Environmental drivers shaping plant functional trait diversity in tropical forests of Bangladesh

The complex stratification of tropical forests is a key feature that directly contributes to high aboveground biomass (AGB) and species diversity. This study aimed to explore the vertical patterns of AGB and tree species diversity in the tropical forest of Pasoh Forest Reserve, Malaysia. To achieve this goal, we used a combination of field surveys and drone technology to gather data on species diversity, tree height (H), and tree diameter at breast height (D). As all trees in the 6 ha plot were tagged and identified, we used the data to classify the taxonomy and calculate species diversity indices. We used unmanned aerial vehicle-based structure-from-motion photogrammetry to develop a Digital Canopy Height Model to accurately estimate H. The collected data and previous datasets were then used to develop Bayesian height–diameter (HD) models that incorporate taxonomic effects into conventional allometric and statistical models. The best models were selected based on their performance in cross-validation and then used to estimate AGB per tree and the total AGB in the plot. Results showed that taxonomic effects at the family and genus level improved the HD models and consequent AGB estimates. The AGB was the highest in the higher layers of the forest, and AGB was largely contributed by larger trees, especially specific families such as Dipterocarpaceae, Euphorbiaceae, and Fabaceae. In contrast, species diversity was the highest in the lower layers, whereas functional diversity was the highest in the middle layers. These contrasting patterns of AGB and species diversity indicate different roles of forest stratification and layer-specific mechanisms in maintaining species diversity. This study highlights the importance of considering taxonomic effects when estimating AGB and species diversity in tropical forests. These findings underscore the need for a more comprehensive understanding of the complex stratification of tropical forests and its impact on the forest ecosystem.

Over the past three decades, there has been a concerted effort to study the long‐term dynamics of tropical forests throughout the world. Data regarding temporal trends in species diversity, species composition, and species‐specific demographic rates have now been amassed. Such data can be utilized to test predictions regarding the roles the environment and demographic stochasticity play in driving forest dynamics. These analyses could be further refined by quantifying the temporal trends in the functional composition and diversity in tropical forests. For example, we have only a handful of studies that quantify directional shifts in the functional composition in tropical forests in response to global change drivers. The present study uses data from three censuses spanning 30 yr in a Neotropical dry forest dynamics plot to provide novel insights into how the functional diversity and composition of a tropical forest has changed through time. Specifically, here we aim to (1) quantify population dynamics and compare it to that expected from environmental or demographic variance; (2) quantify long‐term trends in species richness and functional diversity; (3) test whether there have been directional changes in the functional composition of the forest though time and the population changes that are responsible for these changes; and (4) place these long‐term results into the context of the successional and climatic history of the forest.

Arable field margins are valuable habitats providing a wide range of ecosystem services in rural landscapes. Agricultural intensification in recent decades has been a major cause of decline in plant diversity in these habitats. However, the concomitant effects on plant functional diversity are less documented, particularly in Mediterranean areas. In this paper, we analyzed the effect of margin width and surrounding landscape (cover and diversity of land use and field size), used as proxies for management intensity at local and landscape scales, on plant species richness, functional diversity and functional trait values in margins of winter cereal fields in southern Spain. Five functional traits were selected: life form, growth form, seed mass, seed dispersal mode and pollination type. RLQ and fourth-corner analyses were used to link functional traits and landscape variables. A total of 306 plant species were recorded. Species richness and functional diversity were positively related to margin width but showed no response to landscape variables. Functional trait values were affected neither by the local nor landscape variables. Our results suggest that increasing the margin width of conventionally managed cereal fields would enhance both taxonomic and functional diversity of margin plant assemblages, and thus the services they provide to the agro-ecosystem.

Identifying soil characteristics associated with the plant’s resource use and acquisition strategy at different scales could be a crucial step to understanding community assembly and plant strategy. There is an increasing trend that plant functional properties can be an important driver of ecosystem functioning. However, major knowledge gaps exist about how soil abiotic properties, shape species diversity, above-ground biomass (AGB) and plant functional diversity in the Bawangling tropical forest (TCF) of Hainan island. Hence we hypothesized that plant functional traits and above-ground biomass would be strongly associated with soil abiotic factors given their direct relationship to soil resource acquisition and use. Here, we used 12 plant functional traits (FTs), above-ground biomass (AGB), and five soil nutrients in the Bawangling tropical cloud forest of Hainan Island by using a polynomial regression model and multivariate correlations to show relationship and identify how plants allocate their limited resources to adapt to their surroundings. Various phytosociological attributes were assessed and an Importance Value Index (IVI) value was calculated for each species to determine the dominant species. More than half of the total variations could be attributed to interspecific variations in H, DBH, LA, LMA, and LDW. From a taxonomic perspective; we found that species-level variance was more significant for plant functional traits and soil nutrients like TN, AP, TP, and OM. On the other hand, variation in specific stem density (SSD), leaf thickness (LT), leaf phosphorus (LP) and leaf soluble sugar (LS) was an exception for these tendencies. Among soil nutrients, soil nitrogen and phosphorus significantly impact the species and functional traits. Furthermore, the soil AN and TP we also found to have a comparatively strong positive relationship with above-ground biomass (AGB) as compared with other soil nutrients. The morpho-physiological functional traits showed a trade-off between conservative and acquisitive resource usage. These variations suggested that the relationships of functional traits, AGB, and species with soil nutrients mainly AN and TP in tropical cloud forests can directly affect the growth, reproduction, and survival of the species and are beneficial for the species co-existence and maintenance of biodiversity.

