Composition Of Woody Plant Communities Research Articles

Forest species diversity and community composition in the northern Western Ghats, India

ABSTRACT Background The northern Western Ghats (NWG) – a part of the Western Ghats and Sri Lanka biodiversity hotspot supports tropical forests of conservation priority, due to anthropogenic intensification. Woody species diversity and ecology in NWG is poorly studied, necessitating the knowledge of spatial variability in species and underlying environmental factors, for effective conservation. Aims We described woody plant community composition and related it to climate data across a latitude of 1.4 degrees to obtain information about spatial and environmental variation to support protected area planning. Methods To estimate abundance, importance value index, diversity indices and rank – abundance, we recorded woody species in 144 plots across 12 sites. Elevation, temperature, rainfall, humidity data were related to diversity descriptors in a canonical correspondence analysis. Results We recorded 10,291 trees representing 187 species of 52 families. Divergent geo-climatic factors were related to distinct plant community structures, elevation and humidity being the most influential drivers of plant diversity and density. Numerous rare species were found restricted to environmentally distinct forests. Conclusion The wide-ranging environment and corresponding variations in forest community composition across the narrow latitudinal range of the study area revealed the importance of including such gradients in planning future protected areas in the NWG.

Urbanization drives divergence in functional diversity and composition of woody plant communities in remnant forest patches

Urbanization has a profound impact on the ecological processes and plant diversity of remnant forests. To understand the relationship between urbanization and woody plant communities in remnant forests, we conducted a study in Guiyang, China, where we sampled 120 plots in 15 remnant forest patches along an urbanization gradient. We evaluated the functional diversity of woody plants based on four functional diversity indices and nine functional traits. We compared the functional diversity among different types of woody plants and between interior and edge communities, and analyzed the changes in functional diversity and individual functional traits along the urbanization gradient. Our results indicate that urbanization significantly decreases the functional diversity of woody plant communities. Additionally, urbanization leads to shifts in functional composition, particularly in shrub species, with an increase in leaf N content and a decrease in leaf C content, leaf C/N ratio, seed germination rate and seed mass. These findings suggest that increasing urbanization reduces the values of high resource-conserving traits of woody plants in remnant forests. Therefore, it is crucial to limit additional urban expansion around remnant forest patches to protect the functional diversity and crucial plant species with strong resource-conserving traits.

Linkages between Plant Community Composition and Soil Microbial Diversity in Masson Pine Forests.

Plant species identity influences soil microbial communities directly by host specificity and root exudates, and indirectly by changing soil properties. As a native pioneer species common in early successional communities, Masson pine (Pinus massoniana) forests are widely distributed in subtropical China, and play a key role in improving ecosystem productivity. However, how pine forest composition, especially the dominance of plant functional groups, affects soil microbial diversity remains unclear. Here, we investigated linkages among woody plant composition, soil physicochemical properties, and microbial diversity in forests along a dominance gradient of Masson pine. Soil bacterial and fungal communities were mainly explained by woody plant community composition rather than by woody species alpha diversity, with the dominance of tree (without including shrub) species and ectomycorrhizal woody plant species accounting for more of the variation among microbial communities than pine dominance alone. Structural equation modeling revealed that bacterial diversity was associated with woody plant compositional variation via altered soil physicochemical properties, whereas fungal diversity was directly driven by woody plant composition. Bacterial functional groups involved in carbohydrate and amino acid metabolism were negatively correlated with the availability of soil nitrogen and phosphorus, whereas saprotrophic and pathogenic fungal groups showed negative correlations with the dominance of tree species. These findings indicate strong linkages between woody plant composition than soil microbial diversity; meanwhile, the high proportion of unexplained variability indicates great necessity of further definitive demonstration for better understanding of forest-microbe interactions and associated ecosystem processes.

