Patterns Of Plant Species Diversity Research Articles

Environment and management jointly shape the spatial patterns of plant species diversity of moist grasslands in the mountains of Northeastern Yunnan

Grasslands account for about a quarter of the Earth’s land area and are one of the major terrestrial ecosystems, with significant ecological and economic value. The influence of environmental factors and management types on grassland biodiversity has garnered considerable attention. This study investigated how patterns of species richness are influenced by geographical distance, environmental gradients, and management type in the grasslands of northeastern Yunnan, China. We used structural equation modeling to disentangle the impacts of environment and management on phylogenetic community structure, and partial Mantel tests to estimate the roles of dispersal limitation and environmental filtering on taxonomic and phylogenetic beta diversity of three types of grasslands. Our results show that taxonomic alpha diversity increased in grazed grasslands and decreased in mowed grasslands, compared with protected grasslands. However, the phylogenetic structure of both grazed and mowed grassland communities was clustered, whereas that of protected communities was random. Moreover, both grazing and mowing significantly reduced the taxonomic and phylogenetic beta diversity of grasslands, with the lowest values observed in mowed grasslands. Both taxonomic and phylogenetic beta diversity were dominated by species turnover under different management types. The taxonomic and phylogenetic beta diversities of protected and grazed grasslands were simultaneously affected by environmental filtering and dispersal limitation, with the later playing a stronger role. In addition, mowing and related management measures had a stronger filtering effect on grassland community structure, as reflected by changes in community composition.

Applying regional climatic indicators to study plant diversity patterns in Inner Mongolia

Climate factors have a major influence on biodiversity patterns have often used their mean values to reflect the distribution of different organisms, reducing the faceted information of the study unit to point information, a situation that may affect the accuracy of the study results. However, there has been a lack of systematic and comprehensive discussion on regional climatic indicators and their selection. To address this, we evaluated plant distribution and meteorological data from 88 banners and counties in Inner Mongolia considering five regional climatic indicators that reflect the state of climate factors, heterogeneity, and total resources in each sampling unit. Additionally, we compared and analyzed the advantages of the regional climatic indicators over mean climate indicators to determine the dominant climate factors driving the diversity patterns of plant families, genera, and species. Our results showed that the regional climatic indicators were better than the mean values at reflecting the diversity patterns of plant families and genera. In Inner Mongolia, plant species diversity patterns were mainly influenced by total precipitation and temperature heterogeneity indicators; and concurrently, the correlation between plant family and genus diversity patterns and regional climatic indicators was also higher than the mean values. The extent to which climate explains the diversity patterns of plants increases with decreasing plant taxonomic rank. The results of this study expand the available selection and use of climate indicators in biodiversity research and deepen the understanding of the effects of climate on plant family diversity patterns in arid and semi-arid regions. Therefore, this study provides new perspectives for the rational selection and accurate use of climate or environmental indicators in biodiversity conservation and restoration research.

Species elevational richness gradient and species-area relationship in mountain vegetation of Javakheti highland (Georgia)

Elevational gradients in species richness and species-area relationships are among the most interesting patterns in ecology and biogeography. Both patterns can be characteristic of the same system; however, current knowledge of how these patterns co-exist and how we can disentangle their contributions to biodiversity structure is insufficient. In this article, we tested the effect of elevation and area on the formation of plant species diversity patterns in the forest-free Javakheti Highlands (Georgia). Samples (170 plots) were collected within elevations of 1400-3100 m, and the diversity distribution was examined in relation to altitude, available band area, and sampling. In total, 564 species from 67 families were recorded. Plant species richness was highest at mid-elevations (1900–2200 m), irrespective of area and sampling effort. This was in line with other studies from the Caucasus indicating the generality of plant elevational diversity patterns in the region. Area was not an important predictor of species richness; however, this may be considered a result of insufficient sampling. Our study shows that more research is needed to understand the effect of area on patterns of elevational biodiversity distribution.

Blooming plant species diversity patterns in two adjacent Costa Rican highland ecosystems.

