote aboveground biomass accumulation and reveal the potential impacts of precipitation changes resulting from climate warming on the ecosystem services of subtropical and northern tropical forests in China.Notably,many natural forests in southern China are not fully stocked.Therefore,their continued growth will increase their carbon storage over time.

Aging Mongolian pine plantations face high risks of drought-induced growth decline:evidence from both individual tree and forest stand measurements

Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.

Multi-year throughfall reduction enhanced the growth and non-structural carbohydrate storage of roots at the expenses of above-ground growth in a warm-temperate natural oak forest

The more frequent occurrence and severer drought events resulting from climate change are increasingly affecting the physiological performance of trees and ecosystem carbon sequestration in many regions of the world.However,our understanding of the mechanisms underlying the responses and adaption of forest trees to prolonged and multi-year drought is still limited.To address this problem,we conducted a long-term manipulative throughfall reduction(TFR,reduction of natural throughfall by 50%–70%during growing seasons)experiment in a natural oriental white oak(Quercus aliena var.acuteserrata Maxim.)forest under warm-temperate climate.After seven years of continuous TFR treatment,the aboveground growth in Q.aliena var.acuteserrata started to decline.Compared with the control plots,trees in the TFR treatment significantly reduced growth increments of stems(14.2%)and leaf area index(6.8%).The rate of net photosynthesis appeared to be more susceptible to changes in soil water in trees subjected to the TFR than in the control.The TFR-treated trees allocated significantly more photosynthates to belowground,leading to enhanced growth and nonstructural carbohydrates(NSC)storage in roots.The 7-year continuous TFR treatment increased the biomass,the production and the NSC concentration in the fine roots by 53.6%,153.6%and 9.6%,respectively.There were clear trade-offs between the aboveground growth and the fine root biomass and NSC storage in Q.aliena var.acuteserrata trees in response to the multi-year TFR treatment.A negative correlation between the fine root NSC concentration and soil water suggested a strategy of preferential C storage over growth when soil water became deficient;the stored NSC during water limitation would then help promote root growth when drought stress is released.Our findings demonstrate the warm-temperate oak forest adopted a more conservative NSC use strategy in response to long-term drought stress,with enhanced root growth and NSC storage at the expenses of above-ground growth to mitigate climate changeinduced drought.

Nest-site selection and breeding ecology of Streaked Wren-Babbler(Napothera brevicaudata)in a tropical limestone forest of southern China

Background: The breeding information of most birds in Asian tropical areas,especially in limestone forests,is still poorly known.The Streaked Wren-Babbler(Napothera brevicaudata) is an uncommon tropical limestone bird with a small range.We studied its nest-site selection and breeding ecology,in order to understand the adaptations of birds to the conditions of tropical limestone forest in southern China.Methods: We used methods of systematical searching and parent-following to locate the nests of the Streaked Wren-Babbler.We measured characteristics of nest sites and rock cavities.Data loggers and video cameras were used to monitor the breeding behavior.Results: All the observed nests of the Streaked Wren-Babbler were placed in natural shallow cavities or deep holes in large boulders or limestone cliffs.The great majority(96.6%) of Streaked Wren-Babbler nests had three eggs with an average fresh weight of 3.46-± 0.43 g(n = 36,range 2.52-4.20 g).Most(80.4%) females laid their first eggs between March and April(n = 46).The average incubation and nestling period of the Streaked Wren-Babbler was 10.2 range 9-11 days),respectively.Most(87.9%) nests h± 0.4 days(n = 5,range 1011 days) and 10.5 ± 0.8 days(n = 6,ad at least one nestling fledge between 2011 and 2013(n = 33).Conclusions: Our study suggests that several features of the breeding ecology of the Streaked Wren-Babbler,including building nests in rocky cavities,commencing breeding earlier than most species,and reducing foraging times during the incubation period,are well-adapted to the unique habitat of tropical limestone forest.