Invasive alien species can affect plant taxonomic and functional diversity. Multiple invasive alien species can co-invade the same plant community. However, the effects of such co-invasion on plant taxonomic and functional diversity are currently unclear. Our study aimed to estimate the effects of co-invasion by three Asteraceae invasive alien species (i.e., Conyza canadensis (L.) Cronquist, Conyza sumatrensis (S.F. Blake) Pruski and G. Sancho, and Solidago canadensis L.) on plant taxonomic and functional diversity in herbaceous ruderal communities in southern Jiangsu, China. The effects of these three invasive alien species under seven invasion combinations (including invasion by one invasive alien species, co-invasion by two invasive alien species, and co-invasion by these three invasive alien species) on plant taxonomic and functional diversity were investigated in a comparative field study of herbaceous ruderal communities. Niche differentiation mediated the functional divergence between these three invasive alien species and natives under all invasion combinations. These three invasive alien species significantly increased plant taxonomic diversity (especially plant diversity and richness) and plant functional diversity (especially Rao's quadratic entropies) under all invasion combinations. The relative abundance of invasive alien species was significantly positively associated with plant functional diversity (especially community-weighted mean trait values and Rao's quadratic entropy). The number of invasive alien species was significantly positively associated with plant taxonomic diversity (especially plant diversity and richness) and plant functional diversity (especially Rao's quadratic entropies). Thus, co-invasion by these three invasive alien species may synergistically increase plant taxonomic diversity (especially plant diversity and richness) and functional diversity (especially Rao's quadratic entropies).

