Tree species composition and diversity in montane forests of Garhwal Himalaya in relation to environmental and soil properties

The montane forests of Garhwal Himalaya were investigated for tree species composition and diversity in relation to environmental and edaphic variables.A stratified random sampling approach was adopted to collect the field data from each forest.A total of 39 tree species belonging to 31 genera and 23 families were recorded from the sampling area(6 forest stands ×10 plots in each).Lauraceae with 5 species was the largest family while Quercus(4 species) emerged as the largest genus.Species-area curve(asymptote) predicted more species than the observed number of species.Cluster analysis has shown that the two Abies pindrow dominant forest stands had the highest similarity in tree species composition.The tree stem density ranged from 540-1170 ha-1,basal area 23.01-55.94 m^2 ha-1,ShannonWiener diversity index 1.69-2.49,evenness index0.42-0.74,beta diversity 0.40-0.82 and similarity index 0.17-0.54 in the six studied forests.Two-way indicator species analysis(TWINSPAN) identified four distinct tree communities in the study area with Daphniphyllum himalayense,Abies pindrow,Quercus oblongata,and Pinus roxburghii as indicator species of corresponding communities.Canonical correspondence analysis(CCA) ascertained the TWINSPAN results and revealed the relation of tree species with environmental and edaphic variables.The phytosociological attributes of tree species varied from one forest stand to another;however,the tree species richness,density,and diversity peaked at intermediate elevation on the north aspect.Findings reveal that tree composition and diversity in the montane forests of Garhwal Himalaya are influenced by both environmental(elevation and slope aspect)and soil variables(texture,water holding capacity,moisture content,available N,exchangeable P,and pH).This study will help in understanding the forest distribution across the western Himalaya,guiding the conservationists and policymakers in carrying out conservation-related management activities,designing the long-term monitoring studies and assessing the effects of ongoing and future climate change and disturbances.

The carbon fluxes in different successional stages:modelling the dynamics of tropical montane forests in South Ecuador

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.

Conversion of Andean montane forest to exotic forest plantation modifies soil physicochemical properties in the buffer zone of Ecuador's Podocarpus National Park

Background:Andean montane forests(AMF)are biodiversity hotspots that provide fundamental hydrological services as well as carbon storage and sequestration.In recent decades,southern Ecuador AMFs have been seriously threatened by increased logging and conversion to forest plantations with exotic species.In this context,our main objective was to evaluate the effects of AMF conversion to forest plantations on soil physicochemical properties in the buffer zone(Bz)of the Podocarpus National Park(PNP),in southern Ecuador.For this purpose,random samples were taken at a depth of 0-10 cm in four plots in each contrast zone and analyzed for bulk density,porosity,textural class,leaf litter depth,soil pH,as well as the contents of organic matter(SOM),soil organic carbon(SOC),total nitrogen,and available phosphorus and potassium.Results:The results indicate that the conversion of AMFs produces an increase in bulk density and a decrease in SOM,SOC,and total nitrogen contents,thus modifying soil properties,which could result in a decrease in water regulation capacity and produce an increased risk of soil erosion.This accelerates degradation processes,as well as threatens shortages of the drinking water supply.Conclusions:This study can help decision-makers to implement soil management plans in the Bz of the PNP,based on the implementation of new regulations,where the conservation of AMF is promoted.In addition,it is recommended to apply environmental restoration strategies in the anthropized areas of the AMF,as well as in the areas with exotic eucalyptus and pine plantations.

