Patterns Of Tree Species Composition Research Articles

Tree Species Diversity and Stand Structure in Selected Forest Patches of Marilog Forest Reserve, Southern Philippines


 Tree species diversity and stand structure investigations were conducted in the forest patches of Barangay Baganihan (site 1) and Mt. Malambo in Barangay Datu Salumay (site 2), Marilog District, Southern Philippines. Thirty-three 20 × 20 m plots were established at 1,197-1,345 masl in the sites. A total of 900 individuals belonging to 33 families, 43 genera, and 65 species of trees were recorded. Analyses of data revealed that the two sites could be categorised as montane forests based on the forest structure and species composition. Palaquium philippense (Perr.) C.B. Rob., Syzygium tula (Merr.) Merr., and Astrocalyx calycina (S.Vidal) Merr. obtained the highest species importance value index in site 1, while Palaquium sp., P. philippense, and Lithocarpus caudatifolius (Merr.) Rehder in site 2. Shannon-Weiner indices (H’) in sites 1 and 2 are relatively low with H’ = 1.22 and H’ = 1.38, respectively. A total of eight threatened species were recorded, viz., A. calycina as endangered; Agathis philippinensis Warb., Becarianthus pulcherrimus (Merr.) Maxw., Camellia lanceolata (Blume) Seem., Dillenia megalantha Merr., P. philippense and Shorea contorta S.Vidal as vulnerable; and Cinnamomum mercadoi S.Vidal as other threatened species. A total of 14 endemic species of trees were also recorded in the study sites. The biodiversity in the two sites is under severe threat due to the different anthropogenic disturbances. A new population of A. calycina, a monotypic genus in the Philippines, was collected and the flowers were documented for the first time after a century. The present study is significant since it would help elucidate the patterns of tree species composition and diversity in the forest patches of Barangay Baganihan and Mt. Malambo in Barangay Datu Salumay. Further, this paper adds to the rich biological diversity in Mt. Malambo by supporting its great potential as an ecotourism site.

The presence of peat and variation in tree species composition are under different hydrological controls in Amazonian wetland forests

AbstractThe peat‐forming wetland forests of Amazonia are characterized by high below‐carbon stocks and supply fruit, fibres and timber to local communities. Predicting the future of these ecosystem services requires understanding how hydrological conditions are related to tree species composition and the presence, or absence, of peat. Here, we use continuous measurements of water table depth over 2.5 years and manual measurements of pore‐water pH and electrical conductivity to understand the ecohydrological controls of these variables across the large peatland complex in northern Peruvian Amazonia. Measurements were taken in permanent forest plots in four palm swamps, four seasonally flooded forests and four peatland pole forests. All trees ≥10 cm diameter were also measured and identified in the plots to assess floristic composition. Peat occurs in eight of these twelve sites; three seasonally flooded forests and one palm swamp are not associated with peat. Variation in tree species composition among forest types was linked to high flood levels (maximum flooding height) and pH: seasonally flooded forests experience high flood levels (up to 3.66 m from the ground surface) and have high pH values (6–7), palm swamps have intermediate flood levels (up to 1.34 m) and peatland pole forests experience shallow flooding (up to 0.28 m) and have low pH (4). In contrast, the presence of peat was linked to variation in maximum water table depth (i.e. the depth to which the water table drops below the ground surface). Surface peat is found in all forest types where maximum water table depth does not fall >0.55 m below the ground surface at any time. Peat formation and variation in tree species composition therefore have different ecohydrological controls. Predicted increases in the frequency and strength of flooding events may alter patterns of tree species composition, whereas increases in drought severity and declines in minimum river levels may pose a greater risk to the belowground carbon stores of these peatland ecosystems.

On the floristic identity of Amazonian vegetation types

AbstractThe Amazon forest is far from uniform, containing different forest types and even savannas, but quantitative analyses of this variation are lacking. Here, we applied ordination analyses to test the floristic differentiation among Amazonian vegetation types using data for virtually all known tree species occurring in the Amazon (8224), distributed across 1584 sites. We also performed multiple regressions to assess the role of climate and substrate in shaping continental‐scale patterns of community composition across Amazonia. We find that the traditional classification of Amazonian vegetation types is consistent with quantitative patterns of tree species composition. High elevation and the extremes of substrate‐related factors underpin the floristic segregation of environmentally “marginal” vegetation types and terra firme forests with climatic factors being relatively unimportant. These patterns hold at continental scales, with sites of similar vegetation types showing higher similarity between them regardless of geographic distance, which contrasts with the idea of large‐scale variation among geographic regions (e.g., between the Guiana Shield and southwestern Amazon) representing the dominant floristic pattern in the Amazon. In contrast to other tropical biomes in South America, including the Mata Atlântica (second largest rain forest biome in the neotropics), the main floristic units in the Amazon are not geographically separated, but are edaphically driven and spatially interdigitated across Amazonia. Two thirds of terra firme tree species are restricted to this vegetation type, while among marginal vegetation types, only white‐sand forests (campinaranas) have a substantial proportion of restricted species, with other vegetation types sharing large numbers of species.