PDF HTML阅读 XML下载 导出引用 引用提醒 坡向因子对黄土高原草地群落功能多样性的影响 DOI: 10.5846/stxb201505010900 作者: 作者单位: 陕西师范大学生命科学学院,陕西师范大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 陕西师范大学中央高校基本科研业务费（GK201503044） Effect of slope aspect on the functional diversity of grass communities in the Loess Plateau Author: Affiliation: Shaanxi Normal University, College of Life Sciences,Shaanxi Normal University, College of Life Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究群落水平上的植物功能性状特征及功能多样性随坡向的变化规律，对认识不同坡向上的植物群落形成过程具有重要意义。以黄土高原不同坡向上的自然草地群落为研究对象，比较研究了植物功能性状（株高和比叶面积）和功能多样性测度指标（功能丰富度、功能均匀度和功能离散度）随坡向的变化规律。研究结果显示：（1）阴坡的株高和比叶面积显著高于其他坡向；（2）一元性状的功能丰富度在不同坡向间均无显著差异；阴坡和半阴坡的多元性状功能丰富度显著高于阳坡；（3）阴坡的株高功能均匀度显著高于半阳坡，而比叶面积功能均匀度在各坡向的差异并不显著；多元性状功能均匀度在不同坡向差异显著，阴坡最高，半阳坡最低；（4）阴坡和半阴坡的株高功能离散度显著高于阳坡和半阳坡，而半阴坡的比叶面积功能离散度显著高于阳坡；半阴坡的多元性状功能离散度Rao指数显著高于阳坡。研究结果暗示了，在阴坡和半阴坡上，植物对群落内的生态位空间和资源利用更充分，种间竞争强度较低，不同物种之间生态位高度分化；而在阳坡和半阳坡上，由于水分等条件的限制植物可占据的生态位空间有限，导致其对占据的生态位空间使用不足，物种间资源竞争较强烈。在群落水平上，研究地区的植物功能性状及功能多样性随坡向的规律性变化，反映了黄土高原植被群落构建过程中坡向因子对功能性状的筛选效应。该研究结果对该区的植被恢复重建的物种选择及植被布局规划具有重要实践意义。 Abstract:Functional diversity of a plant community, which is based on plant traits, has been proposed as a key component predicting ecosystem function. Knowledge about how plant functional traits and functional diversity change along with the different slope aspects at the community level is important for understanding the formation of plant communities under distinct slope aspects. However, to date, previous studies on plant communities in sunny and cloudy slope environments have mainly been descriptive. To our knowledge, no research has dealt with the relationship between the slope aspect and community assembly based on plant functional diversity (i.e., functional richness, evenness and divergence). In this study, we aimed to uncover the relationship between slope aspects and plant functional traits. Three sampling transects (1 m × 5 m) were established on each of four sites facing north, south, east, or west, in Malan Mountain, Loess Plateau. Each of the sampling transects were evenly divided into fifteen 1 m × 1 m plots, and a plot survey was conducted. We measured plant height (H) and specific leaf area (SLA), and then calculated three types of functional diversity indices (i.e., functional richness, evenness, and divergence), which included three one-dimensional indices based on single traits (i.e., FRci, FRO, FDvar) and three multi-dimensional indices based on two traits (i.e., FRci, FEve, FDQ). A comparison of the changing pattern of plant functional traits and the three types of functional diversity was conducted among the four slope aspects (the cloudy, sunny, semi-cloudy, and semi-sunny slope). Our results indicated that: (1) the value of H and SLA on the cloudy slope was greater than the others; (2) there was no significant difference among the four slope aspects in one-dimensional functional richness indices of H and SLA, while the multi- dimensional functional richness indices of plants on the cloudy slope and the semi-cloudy slope were greater than those of the plants on the sunny slope; (3) on the cloudy slope, the one-dimensional functional evenness of H was significantly greater compared to those on the semi-sunny slope, while that of SLA was not significantly influenced by the slope aspect; the multi-dimensional functional evenness indices of plants on the cloudy slope was greater than those of the plants on semi-sunny slope; (4) the one-dimensional functional divergence of H on the cloudy and semi-cloudy slope were significantly greater than those on the semi-sunny and sunny slope, while that of SLA on the semi-cloudy slope was significantly greater than those on the sunny slope; the multi-dimensional functional divergence index and Rao's quadratic entropy of plants was significantly greater on the semi-cloudy slope compared with those on the sunny slope. Our results indicated that for plant traits, more niche space was occupied, more resources were sufficiently exploited, lower competition intensity occured, and a high level of niche differentiation existed on the cloudy and semi-cloudy slopes. By contrast, because of the limitation of all kinds of soil conditions and environmental factors, plant traits occupied less niche space on the sunny and semi-sunny slope, resources were exploited less sufficiently, and competition for resources tended to be stronger. At the community-level, the changing pattern of plant functional traits and functional diversity along the four different slope aspects suggests the existence of an environmental fitter effect on functional traits under the process of community assembly in the Loess region. These findings would have significant practical implications for species selection and vegetation rehabilitation layout planning in the hilly area of the Loess Plateau. 参考文献 相似文献 引证文献

Plant diversity is known to influence the abundance and diversity of belowground biota; however, patterns are not well predictable and there is still much unknown about the driving mechanisms. We analyzed changes in soil nematode community composition as affected by long‐term manipulations of plant species and functional group diversity in a field experiment with plant species diversity controlled by sowing a range of 1–60 species mixtures and controlling non‐sown species by hand weeding. Nematode communities contain a variety of species feeding on bacteria, fungi, plants, invertebrates, while some are omnivorous. We analyzed responses of nematode abundance and diversity to plant species and functional diversity, and used structural equation modeling (SEM) to explore the possible mechanisms underlying the observed patterns. The abundance of individuals of all nematode feeding types, except for predatory nematodes, increased with both plant species and plant functional group diversity. The abundance of microbial‐feeding nematodes was related positively to aboveground plant community biomass, whereas abundance of plant‐feeding nematodes was related positively to shoot C:N ratio. The abundance of predatory nematodes, in turn, was positively related to numbers of plant‐feeding nematodes, but not to the abundance of microbial feeders. Interestingly, the numbers of plant‐feeding nematodes per unit root mass were lowest in the high‐diversity plant communities, pointing at reduced exposure to belowground herbivores when plants grow in species‐diverse communities. Taxon richness of plant‐feeding and microbial‐feeding nematodes increased with plant species and plant functional group diversity. Increasing plant functional group diversity also enhanced taxon richness of predatory nematodes. The SEM suggests that bottom‐up control effects of plant species and plant functional group diversity on abundance of nematodes in the various feeding types predominantly involve mechanistic linkages related to plant quality instead of plant quantity; especially, C:N ratios of the shoot tissues, and/or effects of plants on the soil habitat, rather than shoot quantity explained nematode abundance. Although aboveground plant properties may only partly serve as a proxy for belowground resource quality and quantity, our results encourage further studies on nematode responses to variations in plant species and plant functional diversity in relation to both quantity and quality of the belowground resources.