Evolutionary fingerprint, phylogenetic and forest structure of tropical montane Atlantic cloud forests along an elevation gradient

Environmental conditions can change markedly over geographical distances along elevation gradients,making them natural laboratories to study the processes that structure communities.This work aimed to assess the influences of elevation on Tropical Montane Cloud Forest plant communities in the Brazilian Atlantic Forest,a historically neglected ecoregion.We evaluated the phylogenetic structure,forest structure(tree basal area and tree density)and species richness along an elevation gradient,as well as the evolutionary fingerprints of elevation-success on phylogenetic lineages from the tree communities.To do so,we assessed nine communities along an elevation gradient from 1210 to 2310 m a.s.l.without large elevation gaps.The relationships between elevation and phylogenetic structure,forest structure and species richness were investigated through Linear Models.The occurrence of evolutionary fingerprint on phylogenetic lineages was investigated by quantifying the extent of phylogenetic signal of elevation-success using a genus-level molecular phylogeny.Our results showed decreased species richness at higher elevations and independence between forest structure,phylogenetic structure and elevation.We also verified that there is a phylogenetic signal associated with elevation-success by lineages.We concluded that the elevation is associated with species richness and the occurrence of phylogenetic lineages in the tree communities evaluated in Mantiqueira Range.On the other hand,elevation is not associated with forest structure or phylogenetic structure.Furthermore,closely related taxa tend to have their higher ecological success in similar elevations.Finally,we highlight the fragility of the tropical montane cloud forests in the Mantiqueira Range in face of environmental changes(i.e.global warming)due to the occurrence of exclusive phylogenetic lineages evolutionarily adapted to environmental conditions(i.e.minimum temperature)associated with each elevation range.

Structure and regeneration status of Komto Afromontane moist forest, East Wollega Zone, west Ethiopia

We conducted a study in Komto Forest in East WoUega Zone, Oromia National Regional State, West Ethiopia for determining vegetation structure and regeneration status in this forest. We systematically sampled 53 quadrats （20 m ×20 m） along line transects radiating from the peak of Komto Mountain in eight directions. Vegetation parameters such as DBH, height, seedling and sapling density of woody species, and location and altitude of each quadrat were recorded. In total, 103 woody plant species of 87 genera and 45 families were identified. Analysis of selected tree species revealed different population structures. Generally, the forest was dominated by small trees and shrubs characteristic of secondary regeneration. Observations on the regeneration of the forest indicated that there are woody species that require urgent conservation measures. Based on the results of this study, we recommend detailed ecological studies of various environmental factors such as soil type and properties, and ethnobotanical studies to explore indigenous knowledge on uses of plants.

Mercury accumulation and dynamics in montane forests along an elevation gradient in Southwest China

Understanding atmospheric mercury(Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon(C), and nitrogen(N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C(from 237.0 ± 171.4 to 56.8 ± 27.7 μg/kg) and Hg/N(from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg ° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest(244.9 ± 55.7 μg/kg) and the lowest value in the alpine forest(151.9 ±44.5 μg/kg). Further analysis suggests that soil Hg is positively correlated to C( r^(2) = 0.66) and N( r^(2) = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.

Combined community ecology and floristics,a synthetic study on the upper montane evergreen broad-leaved forests in Yunnan,southwestern China

The upper montane evergreen broad-leaved forest in Yunnan occurs mainly in the zone of persistent cloud and has a discontinuous,island-like,distribution.It is diverse,rich in endemic species,and likely to be sensitive to climate change.Six 1-ha sampling plots were established across the main distribution area of the upper montane evergreen broad-leaved forest in Yunnan.All trees with d.b.h.>1 cm in each plot were identified.Patterns of seed plant distributions were quantified at the specific,generic and family levels.The forests are dominated by the families Fagaceae,Lauraceae,Theaceae and Magnoliaceae,but are very diverse with only a few species shared between sites.Floristic similarities at the family and generic level were high,but they were low at the specific level,with species complementarity between plots.Diversity varied greatly among sites,with greater species richness and more rare species in western Yunnan than central Yunnan.The flora is dominated by tropical biogeographical elements,mainly the pantropic and the tropical Asian distributions at the family and genus levels.In contrast,at the species level,the flora is dominated by the southwest or the southeast China distributions,including Yunnan endemics.This suggests that the flora of the upper montane forest in Yunnan could have a tropical floristic origin,and has adapted to cooler temperatures with the uplift of the Himalayas.Due to great sensitivity to climate,high endemism and species complementarity,as well as the discontinuous,island-like,distribution patterns of the upper montane forest in Yunnan,the regional conservation of the forest is especially needed.