The amelioration of degraded larch(Larix olgensis)soil depends on the proportion of Aralia elata litter in larch-A.elata agroforestry systems

Research has indicated that introducing Aralia elata into larch plantations forms an agroforestry system which could provide economic benefi ts for local farmers and improve degraded soils.However,the impact of litter mixtures on soil chemical and microbial properties in this agroforestry system are unclear,which limits effi cient management of the agroforestry system.A 365-d incubation experiment examined the eff ect of litter mixtures of diff erent proportions of larch(L)and A.elata(A)on soil chemical and microbial properties.The results show that levels of mineral N,available P,microbial biomass carbon and nitrogen,cumulative C mineralization,and activities of hydrolases and oxidases increased with an increase of A.elata in the litter mixtures.Concentration of total soil carbon,nitrogen,and phosphorous did not change(except for total nitrogen).Compared with larch litter alone,levels of mineral N,available P,microbial biomass carbon and nitrogen,cumulative C mineralization,and the activities of hydrolases and oxidases increased by 7.6–433.5%.Most chemical and microbial properties were positively correlated with mixed litter proportions and the initial levels of N,P,K,Ca,Mg,Mn,Zn and Cu in the litter,while negatively correlated with the initial concentrations of C,Fe and lignin,C/N and lignin/N ratios.The results indicate that A.elata litter can improve degraded larch soil and the degree depends on the proportion of A.elata litter in the litter mixtures.

Correction to:The amelioration of degraded larch(Larix olgensis)soil depends on the proportion of Aralia elata litter in larch-A.elata agroforestry systems

Correction to:J.For.Res.https://doi.org/10.1007/s11676-022-01526-w The article“The amelioration of degraded larch(Larix olgensis)soil depends on the proportion of Aralia elata litter in larch-A.elata agroforestry systems”,written by Pingzhen Gao·Jiaojun Zhu·Qiaoling Yan·Kai Yang and Jinxin Zhang was originally published Online First without Open Access.

Relationship between species diversity and tree size in natural forests around the Tropic of Cancer

Although numerous hypotheses have been proposed to explain the patterns of species diversity of forests at local and landscape levels,it is still difficult to predict the alpha diversity of species,especially in tropical and subtropical natural forests where trees of different sizes and shapes are highly mixed.Size might characterize species diversity,and the possible correlation between these variables may contribute to the development of easy-to-use growth indicators to predict diversity and to understand the status of trees within a stand.In this study,diameter classes were divided using the equal diameter class(EDC)and minimum measured diameter(MMD)methods,and five species diversity indices were calculated for each diameter class of 14 permanent plots in five national nature reserves surrounding the Tropic of Cancer(23.5°),southwest China.The results show that species richness,abundance,and spatial diversity indices decreased in a typical inverted J-shape pattern with increasing diameter class and MMD,and could be easily modeled by a negative exponential function.The ShannonWiener index showed a linear decrease while Pielou’s evenness index displayed a linear increase,with a small degree of instability.The results suggest that species diversity in subtropical forests is closely related to tree size,and the relationship is possibly independent of habitat.Measuring DBH of some trees in a stand could be informative regarding species diversity and contribute to the investigation and assessment of biodiversity.

Divergent responses of Picea crassifolia Kom.in different forest patches to climate change in the northeastern Tibetan Plateau

Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions,which are becoming warmer and wetter.Due to natural factors such as climate and terrain,some tree species may form different forest patches at the edges of their distribution areas.However,how forest patches of various sizes respond to climate change is unclear.In this study,we collected 203 tree cores from six different sizes of forest patches at the edge of the distribution area of Picea crassifolia Kom.in the northeast Tibetan Plateau.And we used the dendrochronology method to study the response of tree growth and resilience in different forest patches to climate change from 1961 to 2020.We simultaneously measured the contents of nonstructural carbohydrates(NSC),total nitrogen and total phosphorus of tree needles.Our results showed that the growth of trees in small-and medium-size forest patches(0.8–18.6 ha)has increased significantly.The early growing season(May–July)minimum temperature was the most important climate factor driving the growth of small-and medium-sized patch trees.The early growing season maximum temperature was the most important climate factor that inhibited the growth of trees in the largest patches(362.8 ha).The growth of individual trees in medium forest patches was better and the correlation with annual minimum temperature,maximum temperature,precipitation,actual evapotranspiration,and palmer drought severity index was stronger.The higher NSC content,stronger photosynthesis,and higher nitrogen utilization efficiency in leaves might be one of the reasons for the better growth of trees in moderate forest patches.In extreme drought years,as the forest patch area increased,the overall trend of tree growth resistance showed a unimodal pattern,with the highest at a forest patch area of 7.1 ha,while the overall trend of tree growth recovery was opposite.Therefore,we should strengthen the management of trees in large forest patches to cope with climate change.

