Tree Species In Forest Community Research Articles

DETERMINATION OF FUNCTIONAL GROUPS OF TREE SPECIES IN AN INSULAR ENVIRONMENT

The Atlantic Forest is the third largest biome in Brazil, but currently, approximately 12.4% of its native vegetation remains. Given its importance and structural complexity, studies that contribute to its conservation appeal have been increasingly requested. In this context, the functional approach has helped improve the understanding of the coexistence patterns of tree species in forest communities. This separation of species into functional groups aims to highlight the functioning of one or more processes of interest. The present study aimed to identify the functional groups, richness, and diversity of the vegetation of Ilha dos Remédios, located in the municipality of Balneário Barra do Sul/SC. The island has an area of approximately 246,013 m² and is 1.5 km from the mainland. To identify the arboreal vegetation, sampling was conducted using the 100 m² plot method. A total of 244 individuals were sampled, belonging to 26 species from 18 families, divided into 3 functional groups through Cluster Analysis. A low diversity of functional groups was recorded, with an overlap of these groups in some ecological attributes, corroborating the trend towards functional redundancy in historically degraded areas such as the study area.

Diversity, Ecology and Phytogeography of Bryophytes across Temperate Forest Communities-Insight from Mt. Papuk (Croatia, SE Europe).

It has been widely documented that the complex structure of forest ecosystems supports considerable bryophyte species and functional diversity. In this study, we assessed the diversity, distribution and ecological and phytogeographical features of bryophytes across a gradient of temperate forest types on Mt. Papuk. This is the largest and highest mountain in the lowland, Pannonian part of Croatia, with high geological diversity and various temperate forests covering 95% of the mountain. According to the predominant tree species (oak vs. beech), geological bedrock (calcareous vs. siliceous) and soil reaction (alkaline vs. acidic), 21 study plots were classified into four distinct forest types. In all, 184 bryophyte species (35 liverworts and 149 mosses) were recorded. Although the forest types investigated did not differ significantly with respect to species richness, each was characterized by a considerable number of diagnostic bryophyte species. According to our results, one of the main ecological factors determining the variability of the forest bryophyte composition was geological bedrock and the associated soil reaction. Basiphilous forests developed on carbonate bedrock harbored more thermophilous and nitrophilous bryophytes and were characterized by southern-temperate and Mediterranean-Atlantic biogeographic elements. In contrast, acidophilous forests growing on silicate bedrock were characterized by wide-boreal and boreo-arctic-montane elements, i.e., bryophytes indicating cooler habitats and nitrogen-deficient soils. Based on the results, we hypothesized that the main latitudinal biogeographic distinction between southern and northern biogeographic elements is driven more by geological substrate than by the main tree species in forest communities. The present study confirmed previous findings that bryophytes are good and specific habitat indicators and show associations with different forest types, which can help to understand the complexity, ecological microconditions and biogeographic characteristics of forest communities.

Identification of Tree Species in Forest Communities at Different Altitudes Based on Multi-Source Aerial Remote Sensing Data

The accurate identification of forest tree species is important for forest resource management and investigation. Using single remote sensing data for tree species identification cannot quantify both vertical and horizontal structural characteristics of tree species, so the classification accuracy is limited. Therefore, this study explores the application value of combining airborne high-resolution multispectral imagery and LiDAR data to classify tree species in study areas of different altitudes. Three study areas with different altitudes in Muyu Town, Shennongjia Forest Area were selected. Based on the object-oriented method for image segmentation, multi-source remote sensing feature extraction was performed. The recursive feature elimination algorithm was used to filter out the feature variables that were optimal for classifying tree species in each altitude study area. Four machine learning algorithms, SVM, KNN, RF, and XGBoost, were combined to classify tree species at each altitude and evaluate the accuracy. The results show that the diversity of tree layers decreased with the altitude in the different study areas. The texture features and height features extracted from LiDAR data responded better to the forest community structure in the different study areas. Coniferous species showed better classification than broad-leaved species within the same study areas. The XGBoost classification algorithm showed the highest accuracy of 87.63% (kappa coefficient of 0.85), 88.24% (kappa coefficient of 0.86), and 84.03% (kappa coefficient of 0.81) for the three altitude study areas, respectively. The combination of multi-source remote sensing numbers with the feature filtering algorithm and the XGBoost algorithm enabled accurate forest tree species classification.