Plant diversity and phenological pattern in the montane wet temperate forests of the southern Western Ghats,India

Plants diversity and phenological pattern of the trees were monitored in a montane wet temperate forest （shola） in the Kukkal Forest, Palni hills of the southern Western Ghats, India. Twelve random plots were selected for sampling the vegetation. For phenological studies, twenty-three fleshy fruit trees were identified in the study area and 10 individuals of each species were selected to record the phenological events fortnightly between April 2002 and April 2004. The phenological events were divided into vegetative and reproductive phases. A total of 2279 individuals were inventoried which belong to 83 species, 68 genera and 40 families. About 30% of the species were endemic to the Western Ghats. The most dominant species （〉 1 cm dbh） was Psychotria nilgiriensis var. astephana （Rubiaceae）, which accounted for 12% of the total sampled individuals. Lauraceae was the dominant family accounting for 20% of the individuals. Fruiting peak occurred in July 2003 and least in June 2002. During the peak period, fruits of 85 individuals of six species were observed. Syzygium tamilnadensis, Ilex wightiana and Beilschmiedia wightii fruited only once during the two years of study. The number of fruiting species showed no correlation with rainfall （r = 0.26, p = 0.2）, while a correlation was found with fruit abundance （r = 0.40, p 〈 0.05）. The results indicate that the montane wet temperate forest is unique in their diversity and a conspicuous display in phenology.

Can small-scale altitudinal gradients predict spatial and temporal patterns in tropical forests?

In tropical montane forests,compositional and structural changes are commonly driven by broad-scale altitudinal variation.Here,given the lack of knowledge on small-scale vegetation changes and temporal dynamics,we address the effects of small-scale variations in soil and altitude on tree community structure,temporal dynamics and phylogenetic diversity in a semi-deciduous tropical forest of the Atlantic Forest Domain,southeastern Brazil.In 2010 and 2015 we sampled thirty plots of 400 m^(2),set up along an altitudinal gradient between 1000 and 1500 m a.s.I..In each plot,we collected soil samples for chemical and textural analyses.We fitted linear models to test the effects of altitude and soil on community dynamics and phylogenetic parameters.Altitude and soil explained the spatial variation in number of individuals and phylogenetic diversity metrics.From lower to higher altitudes,we found decreasing fertility,increasing tree density and decreasing phylogenetic diversity.Altitude significantly influenced the increases in total biomass(from 240.9 to 255.4 t ha^(-1))and individual biomass(from 0.15 to 0.17 t)recorded in the interval.And while community temporal dynamics had rates of 1.96%for mortality,1.02%for recruitment,1.61%for biomass loss and 2.81%for biomass gain,none of them were explained by altitude or soil.Temporal species substitution averaged0.1 in the interval.Altogether,these results suggest that the small-scale variations in altitude and soil likely determine the conditions and resources that drive community assembly and structure,which are expressed by spatial variations along the altitudinal gradient.At the same time,temporal patterns were not influenced by altitude-related environmental variation,resulting in a similar dynamic behaviour across the gradient,suggesting that broad-scale factors may play a more important role than local ones.

Anthropogenic Pressure on Structure and Composition of a Shola Forest in Kerala, India

