Diversity Of Tree Communities Research Articles

Diversity and aboveground biomass in three tropical forest types in the Dja Biosphere Reserve, Cameroon

AbstractWe present tree community diversity, species composition, basal area and aboveground biomass of three forest types in the Dja Biosphere Reserve, in South‐East Cameroon, part of the contiguous tropical forest of the Congo Basin. A total of fourteen, 1 ha, plots were established in heterogeneous terra firme forests (TFF), Gilbertiodendron dewevrei forests (GDF) and periodically flooded forests (PFF). A total of 281 tree species with diameter ≥10 cm were recorded. The Shannon diversity index was significantly higher in TFF (5.7 ± 0.28) and PFF (5.6 ± 0.23) than in GDF (2.29 ± 0.48) (ANOVA, F2,11 = 139.75, P < 0.001). While tree density did not differ between forest types (F2,11 = 3.50, P = 0.06), basal area differed significantly (F2,11 = 7.38, P = 0.009), as did aboveground biomass (F2,11 = 17.95, P < 0.001). Mean AGB values were respectively, 596.1 ± 62.24, 401.67 ± 58.06 and 383.14 ± 61.91 Mg ha−1 in GDF, TFF and PFF. Variation in the abundance of trees with large diameter was the main reason for these differences. Few dominant species made the greatest contribution to the AGB. G. dewevrei, accounted for 83% of AGB in GDF, Penthaclethra macrophylla for 9.9% in TFF and Uapaca heudolotii for 10.6% in PFF. The importance of preserving G. dewevrei forest in the context of ‘Reducing Emissions from Deforestation and forest Degradation’ (REDD) policies is discussed.

Influence of soils and topography on Amazonian tree diversity: a landscape-scale study

Question: How do soils and topography influence Amazonian tree diversity, a region with generally nutrient-starved soils but some of the biologically richest tree communities on Earth? Location: Central Amazonia, near Manaus, Brazil. Methods: We evaluated the influence of 14 soil and topographic features on species diversity of rain forest trees (≥10 cm diameter at breast height), using data from 63 1-ha plots scattered over an area of ∼400 km2. Results: An ordination analysis identified three major edaphic gradients: (1) flatter areas had generally higher nutrient soils (higher clay content, carbon, nitrogen, phosphorus, pH and exchangeable bases, and lower aluminium saturation) than did slopes and gullies; (2) sandier soils had lower water storage (plant available water capacity), phosphorus and nitrogen; and (3) soil pH varied among sites. Gradient 2 was the strongest predictor of tree diversity (species richness and Fisher's α values), with diversity increasing with higher soil fertility and water availability. Gradient 2 was also the best predictor of the number of rare (singleton) species, which accounted on average for over half (56%) of all species in each plot. Conclusions: Although our plots invariably supported diverse tree communities (≥225 species ha−1), the most species-rich sites (up to 310 species ha−1) were least constrained by soil water and phosphorus availability. Intriguingly, the numbers of rare and common species were not significantly correlated in our plots, and they responded differently to major soil and topographic gradients. For unknown reasons rare species were significantly more frequent in plots with many large trees.

Diversity of tree communities in Mount Patuha region, West Java

Junaedi DI, Mutaqien Z (2010) Diversity of tree communities in Mount Patuha region, West Java. Biodiversitas 11: 75-81. Treevegetation analysis was conducted in three locations of Mount Patuha region, i.e. Cimanggu Recreational Park, Mount Masigit Protected Forest, and Patengan Natural Reserve. Similarity of tree communities in those three areas was analyzed. Quadrant method was used to collect vegetation data. Morisita Similarity index was applied to measure the similarity of tree communities within three areas. The three areas were dominated by Castanopsis javanica A. DC., Lithocarpus pallidus (Blume) Rehder and Schima wallichii Choisy. The similarity tree communities were concluded from relatively high value of Similarity Index between three areas. Cimanggu RP, Mount Masigit and Patengan NR had high diversity of tree species. The existence of the forest in those three areas was needed to be sustained. The tree communities data was useful for further considerations of conservation area management around Mount Patuha.Key words: Mount Patuha, tree communities, plant ecology, remnant forest

Sapling herbivory, invertebrate herbivores and predators across a natural tree diversity gradient in Germany’s largest connected deciduous forest