АHТРОПОГЕННАЯ ТРАНСФОРМАЦИЯ ГОРНО-ЛЕСНЫХ ПОЧВ В СЕВЕРО-ВОСТОЧНОЙ ЧАСТИ МАЛОГО КАВКАЗА (НА ПРИМЕРЕ БАССЕЙНА р. БАБАДЖАН)

Our planet needs the rational use of forest resources and forest soils in order to combat erosion and preserve the biosenosis. Soils provide the basis for the growth of trees and woodlands, and are an essential component of forests and forest ecosystems, as they are involved in the regulation of such important processes as the absorption of nutrients, their decomposition and maintenance of water balance. By reducing the risk of soil erosion and the threat of landslides and avalanches, the sustainable use of forest resources greatly contributes to the functioning of the systems responsible for maintaining the planet’s clean water supply, as well as a balanced water cycle. In the soil environment, trees develop root systems and in turn, forest trees and vegetation in general are an important factor in protecting the soil cover. The authors have examined the natural and anthropogenic degradation of brown mountain-forest soils under a beech forest, brown mountain-forest soils under hornbeam and oak forests in the north-eastern part of the Lesser Caucasus in the Babadjan river basin. The erosional relief of the studied region is represented by highly dissected low mountains, middle mountains and mountain basins, which are rather densely indented by mountain rivers. In conditions of such a relief, soils are well developed in dry low mountains and in the humid part of the middle mountains. To clarify the effect of soil properties on the growth and development of tree species in forest communities of the study area, soil sections were laid. The influence at altitudes of 950-1800 m above sea level, the slope of the relief, the exposure of slopes, the composition of the forest cover, the lithological composition of the parent rocks, the physic-chemical composition of the soil and other factors on the intensity of the degradation process in different ecosystems have been studied

Disentangling environmental and spatial effects on phylogenetic structure of angiosperm tree communities in China

Niche-based and neutrality-based theories are two major classes of theories explaining the assembly mechanisms of local communities. Both theories have been frequently used to explain species diversity and composition in local communities but their relative importance remains unclear. Here, we analyzed 57 assemblages of angiosperm trees in 0.1-ha forest plots across China to examine the effects of environmental heterogeneity (relevant to niche-based processes) and spatial contingency (relevant to neutrality-based processes) on phylogenetic structure of angiosperm tree assemblages distributed across a wide range of environment and space. Phylogenetic structure was quantified with six phylogenetic metrics (i.e., phylogenetic diversity, mean pairwise distance, mean nearest taxon distance, and the standardized effect sizes of these three metrics), which emphasize on different depths of evolutionary histories and account for different degrees of species richness effects. Our results showed that the variation in phylogenetic metrics explained independently by environmental variables was on average much greater than that explained independently by spatial structure, and the vast majority of the variation in phylogenetic metrics was explained by spatially structured environmental variables. We conclude that niche-based processes have played a more important role than neutrality-based processes in driving phylogenetic structure of angiosperm tree species in forest communities in China.

Relationship between clade age and temperature for angiosperm tree species in forest communities along an elevational gradient in tropical Asia

Relationship between clade age and temperature for angiosperm tree species in forest communities along an elevational gradient in tropical Asia

Heterogeneity in soil water and light environments and dispersal limitation: what facilitates tree species coexistence in a temperate forest?