The montane closed evergreen forests found at altitudes above 1,800 m in the Western Ghats of India possess a distinct vegetation type and are called shola forests. Despite the fact that these forests are located in relatively inaccessible areas, they are still under anthropogenic pressure leading to continued habitat degradation and loss of biomass and biodiversity. A case study was conducted in Mananvan shola, the largest shola forest in Kerala of Western Ghats, to recognize the impact of disturbance on vegetation structure, composition and regeneration pattern, to identify the socio-economic reasons for disturbance and to evolve strategies for its management. In the disturbed part of the forest, dominance of light demanding species in tree, shrub and herb communities has been recorded. Here even the dominance of exotic species in tree seedling, shrub and herb communities is prominent. Skewed girth class distribution of tree community with poor representation by the individuals of girth class 30.1 to 90.0 cm, is also an indication of the collection of small wood and poles from the forest. The RISQ (Ramakrishnan Index of Stand Quality) in the disturbed area of the forest is above 2.0 as against near to 1.0 in relatively undisturbed forest standssuggesting that the disturbance is intensive and thus natural recovery process would be slow. Socio- economic analysis in villages located near the shola forest revealed the fact that the people depended heavily on this forest for their livelihood. Thus, the crux and the success of future management and conservation strategy depend on how one can reduce the dependency of people on the shola vegetation. Enrichment planting in disturbed parts of shola, enhancement of firewood by raising energy plantations, as well as development of lemongrass and firewood based agroforestry systems and reduction of grazing pressure by developing silvopastoral systems are the major strategies for the conservation of these shola forests.

Forest vegetation of Xishuangbanna,south China

Xishuangbanna of southern Yunnan is biogeographically located at a transitional zone from tropical southeast （SE） Asia to subtropical east Asia and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. The region, though surprisingly far from the equator and at a relatively high altitude, has a rich tropical flora and a typical tropical rain forest in the lowland areas. Based on physiognomic and ecological characteristics, floristic composition and habitats combined, the primary vegetation in Xishuangbanna can be organized into four main vegetation types： tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad-leaved forest and tropical monsoon forest. The tropical rain forest can be classified into two subtypes, i.e. a tropical seasonal rain forest in the lowlands and a tropical montane rain forest at higher elevations. The tropical seasonal rain forest has almost the same forest profile and physiognomic characteristics as equatorial lowland rain forests and is a type of truly tropical rain forest. Because of conspicuous similarity on ecological and floristic characteristics, the tropical rain forest in Xishuangbanna is a type of tropical Asian rain forest. However, since the tropical rain forest of Xishuangbanna occurs at the northern edge of tropical SE Asia, it differs from typical lowland rain forests in equatorial areas in having some deciduous trees in the canopy layer, fewer megaphanerophytes and epiphytes but more abundant lianas and more plants with microphyll. It is a type of semi-evergreen rain forest at the northern edge of the tropical zone. The tropical montane rain forest occurs at wet montane habitats and is similar to the lower montane rain forest in equatorial Asia in floristic composition and physiognomy. It is a type of lower montane rain forests within the broader category of tropical rain forests. The tropical seasonal moist forest occurs on middle and upper limestone slopes. It is similar to the tropical montane evergreen broad-leaved forest in the region in physiognomy, but differs from the latter in floristic composition. It is a vegetation type on limestone at high elevations. The monsoon forest in Xishuangbanna is a tropical deciduous forest under the influence of a strong monsoon climate and is considered to be a transitional vegetation type between a tropical rain forest and savanna in physiognomy and distribution. The tropical montane evergreen broad-leaved forest is the main montane vegetation type in the region. It is dominated largely by the families Fagaceae, Euphorbiaceae, Theaceae and Lauraceae. It differs from tropical lower montane rain forests in its lack of epiphytes and in having more abundant lianas and plants with compound leaves. It is considered to be a distinct vegetation type from the northern margin of mainland southeastern Asia, controlled by a strong seasonal climate, based on its floristic and physiognomic characteristics.