The Costa Rican Paramo is a unique ecosystem with high levels of endemism that is geographically isolated from the Andean Paramos. Paramo ecosystems occur above Montane Forests, below the permanent snow level, and their vegetation differs notably from that of adjacent Montane Forests. We compared the composition and beta diversity of blooming plant species using phenological data from functional plant groups (i.e., insect-visited, bird-visited and insect + bird-visited plants) between a Paramo and a Montane Forest site in Costa Rica and analyzed seasonal changes in blooming plant diversity between the rainy and dry seasons. Species richness was higher in the Montane Forest for all plant categories, except for insect-visited plants, which was higher in the Paramo. Beta diversity and blooming plant composition differed between both ecosystems and seasons. Differences in species richness and beta diversity between Paramo and the adjacent Montane Forest are likely the result of dispersal events that occurred during the last glacial period and subsequent isolation, as climate turned to tropical conditions after the Pleistocene, and to stressful abiotic conditions in the Paramo ecosystem that limit species establishment. Differences in blooming plant composition between both ecosystems and seasons are likely attributed to differential effects of climatic cues triggering the flowering events in each ecosystem, but phylogenetic conservatism cannot be discarded. Analyses of species composition and richness based on flowering phenology data are useful to evaluate potential floral resources for floral visitors (insects and birds) and how these resources change spatially and temporarily in endangered ecosystems such as the Paramo.

Integrals of life: Tracking ecosystem spatial heterogeneity from space through the area under the curve of the parametric Rao’s Q index

Spatio-ecological heterogeneity is strongly linked to many ecological processes and functions such as plant species diversity patterns and change, metapopulation dynamics, and gene flow. Remote sensing is particularly useful for measuring spatial heterogeneity of ecosystems over wide regions with repeated measurements in space and time. Besides, developing free and open source algorithms for ecological modelling from space is vital to allow to prove workflows of analysis reproducible. From this point of view, NASA developed programs like the Surface Biology and Geology (SBG) to support the development of algorithms for exploiting spaceborne remotely sensed data to provide a relatively fast but accurate estimate of ecological properties in vast areas over time. Most of the indices to measure heterogeneity from space are point descriptors : they catch only part of the whole heterogeneity spectrum. Under the SBG umbrella, in this paper we provide a new R function part of the rasterdiv R package which allows to calculate spatio-ecological heterogeneity and its variation over time by considering all its possible facets. The new function was tested on two different case studies, on multi- and hyperspectral images, proving to be an effective tool to measure heterogeneity and detect its changes over time.