Soil Seed Bank Characteristics of the Mbe and Nguela Shrub Savannas, and Implications for the Reforestation, Republic of Congo

The soil seed bank is an important source of restoration and resilience of disturbed ecosystems. This study evaluates the regeneration potential through the soil seed bank of the shrub savannas of Nguela and Mbe in order to predict the eventual dynamics. Three plots of 0.25 ha subdivided into four sub-plots of 0.015 ha have been installed in each savannah. In total, 48 samples of each savannah, i.e. 96 samples of both savannas, have been taken from the soil layers, 0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm. Species diversity and abundance of the soil seed bank have been assessed after germination. The results reveal 167 seedlings belonging to 23 species in the Mbe savannah and 144 seedlings belonging to 14 species in the Nguela savannah. The total densities of the germinated seeds were respectively 463.63 seeds/m2 and 400 seeds/m2. Nevertheless, the 20 cm deep layers have illustrated themselves compared to the superficial layers with densities of 16.29 seeds/m2 and 21.66 seeds/m2, respectively, in the savannas of Mbe and Nguela. Herbaceous species largely dominated, with percentages of 91% and 100%, respectively, in the savannas of Mbe and Nguela. Alone, the Trema orientalis (L.) Blume species has been identified as woody species in the Mbe savannah. The greatest specific richness has been obtained in the first five centimeters of soil, with 21.73% and 28.57% of exclusive species, respectively, in the savannas of Mbe and Nguela. The results reveal that restoration through the soil seed bank would be limited to a single woody species found (T. orientalis). Consequently, the study suggests silvicultural interventions based on planting or enrichment techniques for sustainably managed savannas exposed to anthropogenic disturbances.

Soil Seed Bank of the Marantaceae Forests of Ouesso Forest Industry (IFO), Republic of Congo

The soil seed bank is a key indicator of natural regeneration and/or forests resilience after disturbances. This study evaluates the soil seed bank characteristics in two Marantaceae forests plots of Ouesso Forest Industry (IFO) in north of the Republic of Congo. In each plot, 12 samples were taken per soil layers (0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm deep). Diversity and abundance seed were estimated after germination of soil samples. The results revealed 101 seedlings belonging to 17 species for plot 1 and 129 seedlings belonging to 15 species for plot 2. The average densities of germinated seeds were respectively 281 seedling/m2 and 358 seedling/m2. There were no significant differences (p > 0.05) between the mean densities of the two plots. Herbaceous species dominated with percentages of 71% and 73%, respectively in plot 1 and plot 2. Both plots showed potential of regeneration from the soil seed bank. However, this potential seems higher in plot 2. Pioneer taxa were more abundant in the soil seed bank of plot 1 (4 woody pioneer species) than in plot 2 (1 woody pioneer species). The highest species richness was obtained in the first two soil layers (0 - 5 cm and 5 - 10 cm depth) while 25% of species were exclusively found in the deepest layer (15 - 20 cm) in plot 2. The study suggests silvicultural interventions based on planting or enrichment techniques for contribute to sustainable management of Marantaceae forests that could prevent the growth and development of seedlings.

Effects of thinning and understory removal on water use efficiency of Pinus massoniana:evidence from photosynthetic capacity and stable carbon isotope analyses

Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management practices.In this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of China.Photosynthetic capacity and needle stable carbon isotope composition(δ^(13)C)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were insignificant.However,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water content.Understory removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability.In general,thinning may be an appropriate management measure to promote P.massoniana WUE to cope with seasonal droughts under future extreme climates.