Environmental filtering determines patterns of tree species composition in small mountains of Atlantic Central African forests

The determinants of patterns of plant species composition on small mountains are poorly known, especially in Central Africa. We aimed here to identify variation in tree species composition throughout the Ngovayang Massif (southern Cameroon) and determine the relative contributions of environmental factors and spatial autocorrelation in shaping tree species composition. Vegetation surveys were conducted in fifteen 1-ha (100 m × 100 m) permanent plots established along a transect from lowland (200 m) to submontane forests (900 m) in which all trees with a diameter (dbh) ≥ 10 cm were inventoried. Data were investigated using ordination methods (Correspondence Analysis and Canonical Correspondence Analysis). At the local scale, the most important variable in determining tree species composition patterns was slope exposure, followed by distance from the ocean and altitude. Together, these environmental variables explained 28% of floristic variation among plots, and the spatial structure almost disappeared when the effects of these variables were removed. Spatial autocorrelation analysis showed that spatial variables (geographic coordinates of the plots) or geographic distance between plots explained only 1% of the total initial variance. Residual spatial variation not explained by the environmental variables probably reflects the history of vegetation and the effects of other climatic variables that were not included in this study. Floristic variation in the Ngovayang Massif is due to strong environmental heterogeneity. The sensitivity of floristic composition to environmental variables such as slope orientation and altitude suggests that tree species composition may shift with expected climate changes, such as changes in the movement of air masses, increase in mean annual temperatures or increasing severity of the dry season. Our study highlights the need for systematic on-the-ground measurements of climate variables in tropical montane areas in order to better understand the current climate regime and serve as a basis for modelling future changes.

Diversity and structural composition of species in dipterocarp forests: a study from Fasiakhali Wildlife Sanctuary, Bangladesh

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large, old Garjan (Dipterocarpus spp.) trees. The present study assessed composition, structure and diversity of the species in this protected area. A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 families. The forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance indices. Dipterocarpus turbinatus was the most dominant species with maximum relative density, frequency, dominance, and importance value index. Syzygium firmum and Tectona grandis followed in terms of dominance. The structural composition indicated higher number of individuals in the medium growth classes (41 to < 511 cm DBH and 16–20 m height ranges), whereas D. turbinatus was the only species that dominated most of the growth classes. Poor stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation, increased grazing and encroachments. This study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of Bangladesh. It will also contribute to identifying threatened plants to undertake D. turbinatus based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.

Tree composition and abundance patterns differ in two watersheds of Forest Park, a large Pacific Northwest urban forest

We compared differences in patterns of tree species composition and abundance in a set of six permanent research plots designated in paired watersheds in a large forested park in Portland, Oregon: one proximal to the urban area and the other proximal to rural areas. All were established in mixed conifer-deciduous stands with similar tree age classes, orientation, topography and other environmental variables. One old-growth plot reference was included in each watershed. The urban plots have experienced periodic disturbances and are continually subjected to continual low-impact disturbances. The urban plots, in contrast to rural plots and to their reference old-growth plots, showed significant differences in tree species composition and ages, sapling numbers, and amount of coarse woody debris. NMDS and nonparametric ANOVA revealed the urban plots as having the greatest ecological distance from all other plots. Soil disturbance, lack of O- and A-horizons, and coarse woody debris were disturbance indicators. Given current patterns of regeneration, the urban plots will be dominated in the future by hardwood species. This projection, when compared with the proximate old-growth patch and with historical records for the urban end of the park, has no historic antecedent. These conclusions are concurrent with findings for other urban forests, where early successional species dominate over long periods of time. The described ecological trends, especially with the domination of invasive species, reflect the urban condition of the forest and constitute a novel state.