三江源区高寒坡地退化植物群落多样性和地上生物量沿海拔梯度的变化特征

PDF HTML阅读 XML下载 导出引用 引用提醒 三江源区高寒坡地退化植物群落多样性和地上生物量沿海拔梯度的变化特征 DOI: 10.5846/stxb202104221056 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 青海省三江源二期工程科研项目(2019-S-1-1);国家自然基金项目(31870433,41671508);第二次青藏高原综合科学考察研究项目(2019QZKK0302) Variation characteristics of plant community diversity and above-ground biomass in alpine degraded slopes along altitude gradients in the headwaters region of three-river on Tibetan plateau Author: Affiliation: Fund Project: This study was supported by the Qinghai Province Sanjiangyuan Phase II Project Scientific Research Project (2019-S-1-1)and the Natural Science Foundation of China (31870433,41671508）and the Second Tibetan Plateau Expedition?(2019QZKK0302) 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:山地生态系统退化对生物多样性和地上生物量,以及相互关系在海拔高度梯度上的格局影响,是认识全球变化和人类干扰引起自然生态系统变化的重要内容。以青藏高原三江源区高寒坡地退化草甸和灌丛为研究对象,探讨退化草甸、灌丛群落物种多样性与地上生物量关系及其沿海拔梯度的变化规律。结果表明:(1)坡地退化的上坡位植被盖度显著大于下坡位(P＜0.05)。坡地退化高寒草甸和高寒灌丛,植物物种多样性沿海拔梯度变化规律一致,均呈现"单峰"分布格局。坡地退化高寒草甸Shannon-wiener指数和Simpson指数二次回归方程解释度达到80%和70%以上(P＜0.05)。(2)坡地退化高寒草甸和高寒灌丛的地上生物量与海拔梯度的变化规律一致,即随海拔升高高寒坡地地上生物量呈先增加后降低的变化趋势。海拔梯度对退化高寒山地地上生物量的解释度达到85%以上(P＜0.05)。(3)物种多样性和地上生物量的关系在两个坡地上表现出一致的规律,呈线性增加的变化趋势。高寒草甸坡地回归方程解释度达到70%,高寒灌丛坡地达到60%(P＜0.05)。坡地退化高寒灌丛植物群落多样性和地上生物量高于高寒草甸植物群落。高寒坡地退化草甸和灌丛植物群落物种多样性以及其与地上生物量之间的关系沿海拔梯度的变化规律一致,海拔梯度造成的环境差异对植物群落物种多样性和地上生物量影响仍较大。该研究对认识三江源区退化山地形成生态学机制,及提出有效的生态恢复措施具有重要参考价值。 Abstract:The impact of alpine ecosystem degradation to biodiversity and aboveground biomass and the two interaction patterns along with the gradient of elevation are critical for understanding the changes in natural ecosystems that induced by global climate change and human disturbance. This research focused on the degraded meadow and shrub of hillside in the headwaters region of three-river on Tibetan plateau and aimed to investigate their relationship between plant species diversity and above-ground biomass along an elevation gradient. We observed that: (1) the vegetation coverage on the upslope of degraded sloping alpine meadows and alpine shrubs was significantly greater than that on the downslope (P＜0.05). Both degraded slopes of alpine meadows and alpine shrubs exhibited a unimodal pattern of plant species diversity over elevation gradients. Furthermore, the interpretation rate of the quadratic regression equations of the Shannon-wiener index and the Simpson index against elevation gradients on alpine meadow slopes achieved more than 80% and 70%, respectively (P＜0.05). (2) The above-ground biomass of degraded sloping alpine meadows and alpine shrubs was consistent with the altitude gradient, that is, the above-ground biomass of alpine meadows and alpine shrubs increased initially then declined with the increase of altitude. Interpretation rate of the quadratic regression equation indicated that the altitude gradient could accounted for more than 85% of the above-ground biomass in degraded alpine meadows and alpine shrubs (P＜0.05). (3) The association between plant species diversity and above-ground biomass exhibited a similar pattern on both alpine meadows and alpine shrubs slopes, which proved to be a linear increasing trend. The interpretation rate of the regression between plant species diversity and above-ground biomass reached more than 70% on alpine meadow slopes and more than 60% on alpine shrub slopes (P＜0.05). Also, the alpine shrubs on degraded slope land had higher plant community diversity and above-ground biomass than alpine meadow plant communities. The species diversity of plants in degraded alpine, alpine meadows, and alpine shrub slopes, as well as their relation with above-ground biomass, was consistent with the pattern of changes along elevation gradients in degraded alpine mountains. These findings suggest that environmental variations induced by altitude gradients continue to have a stronger influence on plant community species diversity and above-ground biomass. This study has important reference value for understanding the formation ecological mechanism of degraded alpine meadow and shrub of hillside in the headwaters region of three-river on Tibetan plateau and putting forward effective ecological restoration measures. 参考文献 相似文献 引证文献

The implication of Fire on Patterns of Plant Species diversity in Northwest uluguru Nature Forest reserve, Tanzania

This study examines the implication of fire on tree species diversity in northwest Uluguru Nature Forest Reserve (UNFR). The study compared tree species diversity between burned and unburned areas, and determined whether burned and unburned areas depicted any variation in stages of succession. Tree species samples were drawn from eighteen stands, and tree species data were ordinate using Nonmetric Multidimensional Scaling (NMS or NMDS) (PC-ORD version 5.10) to describe relationships (similarity and dissimilarities) between tree species, forest succession, and the effect of fire on tree species. Species richness did not vary significantly between burned and unburned plots. However, species composition was high in burned stands, which contributed to a high basal area in burned stands. Unburned stands had low species composition and low basal area. Fire intolerant tree species dominated unburned areas while species in the burned areas were fire adapted. A few species existed in burned and unburned stands. Trees in burned areas are still at a young succession stage while in unburned stands vegetation development has reached a succession stage that the vegetation is stable with hardwood forest formation. A sustainable management plan for the UNFR must base on empirical data on fire regime variation over space and time.

Exotic species drive patterns of plant species diversity in 93 restored tallgrass prairies.