Regeneration Potential of Woody Species at the Side of Secondary Roads Post-Logging of Loundoungou-Toukoulaka Forest Management Unit, Republic of the Congo

Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population.

Leaf habit differentiation explains trait tradeoffs across savanna woody plants

Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we tested a hypothesis that the differentiation across deciduous, semi-deciduous and evergreen woody species contributes to physiological trait tradeoffs in a dry-hot valley savanna. We investigated 11 photosynthetic, morphological and hydraulic traits of 24 species including 8 deciduous, 10 semi-deciduous and 6 evergreen species. Deciduous species were grouped in the fast and avoidance side associated with high values of maximum photosynthetic rates,stomatal conductance and leaf size, while evergreen species were grouped in the slow and tolerance side associated with high photosynthetic water use efficiency, leaf mass per area, sapwood density, Huber value, leaf water potential at turgor loss point and water potential causing 50% loss of stem hydraulic conductance. Semideciduous species generally had intermediate trait values and represented different physiological characteristics when compared to deciduous and evergreen species. The physiological trait tradeoffs showed a close linkage to the differentiation of these three leaf habits. Our findings clearly reveal trait tradeoffs related to fast–slow and avoidance–tolerance strategies among diverse savanna plants, suggesting a syndrome in multiple ecophysiology strategies across different leaf habits.

Litter quality and decomposer complexity co-drive effect of drought on decomposition

Litter decomposition is key to ecosystem carbon(C)and nutrient cycling,but this process is anticipated to weaken due to projected more extensive and prolonged drought.Yet how litter quality and decomposer community complexity regulate decomposition in response to drought is less understood.Here,in a five-year manipulative drought experiment in a Masson pine forest,leaf litter from four subtropical tree species(Quercus griffthii Hook.f.&Thomson ex Miq.,Acacia mangium Willd.,Pinus massoniana Lamb.,Castanopsis hystrix Miq.)representing different qualities was decomposed for 350 d in litterbags of three different mesh sizes(i.e.,0.05,1,and 5 mm),respectively,under natural conditions and a 50%throughfall rain exclusion treatment.Litterbags of increasing mesh sizes discriminate decomposer communities(i.e.,microorganisms,microorganisms and mesofauna,microorganisms and meso-and macrofauna)that access the litter and represent an increasing complexity.The amount of litter C and nitrogen(N)loss,and changes in their ratio(C/N_(loss)),as well as small and medium-sized decomposers including microorganisms,nematodes,and arthropods,were investigated.We found that drought did not affect C and N loss but decreased C/N_(loss)(i.e.,decomposer N use efficiency)of leaf litter irrespective of litter quality and decomposer complexity.However,changes in the C/N_(loss)and the drought effect on C loss were both dependent on litter quality,while drought and decomposer complexity interactively affected litter C and N loss.Increasing decomposer community complexity enhanced litter decomposition and allowing additional access of meso-and macro-fauna to litterbags mitigated the negative drought effect on the microbial-driven decomposition.Furthermore,both the increased diversity and altered trophic structure of nematode due to drought contributed to the mitigation effects via cascading interactions.Our results show that litter quality and soil decomposer community complexity co-drive the effect of drought on litter decomposition.This experimental finding provides a new insight into the mechanisms controlling forest floor C and nutrient cycling under future global change scenarios.

Ecology,growth and management of black locust(Robinia pseudoacacia L.),a non-native species integrated into European forests

Black locust(Robinia pseudoacacia L.),a species native to the eastern North America,was introduced to Europe probably in 1601 and currently extends over2.3×10~6 ha.It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp.as the second most planted broadleaved tree species worldwide after Eucalyptus spp.This wide-spreading planting is because black locust is an important multipurpose species,producing wood,fodder,and a source of honey as well as bio-oil and biomass.It is also important for carbon sequestration,soil stabilization and re-vegetation of landfills,mining areas and wastelands,in biotherapy and landscaping.In Europe,black locust is drought tolerant so grows in areas with annual precipitation as low as 500-550 mm.It tolerates dry,nutrient poor soils but grows best on deep,nutrient-rich,well-drained soils.It is a fast-growing tree and the height,diameter and volume growth peak before the age of 20.It mostly regenerates vegetatively by root suckers under a simple coppice system,which is considered the most cost-effective management system.It also regenerates,but less frequently,by stool sprouts.Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots,and cleaning-respacing to remove low-quality stems,reduce the number of shoots per stool,and adjust spacing between root suckers.In addition,early,moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees.The species is regarded as invasive in several European countries and its range here is expected to expand under predicted climate changes.