A seed rain community in a reforested post-agricultural field and adjacent secondary forest of Mount Papandayan Nature Reserve,West Java,Indonesia

Understanding the mechanisms and barriers to the restoration of degraded land,especially post agriculture,will help provide protocols on effective ways of restoration into functional ecosystems.One of the barriers in early stages of forest restoration is the arrival and availability of propagules.Seed rain and factors affecting it(i.e.,distance to the forest edge,species diversity and surrounding vegetation)were measured in a reforested post-agricultural field and in an adjacent secondary forest.Multivariate g lm analysis was used on the seed rain community data and univariate lm analysis on the most abundant seed captured(i.e.,Schima wallichii(DC.)Korth.).After 8 months of seed rain collection,there was a total of 3596 seeds from eight tree species.Seeds were more abundant and more diverse in the secondary forest(74.9%,8 species)compared to the reforested field(24.1%,2 species).There was a limitation on seed dispersal in reforested field from the adjacent forest.The abundance of S.wallichii seeds determined by the dominance of adult trees(136 trees/ha in the forest and 115 trees/ha in the reforested field).Our study suggests,that after 7 years of planting,the reforested field has received limited seed rain and has not yet recovered.

Response of species and stand types to snow/wind damage in a temperate secondary forest,Northeast China

Snow/wind damage is one of the important natural disturbances in forest ecosystems,especially in a montane secondary forest.However,the effects of snow/wind damage remain unclear which affects the management of these forests.Therefore,we investigated the responses of species,individual tree traits and stand structure to snow/wind damage in a montane secondary forest.Results show that,amongst the canopy trees,Betula costata exhibited the most uprooting,bending and overall damage ratio(the number of damaged stems to the total number of stems in a plot); Quercus mongolica showed the highest breakage ratio and Fraxinus mandshurica and Juglans mandshurica the least overall damage ratios.Among the subcanopy trees,Carpinus cordata,Acer mono,Acer tegmentosum and Acer pseudo-sieboldianum showed the least uprooting and breakage,and the most bending damage.A.pseudo-sieboldianum demonstrated the lowest breakage and highest bending damage ratios.Thesefindings indicate that different species have various sensitivities to snow/wind damage.Larger trees(taller,wider crowns) tend to break and become uprooted,while smaller trees are bent or remain undamaged,suggesting that tree characteristics significantly influence the types of damage from snow and wind.Stands of Q.mongolica and B.costata had the highest damage ratios,whereas A.pseudosieboldianum had the lowest snapping ratio.In summary,the severity and type of snow/wind damage are related to individual tree attributes and stand-level characteristics.Therefore,selection of suitable species(e.g.,shorter,smaller with deep root systems,hard wood,bending resistance and compression resistance) and appropriate thinning are recommended for planting in the montane secondary forests.

Masting effect on alpha and beta avian diversity in fragmented forests of relict?endangered Mexican Beech(Fagus grandifolia subsp.mexicana)

Background:Tropical montane cloud forests are one of the most important hotspots on Earth and show presence of relict-endemic and endangered species,representing about 14%of the total tropical forest worldwide.Synchronous seed production or masting in tropical montane cloud tree species is a widespread reproductive strategy of decidu-ous and evergreen broad-leaved tree associations to decrease costs of reproduction and ensure offspring.Masting event maintains a high avian diversity,which can be modified by phenological process(seed production and non-seed production).Methods:The main aim of this study was to assess alpha and beta avian diversity and whether the composition of the trophic guild modifies among phenological processes and between two fragmented relict-endangered Mexican Beech(Fagus grandifolia subsp.mexicana)forests(Medio Monte and El Gosco)in the Mexican state of Hidalgo.In addi-tion,we evaluated beechnut production.Results:We recorded 36 bird species,11 of them included in some conservation risk status,and 5 endemic species.Alpha diversity values were dissimilar in avian richness(q=0)among phenological processes and between frag-mented beech forests.Avian communities among three phenological processes and between fragmented forests were structurally similar,dominated during immature seeds the Brown-backed Solitaire(granivores-insectivores-frugivores);during mature seeds the White-crowned Parrot(Pionus senilis,granivores-frugivores);and the Dwarf Jay(Cyanolyca nana,insectivores)was abundant during low seed quality.The complementarity index was high among phenological processes and low between forests.We found a high bird turnover value between immature seeds—mature seeds and during mature seeds—low seed quality.Furthermore,a similar pattern was recorded between the two study forests.Seed production showed a high number of undamaged beechnuts in Medio Monte,while in El Gosco beechnuts were attacked by insects.Conclusions:Our results reflect that masting phenological process and contrasting study forests'structure influence the shifts in alpha and beta diversity of seed and non-seed bird consumers.Our study reaffirms the importance of continuing studies throughout masting in all the Mexican Beech forests to address regional efforts in preserving the relict-ecological interactions.