Effects of topography and spatial processes on structuring tree species composition in a diverse heterogeneous tropical karst seasonal rainforest

Aggregated patterns of tree species originate either from the physical forcing of habitat heterogeneity or from community processes. In both cases, spatial structuring plays a functional role in ecosystems. This study examines the spatial patterns of tree species, and discusses the degree to which variation in species distribution patterns depends on topographic variation. We first analyzed the spatial distribution patterns of tree species by using the univariate pair correlation function. We used redundancy analysis to identify the main structures explained by the measured topographic variables. Then, we used variation partitioning in combination with Moran’s eigenvector maps and seven topographic variables to determine the relative importance of the effects of pure topographical, pure spatial, and spatially structured environmental processes on spatial patterns of tree species composition in a large-scale stem-mapping plot located in a diverse heterogeneous tropical karst seasonal rain forest of south China. Although aggregated distribution was the dominant pattern for tree species as we expected in this tropical karst forest, the degree of aggregation was lower than in other tropical or subtropical forests. Most species showed random patterns after controlling for habitat heterogeneity in a parametric heterogeneous Poisson process null model. The seven topographical variables explained about 16.7%, 31.0% and 47.2% of the total variance in species abundances by redundancy analysis for cell sizes of 10m×10m, 20m×20m and 50m×50m, respectively. The pure spatial component was most important at the three spatial scales, which accounted for about one-third of total variance in species composition, while the spatially independent habitat contributed a negligible effect. This indicated that the overall evidence for topographic controls of the tropical tree species spatial pattern was strong, but the explanatory power of the topographic variables was negligible compared to the total variation of pure spatial processes, especially the broad-scale space. The results suggest that topographical and neutral progresses jointly contribute to the maintenance of species composition, and their relative importance varies with spatial scale in the Nonggang tropical karst seasonal rain forest.

A general framework to describe the alteration of natural tree species composition as an indicator of forest naturalness

The alteration of natural tree species composition is defined as the deviation of the current tree species composition from that of the natural state. It can be used as a measure of human influence on forest vegetation, and thus as an indicator of the naturalness of forest vegetation. The aim of the study was to develop a standard procedure for estimating the alteration of natural tree species composition, to explain factors driving alteration and to examine its significance for susceptibility of forest stands to natural disturbances. The alteration of natural tree species composition was estimated for the Dinaric region (5556km2, Slovenia) by the Robič Index of Dissimilarity (RID), ranging from 0 (completely natural) to 100 (completely altered). The index was calculated on the compartment level (24ha each on average) with data on current and potential natural forest vegetation. The influence of human activities on tree species alteration was examined by using topographic and accessibility variables. The susceptibility of forest stands to natural disturbances was analysed with data on sanitary felling. In the study area, the natural tree species composition of forest stands is moderately preserved; the average value of RID was 50.05, ranging from 1.76 to 100, and the coefficient of variation was 0.49. The alteration of the natural tree species composition of forest stands is primarily the result of forest management and past land use, conditioned either by topography or accessibility of forests. The degree of alteration of tree species composition decreased along the gradients of rockiness, inclination and elevation. A greater degree of alteration appeared on the slopes of intermediate and south facing aspects than on north facing slopes, and in areas that were closer to the forest edge. A higher level of alteration significantly increases the susceptibility of forest stands to natural disturbances. The procedure represents a novel approach in modelling the alteration (naturalness) of tree species composition of forest vegetation. It is applicable at different spatial scales and fosters an understanding of the patterns of tree species composition under the influence of human activity across forest landscapes.

Patterns of tree species composition at watershed-scale in the Amazon ‘arc of deforestation’: implications for conservation

SUMMARYThe loss of biodiversity in transitional forests between the Cerrado and Amazonia, the two largest neotropical phytogeographic domains, is an issue of great concern. This extensive region is located within the ‘arc of deforestation’ zone where tropical forests are being lost at the fastest rate on the planet, but floristic diversity and variation among forests here is still poorly understood. We aimed to characterize the floristic composition of forests in this zone and explored the degree and drivers of differentiation within and across Araguaia and Xingu watersheds. In 10 sites we identified all trees with diameter ≥10 cm; these totaled 4944 individuals in 257 species, 107 genera and 52 families. We evaluated the data for multivariate variation using TWINSPAN and DCA to understand the species distribution among sites. There was a larger contribution from the Amazonian flora (169 species) than that of the Cerrado (109) to the transitional forests. Remarkably, 142 species (55%) were restricted to only one sampling site, while 29 species (&gt;16%) are endemic to Brazil, suggesting potentially large loss of species and unique forest communities with the loss and fragmentation of large areas. Our results also suggest that watersheds may be a critical factor driving species distribution among forests in the Amazonian–Cerrado transition zone, and quantifying their role can provide powerful insight into devising better conservation strategies for the remaining forests.