Carbon storage in evergreen broad-leaf forests in mid-subtropical region of China at four succession stages

To better understand the effect of forest succession on carbon sequestration, we investigated carbon stock and allocation of evergreen broadleaf forest, a major zonal forest in subtropical China. We sought to quantify the carbon sequestration potential. We sampled four forest types, shrub （SR）, pine （Pinus massoniana） forest （PF）, pin~ and broadleaf mixed forest （Mr） and evergreen broadleaf forest （BF）. A regression equation was constructed using tree height and diameter at breast height （DBH） and elements of total tree biomass. The equation was subse- quently utilized to estimate tree carbon storage. The carbon storage of understory, litter, and soil was also estimated.

Microbial biomass in subtropical forest soils： effect of conversion of natural secondary broad-leaved forest to Cunninghamia lanceolata plantation

到 Cunninghamialanceolata 种植园的自然第二等的阔叶的森林的变换是在副热带的中国的一个普通管理惯例。在这研究，我们比较了土壤物理化学的性质，在一天赋的微生物引起的生物资源第二等的 broad-leavedforest 和二 C。在土壤上估计森林变换的效果的 lanceolata 种植园地点在林地生态学的 Huitong 试验性的车站的微生物引起的生物资源，中国科学院。器官的碳，总氮， NH_4^+-N 和微生物引起的生物资源碳和氮多是的土壤的集中在 C 下面降低。lanceolata 种植园作为与自然离开 secondarybroad 的森林相比。在 C 的第一和第二旋转玷污微生物引起的生物资源 C。lanceolataplantations 仅仅是 53% ，那中的 46% 个分别地在自然第二等的阔叶的森林，和微生物引起的生物资源 N 里是 97% 和 79% 。到器官的 Cwas 也在种植园地点降低的土壤的微生物引起的生物资源 C 的贡献。然而，到总氮和 NH_4^+-N 的微生物引起的 N 的贡献在 C 是更大的。lanceolata 种植园地点。因此，到 C 的自然第二等的阔叶的森林的变换。lanceolata 种植园并且 C 的连续的种。lanceolataled 到在土壤的衰落微生物引起的生物资源和在副热带的中国的森林土的降级。

Future impacts of climate change on forest fire danger in northeastern China

Climate warming has a rapid and far-reaching impact on forest fire management in the boreal forests of China. Regional climate model outputs and the Canadian Forest Fire Weather Index （FWI） Sys- tem were used to analyze changes to fire danger and the fire season for future periods under IPCC Special Report on Emission Scenarios （SRES） A2 and B2, and the data will guide future fire management planning. We used regional climate in China （1961 1990） as our validation data, and the period （1991–2100） was modeled under SRES A2 and B2 through the weather simulated by the regional climate model system （PRECIS）. Meteorological data and fire danger were interpolated to 1 km 2 by using ANUSPLIN software. The average FWI value for future spring fire sea- sons under Scenarios A2 and B2 shows an increase over most of the region. Compared with the baseline, FWI averages of spring fire season will increase by 0.40, 0.26 and 1.32 under Scenario A2, and increase by 0.60, 1.54 and 2.56 under Scenario B2 in 2020s, 2050s and 2080s, respectively. FWI averages of autumn fire season also show an increase over most of the region. FWI values increase more for Scenario B2 than for Scenario A2 in the same periods, particularly during the 2050s and 2080s. Average future FWI values will increase under both scenarios for autumn fire season. The potential burned areas are expected to increase by 10% and 18% in spring for 2080s under Scenario A2 and B2, respectively. Fire season will be prolonged by 21 and 26 days under ScenariosA2 and B2 in 2080s respectively.