Changes in phylogenetic structure and species composition of woody plant communities across an elevational gradient in the southern Taihang Mountains, China

Changes in phylogenetic structure and species composition of woody plant communities across an elevational gradient in the southern Taihang Mountains, China

Environmental factors driving the succession and differentiation of ecological strategy spectrum in tropical lowland rain forest

We aimed to determine the environmental driving factors underpinning successional changes in a tropical lowland rain forest in Hainan. Using hectare scale plots, we evaluated woody plant community composition and collected a variety of environmental variables. We found that the ecological strategy spectrum of communities in the four succession stages differentiated along the C-S axis, but no major communities were found in the R strategy group. The spectrum of ecological strategy of different communities is significantly different with succession, among which C strategy group is on the rise, S strategy group is on the decline, and the intermediate (INT) group strategy is on the rise after the first decline. For the C strategy group, population density and canopy openness explain most of the differences. The S strategy group are explained by slope and population density, while the first two explanatory factors of intermediate strategy group differences are slope and soil total potassium content. The change of plant ecological strategy is the result of comprehensive action of biotic factors, topographic factors and soil factors, among which biotic factors play a leading role.

Silky dogwood (Swida amomum) seed dispersal by freshwater turtles.

Effective seed dispersal is essential to the success of plant species. Swida amomum (silky dogwood) has a seed-dispersal syndrome characteristic of autumn-ripening shrubs with fleshy fruits; attached fruits are ingested and defecated by birds, while fallen fruits are consumed by ground-foraging birds and mammals. We documented that fallen fruits of this shrub were consumed by two aquatic turtle species (eastern painted turtle [Chrysemys picta] and red-eared slider [Trachemys scripta]) and that their seeds were defecated. We compared germination success (percentage of seeds germinated) of defecated seeds, seeds collected from a pond surface, and seeds removed from shrubs. While four seed species were identified in fecal samples, seeds of S. amomum were the most frequent (93%) among samples and the most numerous (106 seeds) in any sample. Average proportion of fecal seeds germinated (85.99%) exceeded that of seeds from the pond surface (82.76%) and from shrubs (60.24%), albeit the difference in germination success was insignificant. When analyzed using fecal samples from painted turtles only, the difference in germination success between fecal seeds and those collected from pond or shrub became significant. Our findings represent the first report of S. amomum seeds being dispersed by turtle gut passage and suggest aquatic turtles could be an important part of a secondary seed dispersal process influencing woody plant community composition in temperate wetland ecosystems.

Mixed-Severity Wildfire as a Driver of Vegetation Change in an Arizona Madrean Sky Island System, USA

Fire is a powerful natural disturbance influencing vegetation patterns across landscapes. Recent transitions from mixed-species forests to post-fire shrublands after severe wildfire is an increasingly prevalent phenomenon in pine-oak and conifer forest ecosystems in southwestern North America. However, we know little about how variation in fire severity influences other common forest types in the region. In this study, we evaluated fire-induced changes in woody plant community composition and forest structure in Chiricahua Mountains in southeastern Arizona in the United States that hosts a diverse set of vegetation types. Cluster analysis of the pre-fire vegetation data identified three dominant pre-fire vegetation types including juniper woodland, piñon forest, and pine-oak forest. All vegetation types experienced significant tree mortality across a wide range of size classes and species, from forests to shrublands. The magnitude of change within sample plots varied with fire severity, which was mediated by topography. Significant shifts in dominance away from coniferous obligate seeder trees to resprouting hardwoods and other shrubs occurred across all vegetation types in response to the fire. Regeneration from seed can be episodic, but projected increases in aridity and fire frequency may promote continued dominance by hardwoods and fire- and drought-resistant shrub communities, which is a regional forest management concern as wildfire size and severity continue to increase throughout the southwestern USA.

Annual fires reduce local species richness but do not homogenize the composition of savanna woody species

Savanna woody species evolved with fire. However, the effect of changes in the fire regimes, which tend to increase in the next decades, is not yet fully understood. Here, we tested the effects of increased fire frequency on species richness and the composition of woody plant communities. Specifically, we tested if a high frequency fire management reduces local species richness of communities and homogenizes species composition. We sampled woody plants in 40 sites, distributed in 20 pairs, in Emas National Park (Brazil). Each pair included sites with high fire frequency (firebreaks that are burned annually since 1994) and with natural fire frequency (occurring every 3–5 years). We used a paired t-test to assess effects of the two fire frequency treatments on species richness and permutation tests to compare distance decay in similarity composition and relative abundances. We found that sites with high fire frequency had lower species richness compared to their paired sites subjected to natural fire frequency. However, similarities in species composition among sites with high fire frequency were only slightly higher than among sites subjected to natural fire frequency. The rate of distance decay in similarity was similar on the two treatments. At local scales, the high frequency of fire reduced species richness, an impact that in the long run may be irreversible. However, at broader spatial scales, effects were small as two treatments included similar sets of species. Prescribed fires have the potential to modify the natural dynamics of the woody communities in the savannas we studied. In our study, fire appears to act as a hierarchical filter, selecting species at broader spatial scales and nesting communities at local scales.