A primary goal of restoration ecology is to understand the factors that generate variability in species diversity and composition among restorations. Plant communities may assemble deterministically toward a common community type, or they may assemble stochastically, ending differently because of weather conditions during establishment, soil legacy effects, or exotic species propagule pressure. To test these alternative hypotheses, we sampled plant communities and soil at 93 randomly selected restored prairies distributed throughout Iowa, USA. Five remnant sites were sampled as a reference. We tested our hypotheses using multiple regressions and investigated the strength of direct and indirect effects on species diversity and richness using structural equation models. The prairie restorations were highly variable in their age, size, diversity, soil characteristics, and how they were managed post-seeding. The strongest predictor of plant species richness and diversity was the degree of invasion, as measured by the abundance of exotic species. Restorations planted with species-rich seed mixes had reduced exotic species abundance, which led indirectly to higher species richness of restorations. Sites with higher organic matter and a more linear shape had a direct positive effect on exotic abundance, which in turn decreased diversity. We found little support for deterministic assembly, and diversity did not increase with the age of planting. Our results indicate that restored prairie communities tend to assemble into states of high or low diversity, driven by invasion from exotic plant species. Management of exotic species is essential for maximizing species diversity in temperate grassland restorations.

Spatial distribution of functional traits of bryophytes along environmental gradients in an Atlantic Forest remnant in north-eastern Brazil

ABSTRACTBackground: Functional trait-based approaches have been used to identify patterns of plant species diversity and composition related to environmental variability/changes. Bryophytes are rapidly affected by perturbations and thus their traits and distribution are expected to show well-defined relationships with environmental variability.Aim: To quantify the impacts of fragmentation on the diversity and structure of epiphytic bryophytes to vertical and horizontal environmental gradients in an Atlantic Forest remnant.Methods: Six functional traits related to water relations and light tolerance were recorded and one of them, the leaf lobule area in liverworts, was selected for morphometric measurements along the gradients analysed. Functional diversity and composition metrics of bryophytes along gradients were compared.Results: Functional diversity changed little along the vertical and horizontal gradients. Conversely, the functional composition of traits changed markedly. Traits related to water storage, such as the presence and area of lobules, and to protection against excess light incidence, such as dark pigments, were more numerous in the canopy and at the fragment edge.Conclusions: Functional composition is more correlated with the vertical and horizontal gradients than functional diversity. The lobule of liverworts stood out as the most relevant trait to explain the adaptive strategies of bryophytes.

Unimodal relationship between three-dimensional soil heterogeneity and plant species diversity in experimental mesocosms

Soil heterogeneity is a primary mechanism explaining plant species diversity. Yet, controlled experiments yield inconsistent soil heterogeneity-diversity (SHD) relationships, ranging from positive, neutral to negative. Here we investigated the SHD relationship by experimentally alternating nutrient-rich and nutrient-poor substrate in three dimensions, creating four levels of soil configurational heterogeneity (cell sizes 0, 12, 24 and 48 cm). Across each mesocosm, a mixture of species with high and low nitrogen requirements was evenly sown. Contrary to earlier experimental findings, this approach yielded a unimodal SHD relationship, peaking at cell size 12 cm. This pattern originated mainly from increased plant diversity of species with high nitrogen requirement. Diversity increases with configurational heterogeneity were not due to greater variation in light niches, and diversity decreases were not due to success of fast growing species. Strikingly, plant density increased monotonically with increasing configurational heterogeneity, indicating that not only more species but also more individuals could coexist. This study provides experimental evidence for unimodal SHD curves in plant communities, which has hitherto only been predicted by models. Our results carry a striking similarity with other unimodal response patterns of plant species diversity, notably in diversity–disturbance and diversity–productivity relationships.