Tree diversity, stand structure, and community composition of tropical forests in Eastern Ghats of Andhra Pradesh, India

Species diversity and density of trees were assessed in four 1-ha plots (at 457–925 m in elevation) in the Eastern Ghats of the Andhra Pradesh region comprising mostly of tropical deciduous forests based on a census of all trees with girth at breast height ≥ 15cm. We compared tree community characteristics like stem density, basal area, diversity, and species composition of four plots using a tree dataset of eight belt transects (5 m×1000 m) in the study area. A total of 2,227 individuals of 44 families, 98 genera, and 129 species were recorded. Combretaceae, Euphorbiaceae, and Anacardiaceae, showed the greatest importance value index. It was noticed that the most species were contributed by Euphorbiaceae and the tree density varied from 435 ha–1 to 767 ha–1 with an average basal area of 25.82 m2/ha. Shannon–Weiner index (H') ranged from 3.76 to 3.96, the Simpson index ranged from 0.96 to 0.97, evenness index ranged from 0.60 to 0.78, and species richness index ranged from 10.04 to 11.24. At present the biodiversity of these forests are under threat due to the anthropogenic and upcoming mining activities. The present study will help us to understand the patterns of tree species composition and diversity in the Eastern Ghats of India.

Revisiting Patterns of Tree Species Composition and their Driving Forces in the Atlantic Forests of Southeastern Brazil

AbstractThe elucidation of phytogeographic patterns and their drivers in biodiversity hotspots is essential to the study of ecology and the conservation of these areas. In 2000, an important study by Oliveira‐Filho and Fontes led to changes in the paradigms that define our understanding of the Atlantic Forest (Brazil). Here, our aim was to revisit this study using a more comprehensive set of environmental predictors, an updated and much larger tree species dataset and checklist, and more refined data analyses. We performed exploratory and confirmatory analyses, including the modeling of the spatial components with Moran's Eigenvector Maps, using data from 483 sites in southeastern Brazil, which encompass a total of 3546 species and 33 geo‐climatic variables. We observed strong floristic similarities between rain‐ and seasonal forests and a species distribution continuum across the main gradients. The environmental and spatial variables were significantly correlated with floristic patterns, and we demonstrated that the tree flora of the seasonal forests should no longer be considered a simple subset of the rain forest flora. The findings of the original paper were not only confirmed but we also unveiled additional, important phytogeographic patterns. We also reinforced the main conclusion of the paper that the Atlantic Forest concept must encompass all of the forest types east of the dry corridor in South America, a designation of utmost importance for the conservation of this biodiversity hotspot.

Patterns of tree species composition across tropical African forests

AbstractAimIn this study we identified large‐scale variation in tree species composition across tropical African forests and determined the underlying environmental and historical factors.LocationTropical forests from Senegal to Mozambique.MethodsDistribution data were gathered for 1175 tree species in 455 sample sites scattered across tropical Africa, including all types of tropical forests (wet, moist, dry, and lowland to moderate elevation montane forests). The value of elevation and 19 climatic variables extracted from the BIOCLIM data set were assigned to each sample site. We determined the variation in species composition using correspondence analysis and identified the environmental correlates. We defined floristic clusters according to species composition and identified the characteristic species using indicator analysis.ResultsWe identified a major floristic discontinuity located at the Albertine rift that separated the dry, moist and wet forests of West and Central Africa (the entire Guineo‐Congolian Region) from the upland and coastal forests of East Africa. Except for the Albertine Rift, we found no evidence to support the other proposed floristic discontinuities (Dahomey Gap etc.). We detected two main environmental gradients across tropical African forests. The rainfall gradient was strongly correlated with the variation in tree species composition in West and Central Africa. The elevation/temperature gradient highlighted the major floristic differences within East Africa and between East Africa and the Guineo‐Congolian Region, the latter being most probably due to the geological disruption and associated climatic history of the East African uplift.Main conclusionsWe found floristic evidence for three main biogeographical regions across the tropical African forests, and described six floristic clusters with particular environmental conditions within these regions: Coastal and Upland for East Africa, Dry and Wet‐Moist for West Africa, and Moist and Wet for Central Africa.