Effects of Elk and Bison Herbivory on Narrowleaf Cottonwood

Ungulate browsing influences the structure and composition of woody plant communities, including species composition and biomass production as well as age distribution, recruitment, and mortality. We evaluated effects of elk and bison herbivory on narrowleaf cottonwood (Populus angustifolia) communities in a semiarid ecosystem in southern Colorado. Cottonwoods in this ecosystem have been aged at ≥300 years old and are among the oldest cottonwood trees in North America. We compared browsing intensity and structural and productivity responses of cottonwood to ungulate herbivory. We compared responses in sites with elk and bison, sites with elk but no bison, and sites where both ungulates were excluded. We found that the majority of browsing on cottonwood occurred during summer in this high desert ecosystem. Areas with both elk and bison had higher browse utilization than areas with only elk, but diet data indicated that elk consumed a much greater proportion of cottonwood than bison. Overall, browse utilization observed in this study was low to moderate compared to other studies, and our results may not be representative of sites experiencing intense year-round herbivory. Removal of all ungulate herbivory led to taller and denser cottonwood suckers; however, other environmental factors, in addition to herbivory, still strongly limit cottonwood growth and recruitment in this ecosystem.

Composition of woody plant communities drives macrofungal community composition in three climatic regions

AbstractQuestionsMacrofungi provide important ecosystem functions and economic value. However, their distributive patterns among woody plant communities and the influence of abiotic factors remain poorly understood. We hypothesized that: (a) the community composition and richness of woody plants are significantly positively correlated with macrofungal community composition and species richness; and (b) in addition to plant effects, abiotic factors (geography and climate) contribute significantly to the variability within macrofungal communities.LocationNorthwest (Zhongdian County), west (Baoshan City) and southwest (Xishuangbanna Autonomous Prefecture) Yunnan Province, China.MethodsWe investigated macrofungi, woody plants and abiotic factors at 30 plots across three climate types in Yunnan Province, China. We assessed the distributive patterns and driving factors of macrofungal communities in temperate, subtropical and tropical regions.ResultsMacrofungal species richness did not significantly increase alongside woody plant species richness, while dissimilarities in macrofungal community compositions across the three climatic regions correlated significantly with woody plant communities, elevation, mean annual precipitation, mean annual temperature, longitude and latitude. Variation partitioning analysis indicated that variations in macrofungal community compositions were explicable by woody plant community composition, as well as by spatial and climatic factors. The Mantel test further revealed that woody plant functional groups shaped macrofungal functional groups. These results indicate that the distribution of macrofungi at the regional scale is mainly affected by woody plant communities, followed by spatial and climatic factors in the three climatic regions.ConclusionsWe concluded that dominant woody plant species could be used as indicators of macrofungal community compositions. Accordingly, applying knowledge on the dominant woody plant communities into forest management schemes could be an effective strategy for supporting macrofungal conservation.

Conservation value of moist evergreen Afromontane forest sites with different management and history in southwestern Ethiopia

Tropical forest ecosystems harbor high biodiversity, but they have suffered from ongoing human-induced degradation. We investigated the conservation value of moist evergreen Afromontane forest sites across gradients of site-level disturbance, landscape context and forest history in southwestern Ethiopia. We surveyed woody plants at 108 randomly selected sites and grouped them into forest specialist, pioneer, and generalist species. First, we investigated if coffee dominance, current distance from the forest edge, forest history, heat load and altitude structured the variation in species composition using constrained correspondence analysis. Second, we modelled species richness in response to the same explanatory variables. Our findings show that woody plant community composition was significantly structured by altitude, forest history, coffee dominance and current distance from forest edge. Specifically, (1) total species richness and forest specialist species richness were affected by coffee management intensity; (2) forest specialist species richness increased, while pioneer species decreased with increasing distance from the forest edge; and (3) forest specialist species richness was lower in secondary forest compared to in primary forest. These findings show that coffee management intensity, landscape context and forest history in combination influence local and landscape level biodiversity. We suggest conservation strategies that foster the maintenance of large undisturbed forest sites and that prioritize local species in managed and regenerating forests. Creation of a biosphere reserve and shade coffee certification could be useful to benefit both effective conservation and people's livelihoods.