Tree species-rich forests are hypothesised to be less susceptible to insect herbivores, but so far herbivory–diversity relationships have rarely been tested for tree saplings, and no such study has been published for deciduous forests in Central Europe. We expected that diverse tree communities reduce the probability of detection of host plants and increase abundance of predators, thereby reducing herbivory. We examined levels of herbivory suffered by beech (Fagus sylvatica L.) and maple saplings (Acer pseudoplatanus L. and Acer platanoides L.) across a tree species diversity gradient within Germany’s largest remaining deciduous forest area, and investigated whether simple beech or mixed stands were less prone to damage caused by herbivorous insects. Leaf area loss and the frequency of galls and mines were recorded for 1,040 saplings (>13,000 leaves) in June and August 2006. In addition, relative abundance of predators was assessed to test for potential top-down control. Leaf area loss was generally higher in the two species of maple compared to beech saplings, while only beech showed a decline in damage caused by leaf-chewing herbivores across the tree diversity gradient. No significant patterns were found for galls and mines. Relative abundance of predators on beech showed a seasonal response and increased on species-rich plots in June, suggesting higher biological control. We conclude that, in temperate deciduous forests, herbivory–tree diversity relationships are significant, but are tree species-dependent with bottom-up and top-down control as possible mechanisms. In contrast to maple, beech profits from growing in a neighbourhood of higher tree richness, which implies that species identity effects may be of greater importance than tree diversity effects per se. Hence, herbivory on beech appeared to be mediated bottom-up by resource concentration in the sampled forest stands, as well as regulated top-down through biocontrol by natural enemies.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-009-1304-2) contains supplementary material, which is available to authorised users.

Tree Community Change across 700 km of Lowland Amazonian Forest from the Andean Foothills to Brazil

ABSTRACTWe describe patterns of tree community change along a 700‐km transect through terra firme forests of western Amazonia, running from the base of the Andes in Ecuador to the Peru–Brazil border. Our primary question is whether floristic variation at large scales arises from many gradual changes or a few abrupt ones. Data from 54 1‐ha tree plots along the transect support the latter model, showing two sharp discontinuities in community structure at the genus level. One is located near the Ecuador–Peru border, where the suite of species that dominates large areas of Ecuadorean forest declines abruptly in importance to the east. This discontinuity is underlain by a subterranean paleoarch and congruent with a change in soil texture. A second discontinuity is associated with the shift from clay to white sand soils near Iquitos. We hypothesize that the first discontinuity is part of an edaphic boundary that runs along the Andean piedmont and causes a transition from tree communities preferring richer, younger soils near the base of the Andes to those preferring poorer, older soils farther east. Because the floristic changes observed at this discontinuity are conserved for large distances to the east and west of it, the discontinuity is potentially key for understanding floristic variation in western Amazonia. The significant floristic turnover at the Ecuador–Peru border suggests that the only large protected area in the region—Ecuador's Yasuní National Park—is not adequate protection for the very diverse tree communities that cover vast areas of northern Peru.

Tree spacing and area of competitive influence do not scale with tree size in an African rain forest

AbstractQuestions:Is the area of influence of individual trees determined by tree size? Does competition, inferred from spatial pattern between neighbouring trees, affect adult tree spacing patterns in an tropical forest? At what size‐class or stage is competition between neighbours most likely to affect adult tree spacing patterns?Location:Kibale National Park, western Uganda.Methods:Relationships between focal tree size and nearest neighbour distance, size, density, and species in a 4‐ha permanent plot, using point pattern analyses.Results:We found non‐random patterns of distribution of nearest tree neighbours (stems > 10 cm DBH). Independent of identity, tree density was highest and neighbours were regularly spaced within 3–5m of an individual. Tree densities were lower and relatively constant at distances >5m and neighbours were typically randomly spaced. In general, conspecific patterns conformed to the latter trends. Thus, individual area of influence was small (within a radius of 3–5 m). Rarer species were more clumped than common species. Weak competitive thinning occurred among more densely packed small trees (<20 cm DBH), and rapidly disappeared with increasing tree size and distance from an individual. The clumping and density of individuals was not significantly affected by tree size.Conclusions:Negative effects of competition among trees are weak, occur within the crown radius of most individuals, and are independent of adult tree size and identity. The density of neighbouring trees (aggregation) did not decline with increasing focal tree size at either the conspecific or the community level and tree diameter (tree size) was not a good estimator of the implied competitive influence of a tree. Mechanisms operating at the recruitment stage may be important determinants of adult tree community diversity and spacing patterns.