We evaluated trained listener—based acoustic sampling as a reliable and non-invasive method for rapid assessment of ensiferan species diversity in tropical evergreen forests. This was done by evaluating the reliability of identification of species and numbers of calling individuals using psychoacoustic experiments in the laboratory and by comparing psychoacoustic sampling in the field with ambient noise recordings made at the same time. The reliability of correct species identification by the trained listener was 100 % for 16 out of 20 species tested in the laboratory. The reliability of identifying the numbers of individuals correctly was 100% for 13 out of 20 species. The human listener performed slightly better than the instrument in detecting low frequency and broadband calls in the field, whereas the recorder detected high frequency calls with greater probability. To address the problem of pseudoreplication during spot sampling in the field, we monitored the movement of calling individuals using focal animal sampling. The average distance moved by calling individuals for 17 out of 20 species was less than 1.5 m in half an hour. We suggest that trained listener—based sampling is preferable for crickets and low frequency katydids, whereas broadband recorders are preferable for katydid species with high frequency calls for accurate estimation of ensiferan species richness and relative abundance in an area.

Light gap disturbances have been postulated to play a major role in maintaining tree diversity in species-rich tropical forests. This hypothesis was tested in more than 1200 gaps in a tropical forest in Panama over a 13-year period. Gaps increased seedling establishment and sapling densities, but this effect was nonspecific and broad-spectrum, and species richness per stem was identical in gaps and in nongap control sites. Spatial and temporal variation in the gap disturbance regime did not explain variation in species richness. The species composition of gaps was unpredictable even for pioneer tree species. Strong recruitment limitation appears to decouple the gap disturbance regime from control of tree diversity in this tropical forest.

The mutual interdependence of plants and arbuscular mycorrhizal fungi (AMF) is important in carbon and mineral nutrient exchange. However, an understanding of how AMF community assemblies vary in different forests and the underlying factors regulating AMF diversity in native tropical forests is largely unknown. We explored the AMF community assembly and the underlying factors regulating AMF diversity in a young (YF) and an old-growth forest (OF) in a tropical area. The results showed that a total of 53 AMF phylogroups (virtual taxa, VTs) were detected, 38±1 in the OF and 34±1 in the YF through high-throughput sequencing of 18S rDNA, and AMF community composition was significantly different between the two forests. A structural equation model showed that the forest traits indirectly influenced AMF diversity via the plant community, soil properties and microbes, which explained 44.2% of the total observed variation in AMF diversity. Plant diversity and biomass were the strongest predictors of AMF diversity, indicating that AMF diversity was dominantly regulated by biotic factors at our study sites. Our study indicated that forest community traits have a predictable effect on the AMF community; plant community traits and soil properties are particularly important for determining AMF diversity in tropical forests.

Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur sequentially or simultaneously in tropical natural forests. Understanding coexistence and competition mechanisms of tree species requires knowledge of interactions within and between species. However, many conservation efforts and strategies failed due to inability to identify and maintain functional coexistence mechanisms among tree species in the forest. Also, most trees died because of pressure on their habitats and not because of limiting growth resources. Hence, species identity, minimum distance and size of the neighbouring trees which are responsible for coexistence of competing trees in most tropical forests have not been explicitly reviewed. Therefore, this review evaluated some of the density dependent mechanisms for coexistence of tree species alpha diversity in tropical forests. Many interactive mechanisms are responsible for coexistence tree species in tropical forests. Inter- and intra-specific competitions are the most significant and both facilitate positive and negative density dependence. Therefore, switching from negative to positive density dependence may occur in some situations. Positive and negative density effects regulate species abundance and coexistence through conspecific and heterospecific structures. Aggregates of conspecific and heterospecific neighbours constitute forest spatial structure. Negative density interactions are mutually exclusive and basically ranged from effect of species identity of neighbours, distance to neighbours and tree size of the neighbours to reference trees in the community structures. Some mechanisms shorten distances for heterospecific than conspecific interactions. Conspecific structures improved survival and growth of rare tree species. Interactive mechanisms in tree community and population structures facilitate species diversity and size inequality, respectively.