Characteristics and Growing Stocks Volume of Forest Stand in Dry Temperate Forest of Chilas Gilgit-Baltistan

Chilas forest sub division in Diamer district, of Gilgit-Baltistan is located at northern regions of Pakistan. We estimated tree density, diameter, height and volume of the dominant tree species in four blocks (Thore, Chilas, Thak Niat and Gunar) of Chilas forest sub division. The tree density of deodar was maximum with average 26 tree·ha-1 and minimum was of Chalgoza 4 trees·ha-1. The maximum average height showed by the dominant species (Fir, Kail, Deodar, and Chilgoza) of the study area to be 20.40, 16.06, 12.24 and 12.12 m respectively. Moreover the average maximum volume attained by the Kail, Fir, Deodar and Chalgoza trees was 1.92, 1.57, 0.46 and 0.291 m3·tree-1 respectively. Regression analysis was carried out to determine the relationship between diameter (cm), height (m), tree density (trees·ha-1) and volume (m3·ha-1). The findings of the study will help the future scientific management of the forest for sustained yield. The study also provides information about the unexplored growing stock and structure of the forests. Additionally, this study will help to understand the patterns of tree species composition and diversity in the northern part of Pakistan with dry temperate climate.

Relationships between urban tree communities and the biomes in which they reside

AbstractQuestionsClimate strongly influences the composition of natural plant communities, but a variety of human activities might release plants in urban areas from some of these climatic constraints. (1) After controlling for minimum temperature, is urban tree species composition related to biome? (2) Do any such patterns result solely from the presence of native species in urban floras? (3) Which climatic, demographic and economic variables are predictive of urban tree species composition?LocationContinental USA.MethodsWe investigated patterns of tree species composition in small cities across the continental USA, specifically exploring relationships to surrounding biomes and their accompanying temperature and precipitation regimes, as well as to key demographic and economic variables. We estimated urban tree species composition by surveying tree experts in randomly selected cities that were stratified by minimum temperature (i.e. ‘hardiness zone’) and biome, and constrained to similar population sizes. We then used non‐metric multidimensional scaling to investigate relationships between urban tree species composition, biome classification, native status, individual climate variables and several anthropogenic factors.ResultsWe found that urban tree communities were consistently related to the surrounding biome, even after controlling for minimum temperatures. These communities could also be predicted by several individual climatic variables (in models that focused solely on the role of climate as well as models that simultaneously considered key anthropogenic factors). In addition, most of these general patterns were still present when we exclusively examined non‐native species. We were unable to identify specific climatic and anthropogenic variables of broad importance because the most predictive variables were highly dependent upon the specific analysis.ConclusionsOur results demonstrate that, despite substantial human influence, urban tree communities (including their non‐native components) are related to the same climate factors that shape wildland plant communities.

Impacts of selective logging on tree diversity across a rainforest landscape: the importance of spatial scale

Selective logging of tropical forests imposes spatial pattern on the landscape by creating a mosaic of patches affected by different intensities of disturbance. To understand the ecological impacts of selective logging it is therefore necessary to explore how patterns of tree species composition are affected by this patchy disturbance. This study examines the impacts of selective logging on species composition and spatial patterns of vegetation structure and tree diversity in Sabah, Borneo. We compare tree diversity between logged and unlogged forest at three scales: species richness within plots, species turnover among plots, and total species richness and composition of plots combined. Logging had no effect on tree diversity measured at the smallest scale. Logged forest had a greater rate of species turnover with distance, so at a large spatial scale it supported more tree species than the relatively homogeneous unlogged area. Tree species composition also differed significantly between the two types of forest, with more small dipterocarps and large pioneers in logged forest, and more large dipterocarps in unlogged forest. Our results emphasize the importance of sampling at a sufficiently large scale to represent patterns of biodiversity within tropical forest landscapes. Large areas of production forest in SE Asia are threatened with conversion to commercial crops; our findings show that selectively logged forest can retain considerable conservation value.

Simulating Landscape-Level Effects of Constraints to Public Forest Regeneration Harvests due to Adjacent Residential Development in Northern Wisconsin

Abstract Residential development in rural forests is currently one of the most prominent land use changes in the United States. Such development can have important effects on ecosystem processes and landscape patterns. It can also constrain forest management on public lands, influencing tree species composition and age structure at the landscape scale. We used the forest landscape simulation model LANDIS-II to analyze changes to the landscape patterns of tree species composition, age structure, windthrow disturbance, and aboveground live biomass across a range of constraints to public forest timber harvests on a northern Wisconsin landscape. Our results demonstrate that decreasing harvest area through the use of buffers reduces the dominance of early-successional species, increases the dominance of mid to later-successional species, and shifts the stand age distribution within the landscape toward older forests. These buffers increase the spatial heterogeneity of dominant species and age structure at the landscape scale, and lead to more windthrow disturbance. We believe that our study can inform policymakers, forest managers, and scientists about potential long-term landscape-level effects of interaction between residential development and forest management. FOR. SCI. 51(6):616–632.