Different environmental factors drive tree species diversity along elevation gradients in three climatic zones in Yunnan,southern China

Elevational patterns of tree diversity are well studied worldwide.However,few studies have examined how seedlings respond to elevational gradients and whether their responses vary across climatic zones.In this study,we established three elevational transects in tropical,subtropical and subalpine mountain forests in Yunnan Province,southern China,to examine the responses of tree species and their seedlings to elevational gradients.Within each transect,we calculated species diversity indices and composition of both adult trees and seedlings at different elevations.For both adult trees and seedlings,we found that species diversity decreased with increasing elevation in both tropical and subalpine transects.Species composition showed significant elevational separation within all three transects.Many species had specific elevational preferences,but abundant tree species that occurred at specific elevations tended to have very limited recruitment in the understory.Our results highlight that the major factors that determine elevational distributions of tree species vary across climatic zones.Specifically,we found that the contribution of air temperature to tree species composition increased from tropical to subalpine transects,whereas the contribution of soil moisture decreased across these transects.

Species Diversity,Distribution,and Microhabitats of Anurans on Mt.Kalo-Kalo of the Mt.Kalatungan Range Natural Park,Bukidnon,Philippines

Anurans are considered good indicators of habitat quality due to their bi-phasic life mode,limited dispersal abilities,and sensitivity to environmental changes brought about by habitat fragmentation,pollution,climate change,and emerging infectious diseases.This study aimed to determine species diversity and local distribution of anurans in lower(1000–1400 masl)and upper(1400–1600 masl)montane forests on Mt.Kalo-Kalo of the Mt.Kalatungan Range Natural Park,Central Mindanao,Southern Philippines by employing standard sampling techniques for amphibians.We recorded a total of 251 individual anurans,representing 12 species during a brief recent study period.Mt.Kalo-Kalo’s upper montane forest has a higher diversity index(H’=1.276)than the lower montane forest(H’=0.851).Despite the very low diversity indices,the level of endemism of anurans was 100%where ten of the recorded species are Mindanao Faunal Region endemics and an additional two species are Philippine endemics.Ansonia muelleri exhibited the highest local abundance and individuals of this species which constituted 73%of individual anurans observed.Most of the species encountered prefer terrestrial and aquatic microhabitats,specifically on the rocks and bank substrates along the rivers and streams.Three species of anurans(Philautus acutirostris,P.poecilius,and Rhacophorus bimaculatus)were strictly found in arboreal microhabitats.Limnonectes magnus and A.muelleri have overlapping microhabitats.Results indicate that for such a short survey and modest sampling effort,the lower and upper montane forests of Mt.Kalo-Kalo support high endemism of anuran species suggesting that conservation efforts continue to be a priority in this unique protected area.

Climate and seasonal rainfall anomalies along an elevational gradient in the El Sira Mountains,Peru,and their impacts on tree radial growth

The explicit purpose of this study was to characterize climate and vegetation along the western slope of the El Sira Mountains(Peru)and evaluate radial tree growth in response to seasonal rainfall anomalies.From May 2011 until September 2015,we monitored radial stem growth of 67 trees using point dendrometers and measured climate within five sites along an altitudinal gradient.The transect extends from lowland terra firme forests,over submontane forests,late and mid successional montane cloud forests up to exposed elfin forests.Monthly rainfall estimates by the TRMM PR satellite(product 3B42)were highly correlated with our rain gauge observations but underestimate rainfall at high altitudes.Different intra-annual tree growth patterns could be identified within each elevational forest type,showing species with strictly seasonal growth,continuous growth or alternating growth patterns independent of the seasons.Stem growth at each site was generally larger during rainy seasons,except for the elfin forest.The rainy season from October 2013 to March 2014 was extraordinarily dry,with only 73%of long-term mean precipitation received,which resulted in reduced radial growth,again with the exception of the elfin forest.This indicates that montane tropical rain forests may suffer from prolonged droughts,while exposed ridges with elfin forests still receive plenty of precipitation and benefit from receiving more solar radiation for photosynthesis.