Increasing attention has recently been focused on the linkages between plant functional traits and ecosystem functioning. A comprehensive understanding of these linkages can facilitate to address the eco- logical consequences of plant species loss induced by human activities and climate change, and provide the- oretical support for ecological restoration and ecosystem management. In recent twenty years, the evidence of strong correlations between plant functional traits and changes in ecosystem processes is growing. More importantly, ecosystem functioning can be predicted more precisely, using plant functional trait diversity (i.e., functional diversity) than species diversity. In this paper, we first defined plant functional traits and their im- portant roles in determining ecosystem processes. Then, we review recent advances in the relationships be- tween ecosystem functions and plant functional traits and their diversity. Finally, we propose several impor- tant future research directions, including (1) exploration of the relationships between aboveground and belowground plant traits and their roles in determining ecosystem functioning, (2) incorporation of the im- pacts of consumer and global environmental change into the correlation between plant functional traits and ecosystem functioning, (3) effects of functional diversity on ecosystem multifunctionality, and (4) examina- tion of the functional diversity-ecosystem functioning relationship at different temporal and spatial scales.

Habitat loss and fragmentation result in significant landscape changes that ultimately affect plant diversity and add uncertainty to how natural areas will respond to future global change. This uncertainty is important given that the loss of biodiversity often includes losing key ecosystem functions. Few studies have explored the effects of landscape changes on plant functional diversity and evidence so far has shown far more pervasive effects than previously reported by species richness and composition studies. Here we present a review on the impact of habitat loss and fragmentation on (1) individual functional traits-related to persistence, dispersal and establishment-and (2) functional diversity. We also discuss current knowledge gaps and propose ways forward. From the literature review we found that studies have largely focused on dispersal traits, strongly impacted by habitat loss and fragmentation, while traits related to persistence were the least studied. Furthermore, most studies did not distinguish habitat loss from spatial fragmentation and were conducted at the plot or fragment-level, which taken together limits the ability to generalize the scale-dependency of landscape changes on plant functional diversity. For future work, we recommend (1) clearly distinguishing the effects of habitat loss from those of fragmentation, and (2) recognizing the scale-dependency of predicted responses when functional diversity varies in time and space. We conclude that a clear understanding of the effects of habitat loss and fragmentation on functional diversity will improve predictions of the resiliency and resistance of plant communities to varying scales of disturbance.

Plant-pollinator coextinctions are likely to become more frequent as habitat alteration and climate change continue to threaten pollinators. The consequences of the resulting collapse of plant communities will depend partly on how quickly plant functional and phylogenetic diversity decline following pollinator extinctions. We investigated the functional and phylogenetic consequences of pollinator extinctions by simulating coextinctions in seven plant-pollinator networks coupled with independent data on plant phylogeny and functional traits. Declines in plant functional diversity were slower than expected under a scenario of random extinctions, while phylogenetic diversity often decreased faster than expected by chance. Our results show that plant functional diversity was relatively robust to plant-pollinator coextinctions, despite the underlying rapid loss of evolutionary history. Thus, our study suggests the possibility of uncoupled responses of functional and phylogenetic diversity to species coextinctions, highlighting the importance of considering both dimensions of biodiversity explicitly in ecological studies and when planning for the conservation of species and interactions.

There is increasing awareness that plant community functional properties can be an important driver of ecosystem functioning. However, major knowledge gaps exist about how environmental factors, especially climate and soil abiotic properties, shape plant functional diversity at a regional scale. Furthermore, at those scales the relationships between plant functional and taxonomic diversity have rarely been considered. Here, we used a large database of plant species and functional trait data from 180 temperate grasslands across England, covering a broad range of grassland types, climatic conditions and management intensities, the last having a strong influence on multiple soil variables. Our specific aims were to: (1) identify the dominant environmental factors explaining variation in different facets of plant community functional properties, including community weighted means (CWMs) of functional traits and various multi-trait functional diversity indices; and (2) test whether the relationship between plant functional and taxonomic diversity is mediated by environmental factors at a regional scale. We found that soil abiotic properties (pH and nutrient stocks), but not climate, were the main environmental factors explaining grassland plant functional diversity at a regional scale, with a significant contribution of soil nutrient stoichiometry (N/P ratio). Two indices of plant community functional properties, namely CWMs of specific leaf area and relative growth rate, were explained by interactions between soil pH and N and mean annual precipitation, soil pH soil N and soil N/P ratio. These indices were also negatively related to taxonomic diversity under certain soil abiotic conditions, specifically high soil clay content, pH and N/P. Together, our results indicate that soil abiotic properties rather than climate factors shape plant functional diversity across temperate grassland plant communities at a regional scale. They also suggest that interactions between environmental factors play a significant role in shaping patterns of plant community functional properties. Our findings are of importance for the design and interpretation of future studies using trait and diversity measures as proxies of ecosystem services at regional scales.