The composition and complexity of the woody and succulent components of Albany thicket with and without elephants

African elephants (Loxodonta africana) are capable of visibly altering the structure of vegetation through their browsing habits, and such alteration of habitat may be magnified when the broader movements of elephants are restricted by fences. I assessed the structure and composition of the woody and succulent components of Albany thicket vegetation at 10 fenced sites in the Eastern Cape Province, South Africa – five with elephants present, paired with five where elephants were absent. Contrary to expectations, woody and succulent thicket vegetation was structurally similar across the 10 sites, despite the vegetation at the non-elephant sites being slightly taller, denser and more complex than the sites with elephants. Woody plant community composition was also similar across the 10 sites and elephant-induced damage to woody and succulent plants was generally low. Combined, these findings support the idea that at least the woody component of thicket vegetation is generally resilient to the browsing effects of indigenous browsers such as elephants. However, it is also possible that Albany thicket vegetation at the five elephant sites may not have been exposed to elephants for long enough for elephant browsing effects to manifest. Thus, I recommend continued monitoring of elephant browsing in fenced reserves within the Thicket Biome to establish how overall vegetation structure and composition may change over time, and with increases in elephant densities.

Effects of topoclimatic complexity on the composition of woody plant communities.

Topography can create substantial environmental variation at fine spatial scales. Shaped by slope, aspect, hill-position and elevation, topoclimate heterogeneity may increase ecological diversity, and act as a spatial buffer for vegetation responding to climate change. Strong links have been observed between climate heterogeneity and species diversity at broader scales, but the importance of topoclimate for woody vegetation across small spatial extents merits closer examination. We established woody vegetation monitoring plots in mixed evergreen-deciduous woodlands that spanned topoclimate gradients of a topographically heterogeneous landscape in northern California. We investigated the association between the structure of adult and regenerating size classes of woody vegetation and multidimensional topoclimate at a fine scale. We found a significant effect of topoclimate on both single-species distributions and community composition. Effects of topoclimate were evident in the regenerating size class for all dominant species (four Quercus spp., Umbellularia californica and Pseudotsuga menziesii) but only in two dominant species (Quercus agrifolia and Quercus garryana) for the adult size class. Adult abundance was correlated with water balance parameters (e.g. climatic water deficit) and recruit abundance was correlated with an interaction between the topoclimate parameters and conspecific adult abundance (likely reflecting local seed dispersal). However, in all cases, the topoclimate signal was weak. The magnitude of environmental variation across our study site may be small relative to the tolerance of long-lived woody species. Dispersal limitations, management practices and patchy disturbance regimes also may interact with topoclimate, weakening its influence on woody vegetation distributions. Our study supports the biological relevance of multidimensional topoclimate for mixed woodland communities, but highlights that this relationship might be mediated by interacting factors at local scales.

Effects of Browsing by Captive Elk (Cervus canadensis) on a Midwestern Woody Plant Community

Abstract Elk (Cervus canadensis) can significantly alter plant community composition and reduce plant biodiversity, mass, seedling numbers and sapling growth. Yet, few studies have examined the interactions of reintroduced elk with woody plant communities in eastern North America. To test the hypothesis that elk herbivory would reduce woody plant diversity and recruitment and also change woody plant community composition when compared to deer, we evaluated herbivory effects of a captive elk herd and a free-roaming white-tailed deer (Odocoileus virginianus) population in Land Between the Lakes National Recreation Area in western Kentucky. Elk and deer herbivory did not differ in their effects upon overall woody plant diversity. However, elk browsing significantly altered woody plant community composition (F1,15 = 2.27, P = 0.005), reduced stem heights of Quercus and Cornus genera (Ps < 0.036) and reduced frequencies of Quercus, Nyssa, and Sassafras (Ps < 0.045) when compared to deer. Our results sugges...