The impacts of geographic, soil and climatic factors on plant diversity, biomass and their relationships of the alpine dry ecosystems: Cases from the Aerjin Mountain Nature Reserve, China

Spatial patterns of plant species diversity, functional diversity, and aboveground plant biomass, and their relationships with environmental factors in the Aerjin Mountain Nature Reserve (AMNR) on the Qinghai-Tibetan Plateau, China were examined in this study. The transect-quadrat sampling method was applied to sample the plant species and functional diversity and the aboveground plant biomass. Statistical package F-diversity v. 2011 was used to calculate the functional diversity index. OriginPro 9.0 drawing software was used to diagram 3-dimensional (longitudinal, latitudinal, and altitudinal) distribution patterns of plant diversity, plant biomass and environmental factors. Correlations among plant biomass, species diversity, functional diversity, and environmental factors were analyzed by using SPSS16.0. The results indicated that alpine steppe was the major vegetation type in high-altitude areas of the southwestern region of the AMNR, alpine wet meadow and alpine steppe were the major vegetation types in low altitude areas of the northeastern region of the AMNR. The vegetation types in mid-altitude areas of the northwestern region and low altitude areas of the southeastern region of the AMNR were primarily alpine desert. Plant species diversity and biomass did not vary significantly along latitudinal, longitudinal, and altitudinal gradients. Plant species diversity was positively correlated with soil total nitrogen, total carbon, organic carbon, and moisture. The functional diversity of the plant community was positively correlated with precipitation and soil moisture. Vegetation biomass was positively correlated with soil total nitrogen, organic carbon, and soil moisture, whereas it was negatively correlated with soil bulk density. Plant species diversity was positively correlated with the functional diversity of the plant community. The integrated effects of geographic factors, soil factors, and meteorological conditions contributed to the spatial heterogeneity of species biodiversity and vegetation biomass of the plant communities in the AMNR, whereas the effects of soil and climatic factors were much stronger than those of geographical factors.

Multiple drivers of plant diversity in coastal dunes: A Mediterranean experience

In light of the global biodiversity loss, syntheses of the available knowledge about drivers of biodiversity are becoming increasingly important. However, despite the high number of studies analyzing patterns of plant species diversity, few attempts have been made to synthesize findings within different ecosystems. In this work, the relative role of a wide set of predictors imputable to three conceptual-methodological domains (abiotic, human-mediated disturbance and landscape domain, hereafter AD, DD and LD) was simultaneously analyzed in 644 random plots distributed along the coastal dunes of Central Italy. Native species richness and focal species cover, both field-recorded, were used as response variables. Predictors pertaining to the three domains were derived from both field surveys and high-resolution remotely sensed imagery (LiDAR and orthophotos). To test how AD, DD and LD affect native species richness and focal species cover, a GLM and a linear model were fitted respectively. The three domains were then ranked according to their relative importance.Although the role of the three domains was always significant, they turned out to unequally contribute to the explanation of native species richness and focal species cover patterns. For Mediterranean coastal dune ecosystems, AD appears to be the key biodiversity driver, followed by DD and LD. Our results suggest that as long as human disturbance is limited, plant diversity will distribute according to species abiotic tolerances, regardless of habitat loss and fragmentation per se. Representing a first effort towards a synthesis of plant diversity drivers in coastal dunes, this work points to the importance, in Mediterranean coastal dune ecosystems, of zonation dynamics, whose occurrence should be addressed as a priority issue by efficient conservations strategies.

Phylogenetic diversity, structure and diversification patterns of endemic plants along the elevational gradient in the Eastern Himalaya

ABSTRACTBackground: Several studies have documented the variation in species diversity patterns along elevational gradients in the Himalaya, but few have reported the evolutionary and biogeographic processes behind these patterns.Aims: To understand whether evolutionary history and phylogeny have any role in structuring plant species communities along an elevational gradient in the Sikkim Himalaya.Methods: We used data on endemic plant species occurrence from primary and secondary sources to construct family-level phylogenetic supertrees for different growth forms with the help of Phylomatic tool of Phylocom. These phylogenetic supertrees were used as a base for testing phylogenetic diversity (PD), niche conservatism, diversification time patterns and phylogenetic structure of various plant growth forms along an elevational gradient.Results: PD was the highest at mid-elevations for all growth forms and PD had a significant positive correlation with endemic species richness. Species at mid-elevations were dominated by the ancestral/primitive taxa. There was phylogenetic clustering at higher elevations and phylogenetic overdispersion at lower and mid-elevations for the majority of the growth forms.Conclusions: Time-for-speciation effect and niche conservatism along elevation (retention of niche-related ancestral elevational distribution over evolutionary time scale by species) together determine plant species diversity patterns in the Himalaya.