Rapid decay of tree-community composition in Amazonian forest fragments.

Forest fragmentation is considered a greater threat to vertebrates than to tree communities because individual trees are typically long-lived and require only small areas for survival. Here we show that forest fragmentation provokes surprisingly rapid and profound alterations in Amazonian tree-community composition. Results were derived from a 22-year study of exceptionally diverse tree communities in 40 1-ha plots in fragmented and intact forests, which were sampled repeatedly before and after fragment isolation. Within these plots, trajectories of change in abundance were assessed for 267 genera and 1,162 tree species. Abrupt shifts in floristic composition were driven by sharply accelerated tree mortality and recruitment within approximately 100 m of fragment margins, causing rapid species turnover and population declines or local extinctions of many large-seeded, slow-growing, and old-growth taxa; a striking increase in a smaller set of disturbance-adapted and abiotically dispersed species; and significant shifts in tree size distributions. Even among old-growth trees, species composition in fragments is being restructured substantially, with subcanopy species that rely on animal seed-dispersers and have obligate outbreeding being the most strongly disadvantaged. These diverse changes in tree communities are likely to have wide-ranging impacts on forest architecture, canopy-gap dynamics, plant-animal interactions, and forest carbon storage.

Spatial Patchiness of Litter, Nutrients and Macroinvertebrates during Secondary Succession in a Tropical Montane Cloud Forest in Mexico

We test the hypothesis that secondary succession in Tropical Montane Cloud Forest (TMCF) in Mexico is accompanied by an increase in the spatial structuring of litter resources, soil nutrient concentrations and the soil macroinvertebrate community at a within-plot scale (5–25 m). This increased spatial structuring is expected because secondary succession in these forests is associated with an increase in the diversity of trees that dominate the canopy. If each tree species generates a particular soil environment under its canopy, then under a diverse tree community, soil properties will be spatially very heterogeneous. Tree censuses and grid sampling were performed in four successional stages of a secondary chronosequence of TMCF. Variography was used to analyse spatial patterns in continuous variables such as nutrient concentrations, while Spatial Analysis by Distance Indices (SADIE) was applied to determine patchiness in the distribution of soil macroinvertebrate taxa. Secondary succession was found to be accompanied by the predicted increase in the spatial structuring of litter resources and the macroinvertebrate community at the within-plot scale. Spatial patterns in the macroinvertebrate community only became evident for all taxa in the oldest forest (100 years old). Patches with low Ca and Mg concentrations in early successional soils were associated with patches where pine litter was most abundant while those with low P concentrations in late successional stages were associated with patches where oak litter was most abundant. Results suggest that anthropogenic disturbance aboveground promotes a more homogeneous resource environment in the surface soil, which compared to older forests, sustains a less diverse and less spatially structured macroinvertebrate community.