Conifer establishment after the eruption of the Paricutin volcano in central Mexico

Background:Volcanic eruptions have large effects on forest ecosystems and create new substrates,triggering primary succession processes.The Paricutín volcano,born in central-western Mexico,erupted between 1943 and 1952.After the cessation of the eruptive activity,plant colonization began on the lava flows and tephra deposits,including the conifer species that dominate the surrounding mature forests.This study aims to reconstruct the history of the establishment of conifer trees on the substrates created by the Paricutín eruption.Methods:16 sampling plots were established along three transects with northern,southern,and south-western aspects,located every 250 m from the preserved forest to the volcanic cone.Increment cores from 400 conifer trees were extracted and their age was determined by cross-dating annual tree rings.The order of the species colonization and the tree establishment,abundance,and dominance patterns were characterized.Also,the influence of the distance from the mature forests and the inter-annual climatic conditions on the temporal tree establishment pattern was evaluated.Results:Eight pine and one fir species have been established since 1970,only 18 years after the end of the eruptive period.However,tree establishment increased by 12.9%annually after 1995,with the youngest tree in our sample getting established in 2015.We did not find a well-defined temporal and spatial pattern of species arrival,which suggests that colonization occurred randomly,although the four pine species that were established early became the most abundant and dominant.Tree establishment was not influenced by the distance from the mature forest,and wet inter-annual conditions did not enhance pulses of tree recruitment,exhibiting a continuous tree establishment pattern.Conclusions:Conifer species have shown a great capacity for colonizing volcanic substrates created by the Paricutín eruption,which suggests that tropical montane conifers can regenerate rapidly under high-magnitude disturbances.These findings support the use of these forest species for ecological restoration.

Seed Dynamics in Relation to Gaps in a Tropical Montane Rainforest of Hainan Island,South China:(Ⅰ)Seed Rain

Seed dynamics is an important part of stand dynamics in forest ecosystems. In this paper, 26 gaps were randomly selected to study the influence of gaps on the spatial and temporal patterns of seed rains in a tropical montane rainforest of Hainan Island, South China. Three zones for each gap, including outside gap zone （Non-gap）, transitional gap zone （EG-CG）, and central gap zone （CG）, were designed, and fourseed traps （each lm x lm in size） were placed in each zone. Seed rains were collected by these traps every 10 days from June 2001 to May 2002. Seed rain varied greatly with season and generally exhibited a pattern of unimodal change during the study period： seed abundance and species richness were both greater in the wet season than in the dry season. Gaps significantly influenced the temporal patterns of both species richness and density of seed rains. Gaps had no significant influences on the spatial distribution patterns of seed rain species richness, but significantly affected the spatial distribution pattern of seed rain densities. Among the three different zones of gaps, the outside gap zone generally received more seeds inputs than the two other gap zones.

Gap Dynamics and Tree Species Diversity in a Tropical Montane Rain Forest of Hainan Island,China

Based on investigation of 53 gaps and 25 quadrats (15m×15m each) of non-gap closed stand in an old-growth tropical montane rain forest of Hainan Island, China, canopy disturbance regimes and gap regeneration were studied. Gaps were elliptical in horizontal form, the ratio of long axis /short axis was about 1.4. Percentage of expanded gaps (EG) and canopy gaps (CG) area in the landscape were 53.5% and 25.2% respectively. EG ranged from 31.4 m2 to 488.2m2 and CG/rom 14.9m2 to 354.2m2, their average sizes ...