Influence of microclimate and species interactions on the composition of plant and invertebrate communities in alpine northern Norway

We assessed the effects of both biotic processes and abiotic factors on the community composition of vascular plant species and invertebrates at a site in northern Norway. Plant species were assigned to functional (woody versus herbaceous) and biogeographic (boreal versus alpine) groups. Invertebrate species were classified as either herbivore or predator. When species interactions and effects of the abiotic environment were partitioned, boreal species appeared to influence the distribution of alpine species and woody species the distribution of herbaceous species. Analysis of partial correlations indicated that facilitation was the dominant mode of interaction between the two pairs of plant groups. Among abiotic factors, the thermal environment probably influenced all components of the plant and invertebrate communities, except for predatory invertebrates, and wind appeared important in determining the composition of woody and alpine components of the plant community but not the herbaceous component. The composition of the boreal component of the plant community apparently influenced the composition of all invertebrate communities, except for predatory invertebrates. The composition of the woody component of the plant community influenced the composition of both herbivore and predator communities. The alpine plant-community composition influenced predatory invertebrate community composition. Woody plant community composition influenced the composition of both herbivore and predator communities. Our analytic approach, based on two kinds of structural equation models (d-separation and path analysis), provides a useful method for identifying the biotic as well as abiotic factors that influence community structure.

Effects of prescribed fire on the composition of woody plant communities in southeastern Texas

Abstract. The response to prescribed burning of plant communities ranging from dry to wet habitats was monitored using permanent plots sampled from 1989 to 1993. Temporal controls for fire effects were provided by matched sets of plots protected from fire by newly constructed fire breaks. Changes in species composition were studied by ordination of strata of trees (&gt; 5 cm DBH), small trees (2–5 cm DBH), large saplings (1–2 cm DBH), and small saplings and seedlings (50–140 cm tall). Results show that changes occurred largely in the small tree stratum, in which xeric species increased in importance. Although there were changes in sapling and seedling strata, no clear direction of change was recognized. Fire had little effect on the tree stratum.Of the seven community types under study, three types, sandhill, upland pine, and upperslope pine‐oak, were most strongly affected, as indicated by post‐fire change in positions of samples representing these communities in ordination space and reduction in understory species abundance. Samples representing the other four mesic and wet communities showed little or no change in their positions.These short‐term results indicate that changes in vegetation resulting from fire were small and were mostly restricted to the dry types in which possible compositional change is expected to occur. This differential effect of fire suggests that the influence of fire is secondary to that of topographical and soil gradients in determining vegetation pattern under current fire regimes. Fire seems to reinforce an overall vegetation gradient controlled by soil in southeastern Texas.

Chamaecyparis thyoides Wetlands and Suburbanization: Effects on Hydrology, Water Quality and Plant Community Composition

(1) Atlantic white cedar (Chamaecyparis thyoides) wetlands in the New Jersey Pinelands were studied along a gradient of suburban development defined by increasingly intrusive road and house construction close to the site. Water table level, water chemistry, plant species composition and community structure were recorded to assess the effects of increasing levels of upland disturbance on the adjacent wetlands. (2) Some increases in nitrogen, phosphorus, and chloride occurred in both surface and groundwater within wetlands beside septic system drain fields. Much larger increases in these parameters, plus increases in heavy metal concentrations, occurred in sites receiving both septic tank drainage and road run-off. (3) Hydrology was only affected by the presence of dams on the streams traversing the wetlands, and by ditches dug in association with stormwater sewer outfalls. (4) With increasing levels of suburban disturbance, there was an increasing loss of indigenous herbaceous species and an increasing incursion of upland and exotic species. Ground cover by Sphagnum spp. and cedar seedling densities all declined with increasing suburban development. Woody plant community composition and structure showed little change over the gradient. Changes in water quality were more important in determining changes in community composition and structure than were changes in hydrology. (5) The changes in species composition associated with changes in water quality support the theory that species-richness follows an optimization curve with respect to nutritional quality of the wetland. (6) The results suggest that the maximum buffer width provided for by law be required for all upland development adjacent to white cedar wetlands.