A COMPARISON OF TREE SPECIES DIVERSITY IN TWO UPPER AMAZONIAN FORESTS

We inventoried two Amazonian tree communities separated by ;1400 km of continuous lowland tropical forest, in an effort to understand why one was more diverse than the other. YasuniNational Park, near the equator in eastern Ecuador, has one of the most diverse tree communities in the world. Manu National Park, at 128 S in Peru's Madre de Dios region, is only moderately diverse by upper Amazonian standards. Following the field inventories, a database of morphological, ecological, and other traits was compiled from the taxonomic literature for 1039 species from the plots. Our goals were (1) to describe how terra firme tree communities at the two sites differed in composition, diversity, and structure; (2) to characterize the ''extra'' species responsible for the higher diversity at Yasuni ´; and (3) to assess, in the light of those observations, some explanations for why forests near the equator are so diverse. Yasunihas ;1.4 times as many tree species as Manu at all three spatial scales we examined: local (1 ha), landscape (,10 000 km 2 ), and regional (,100 000 km 2 ). Yasuni ´ samples contain more families and genera, more individual trees per unit area, and a larger proportion of small trees. Tree species at Yasunihave smaller stature, larger leaves, larger seeds, and smaller geographic and altitudinal ranges than those at Manu, and dispropor- tionate increases in species diversity are observed within the Myrtaceae, Lauraceae, Me- lastomataceae, and several other families. Community structures were strikingly similar, with the same species (Iriartea deltoidea, a palm) dominating both sites at identical den- sities. Common species at Yasunioccur at the same densities as equally ranked species at Manu, but there are substantially more very rare species at Yasuni ´. The poorer tree flora is not a nested subset of the richer tree flora, though a majority of species in each inventory do occur at the other site. Several models that offer explanations for geographic variation in tropical tree species diversity are assessed in light of these data. Most do a poor job of accounting for the patterns revealed by the inventories. We speculate that the most important factor in pro- ducing the higher diversity in Yasuniis its rainier, aseasonal climate, and we discuss two specific rainfall-related mechanisms that appear to be supported by the data: (1) year-round water availability allowing more species to persist in the understory at Yasuniand (2) a newly described ''mixing effect'' related to the higher stem density there.

Patterns of β-diversity in a Mexican tropical dry forest

Abstract Patterns of β-diversity in a highly diverse tropical dry forest tree community are described; the contribution of environmental heterogeneity and distance to β-diversity was assessed. Significant differences in elevation, insolation, slope and soil water holding capacity (p < 0.01), variables related to water availability, were found among 8 30 m × 100 m transects laid along contrasting slopes of a system of three parallel microbasins. A gradient in elevation and insolation was found within north-facing transects, among 10 m × 10 m sites; south-facing transects showed an elevation gradient while crest transects showed a gradient in water holding capacity. In total 119 species were registered, with 27 to 64 species per transect, and 4 to 16 species per site. A large β-diversity was found among and within transects; two indices of β-diversity consistently showed a higher β-diversity within transects than among them. Among transects, 64% of the variance in species composition could be attributed to ...

Diversity and structure of tropical rain forest of Tutuila, American Samoa: effects of site age and substrate

We report tree community diversity, guild composition, and forest structure from three 1.2 ha (100 m 120 m) permanent forest research plots on Tutuila, American Samoa, an isolated volcanic island in the South Pacific Ocean. Plots were established in three habitat types of lowland hill forest: two in mature tracts that differed in substrate type (talus vs non-talus), and a third in a 30‐40 year-old abandoned plantation on non-talus soil. We encountered a total of 57 tree species10 cm dbh. Richness was similar across sites, but composition differed substantially. We were able to classify with confidence 24 tree species into four distinct guilds based on foresttype preference: early successional or persistent successional (disturbed forest), generalist (no preference), or mature-phase. Sample size limitations or interactions between site age and substrate precluded categorization of all species. Thirty-eight percent (9/24) of the tree species were successional, a result which contrasts sharply with data from (formerly) continental forest in Panama. Spatial distributions of 33 species revealed 17 species exhibiting clumping or hyperdispersion (i.e., regular spacing) in at least one site. Possible non-anthropogenic mechanisms promoting clumping in the plots were (a) topography (edaphic), (b) gap affiliation, (c) inefficient or altered patterns of propagule dispersal, and (d) lack of natural seedling predators. Forest structure differed across site type, with stem densities highest in regenerating forest; conversely, regenerating forest had the lowest basal areas. Steep talus forest sequestered the most carbon (344.3 Mg ha 1 ), and secondary forest sustained only 42% of levels found in talus forest (145.5 Mg ha 1 ). Mature forest on non-talus soil sequestered the majority of carbon in mid-sized trees (30‐50 cm dbh). Future assessments of land-use cover and biomass will provide for a complete estimate of the carbon budget of Tutuila. Finally, the results of this study suggest that conservation of the native fauna is essential in retaining the potential for regeneration of native forest after large-scale disturbance.