In the present study, we analysed the habitat association of tree species in an old-growth temperate forest across all life stages to test theories on the coexistence of tree species in forest communities. An inventory for trees was implemented at a 6-ha plot in Ogawa Forest Reserve for adults, juveniles, saplings and seedlings. Volumetric soil water content (SMC) and light levels were measured in 10-m grids. Relationships between the actual number of stems and environmental variables were determined for 35 major tree species, and the spatial correlations within and among species were analysed. The light level had no statistically significant effect on distribution of saplings and seedlings of any species. In contrast, most species had specific optimal values along the SMC gradient. The optimal values were almost identical in earlier life stages, but were more variable in later life stages among species. However, no effective niche partitioning among the species was apparent even at the adult stage. Furthermore, results of spatial analyses suggest that dispersal limitation was not sufficient to mitigate competition between species. This might result from well-scattered seed distribution via wind and bird dispersal, as well as conspecific density-dependent mortality of seeds and seedlings. Thus, both niche partitioning and dispersal limitation appeared less important for facilitating coexistence of species within this forest than expected in tropical forests. The tree species assembly in this temperate forest might be controlled through a neutral process at the spatial scale tested in this study.

Spatial associations among major tree species in a cool-temperate forest community under heterogeneous topography and canopy conditions

Analysis of the spatial pattern of plants may provide insight into the processes and mechanisms that promote species coexistence and community organization. Using torus-translation tests and point-pattern analyses for a heterogeneous Poisson process, we investigated habitat association and intra- and inter-specific spatial relationships of six major tree species in a cool-temperate forest community. All stems ≥5 cm in diameter at breast height were mapped on a 1.4-ha (100 × 140 m) plot and the topographic conditions (convexity and slope degree) and canopy state were assessed. Our results showed that all six species exhibited habitat associations with topographic and/or canopy conditions except for Magnolia salicifolia. Intra-specific aggregation was found for Acer japonicum, M. salicifolia, and Hamamelis japonica var. obtusata. Community-wide analysis of the inter-specific spatial patterns showed mainly mixed or partially overlapped patterns at a scale of up to 30 m, whereas individual pairwise analyses of inter-specific patterns revealed that Fagus crenata was positively associated with two Acer species and M. salicifolia at a spatial scale of up to 5 m. These results highlight that scale-dependant ecologically important processes, such as species-specific habitat preference, regeneration mode, seed dispersal, facilitation and niche complementarity, may operate simultaneously to shape tree distributional patterns, although their presence/absence as well as relative importance vary among species. Given the complexity of the process and mechanisms promoting species coexistence and community organization, more attention should be given to the effect of spatial scale in analyzing the spatial patterns of tree species in forest communities.

The Determination of Nitrate Reductase Activity of Leaves to the Dominant Species in Forest Community of Northern Aspect of Changbai Mountains

This paper addresses the application of improvement in vivo of traditional method for determination of nitrate reductase (NR) activity of leaves to dominant tree species in forest community of northern aspect of Changbai Mountains. It describes the NR activity of tree species related to the shade-endurance and shows that the intolerance tree species has higher NR activity. The NR of a species is also related to the ecological situation of the sites. Tree species with higher NR activities should be selected for breeding of fast growing and high yield tree species.

Point patterns of tree distribution determined by habitat heterogeneity and dispersal limitation

Understanding processes underlying spatial distribution of tree species is fundamental to studying species coexistence and diversity. This study modeled point patterns of tree distribution, expressed by Cartesian coordinates of individual trees within a mapped forest stand, for the purpose of identifying processes that may generate spatial patterns of tree communities. We used four primary point pattern processes (homogeneous Poisson process, inhomogeneous Poisson process, homogeneous Thomas process, and inhomogeneous Thomas process) to model tree distribution in two stem-mapped forests in Taiwan, Republic of China. These four models simulate spatial processes of habitat association and seed dispersal, allowing us to evaluate the potential contribution of habitat heterogeneity and dispersal limitation to the formation of spatial patterns of tree species. The results showed that the inhomogeneous Thomas process was the best fit model and described most of the species studied, suggesting that spatial patterns of tree species might be formed by the joint effects of habitat associations and dispersal limitation. The homogeneous Thomas process that models the effect of dispersal limitation was the second best model. We also found that the best fit models could be predicted by species attributes, including species abundance and dispersal mode. The significant traits, however, differed between the two study plots and demonstrated site-specific patterns. This study indicated that the interactive operation of niche-based (habitat heterogeneity) and neutral-based (dispersal limitation) may be important in generating spatial patterns of tree species in forest communities.