Tree community diversity of lowland swamp forest in Northeast Costa Rica, and changes associated with controlled selective logging

In the Atlantic lowlands of Northeast Costa Rica, logging occurs in tracts of poorly drained wet forest ('swamp forest'), yet little is known about factors affecting swamp forest diversity or the potential for biodiversity retention during harvest. This paper quantitatively describes the species composition and diversity of the swamp forest habitat, and reports the immediate impact of controlled, selective logging on tree community diversity. Pentaclethra macroloba (Leguminosae), Carapa nicaraguensis (Meliaceae) and Pterocarpus officinalis (Leguminosae) accounted for >70% of the primary swamp forest basal area. Nevertheless, 225 species from 53 families with individuals ≥10cm dbh were encountered in 16.4 ha; most species had very low abundances. Gamma diversity is a component of overall swamp forest diversity. Extraction of 49.2m3ha−1 (5.5 trees ha−1) of timber from a 4ha plot reduced species richness by 14, supporting assertions that random mortality during logging can affect the distribution of rare species. However, tree community diversity as measured by rarefaction was not greatly affected by selective logging. Total post-logging stem recruitment over a 3-year period was greater in logged plots than in undisturbed plots; the recruitment of the ruderal species Ochroma lagopus (Bombacaceae) was the most clearly affected by logging. Any localized dominance by this species will be limited in space and time in a carefully managed forest. The results suggest that controlled selective logging can be consistent with biodiversity conservation, and complement protected areas in Northeast Costa Rica.

Relating Tree Physiology to Past and Future Changes in Tropical Rainforest Tree Communities

Predicting future changes in tropical rainforest tree communities requires a good understanding of past changes as well as a knowledge of the physiology, ecology and population biology of extant species. Climate change during the next hundred years will be more similar to climate fluctuations that have occurred in the last few thousand years and of a much smaller magnitude than the extent of climate change experienced during last glaciation or at the Pleistocene–Holocene transition. Unfortunately, the extent to which tropical rainforest tree communities have changed during the last few thousand years has been little investigated. As a consequence we lack the detailed evidence for population and range shifts of individual tropical species resulting from climate change analogous to the evidence available for temperate zone forests. Some evidence suggests that the rate of tropical forest change in the last several thousand years may have been high. If so, then CO2 increases and the likely alterations in temperature, forest turnover rate, rainfall, or severe droughts may drive substantial future forest change. How can we predict or model the effects of climate change on a highly diverse tree community? Explanations for the regulation of tropical tree populations often invoke tree physiology or processes that are subject to physiological regulation such as herbivory, pathology or seed production. In order to incorporate such considerations into climate change models, the physiology of a very diverse tree community must be understood. My work has focused on simplifying this diversity by categorizing the shade-tolerant species into functional physiological groups. Most species and most individual trees are shade-tolerant species, gap-requiring species being relatively uncommon. Additionally, in a regenerating gap most of the individuals are shade-tolerant species that established before gap formation. Despite the fact that the shade-tolerant species are of major ecological importance, their comparative physiology has received little attention. I have found that shade-tolerant species differ substantially in their responses to light flecks, treefall light gaps and drought. Furthermore, among phylogenetically unrelated species, these differences in physiology can be predicted from leaf lifetime. These results provide a general framework for understanding the mechanics of tropical rainforests from a physiological perspective that can be used to model their responses to climate change.

An analysis of urban tree communities using Landsat Thematic Mapper data

Highly diverse tree communities of natural and planted forests are found in distinct microhabitats in urban settings. The purpose of this paper is to examine the possibility of locating and analyzing urban tree communities at a relatively low cost, using the new satellite imagery data collected from the U.S. Landsat Thematic Mapper (TM). Mobile, Alabama, is the study area. A multichannel TM data set of the study area is analyzed using the hierarchical clustering and minimum-distance classification procedures of the Earth Resources Laboratory Applications Software. The data analysis, at one detail level chosen for this study, reveals 23 spectral classes of trees. Ground checking has verified that the 23 spectral classes include 8 distinct tree communities of remnant natural forests and 15, of cultivated residential forests. These tree communities, developed naturally or planted, vary with species composition, age, density, crown closure, and vertical structure. The detailed analysis of urban forests using TM data assists foresters and planners in the modification or maintenance of urban trees suited to local site conditions. It provides a database for achieving a balanced forest structure and composition that will promote neighborhood planning and the health, safety, and welfare of urban residents. The study has also disclosed the potential of TM data in creating or updating economic geographic information systems of tree communities in metropolitan areas to hasten urban forestry management and comparative research.