Distribution patterns of desert plant diversity and relationship to soil properties in the Heihe River Basin, China

AbstractThe study on the patterns of plant species diversity and the factors influencing these patterns forms the basis of ecology and is fundamental to conservation biology. In this paper, desert plant species diversity and soil properties (nutrient and texture) were investigated along desert region of the Heihe River Basin (HRB) to determine whether soil environmental factors influenced desert plant species diversity. We found a total of 44 shrub and herb species belonging to 40 genera of 17 families. The largest family was the Compositae, accounting for 25.0% of the total. Twenty‐four survey plots were clustered into eight plant community types. The Margalef richness (D), Simpson dominance (C), Pielou evenness (Jsw), and Shannon‐wiener (H) index differed significantly among community types. Redundancy analysis (RDA) revealed a relatively strong relationship between the species diversity and soil environmental factors. The first RDA axis accounted for 80.5% and 81.8% of the variation in soil nutrient and texture properties, respectively, but was not statistically significant. RDA suggested that total phosphorus (TP) and medium sand (0.25–0.5 mm) content were the only two statistically significant factors in the study area. Both classification and ordination resulted in a clear demonstration of the spatial variability of community and soil properties. In general, the distribution pattern of desert plant community was mainly related to soil nutrient and texture properties factors, but the relation was not strong. This study provides insights into desert plant diversity and community conservation of Inland HRB in arid desert ecosystems.

A six-year grazing exclusion changed plant species diversity of a Stipa breviflora desert steppe community, northern China.

Excluding grazers is one of most efficient ways to restore degraded grasslands in desert-steppe communities, but may negatively affect the recovery of plant species diversity. However, diversity differences between grazed and fenced grasslands in desert-steppe are poorly known. In a Stipa breviflora desert steppe community in Northern China, we established six plots to examine spatial patterns of plant species diversity under grazed and fenced conditions, respectively. We addressed three aspects of species diversity: (1) The logistic, exponential and power models were used to describe the species-area curve (SAR). Species richness, abundance and Shannon diversity values change differently with increasing sampling areas inside and outside of the fence. The best fitted model for SAR was the logistic model. Excluding grazers had a significant impact on the shape of SAR. (2) Variograms was applied to examine the spatial characteristics of plant species diversity. We found strong spatial autocorrelations in the diversity variables both inside and outside the fence. After grazing exclusion, the spatial heterogeneity decreased in species richness, increased in abundance and did not change in Shannon diversity. (3) We used variance partitioning to determine the relative contributions of spatial and environmental factors to plant species diversity patterns. Environmental factors explained the largest proportion of variation in species diversity, while spatial factors contributed little. Our results suggest that grazing enclosures decreased species diversity patterns and the spatial pattern of the S. breviflora desert steppe community was predictable.

Spatial pattern of plant species diversity and the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China

Understanding the spatial pattern of plant species diversity and the influencing factors has important implications for the conservation and management of ecosystem biodiversity. The transitional zone between biomes in desert ecosystems, however, has received little attention in that regard. In this study, we conducted a quantitative field survey (including 187 sampling plots) in a 40-km2 study area to determine the spatial pattern of plant species diversity and analyze the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China. A total of 42 plant species belonging to 16 families and 39 genera were recorded. Shrub and semi-shrub species generally represented the major part of the plant communities (covering 90% of the land surface), while annual and perennial herbaceous species occupied a large proportion of the total recorded species (71%). Patrick richness index (R), Shannon-Wiener diversity index (H′), Simpson’s dominance index (D), and Pielou’s evenness index (J) were all moderately spatially variable, and the variability increased with increasing sampling area. The semivariograms for R and H′ were best fitted with Gaussian models while the semivariograms for D and J were best fitted with exponential models. Nugget-to-still ratios indicated a moderate spatial autocorrelation for R, H′, and D while a strong spatial autocorrelation was observed for J. The spatial patterns of R and H′ were closely related to the geographic location within the study area, with lower values near the oasis and higher values near the mountains. However, there was an opposite trend for D. R, H′, and D were significantly correlated with elevation, soil texture, bulk density, saturated hydraulic conductivity, and total porosity (P<0.05). Generally speaking, locations at higher elevations tended to have higher species richness and diversity and the higher elevations were characterized by higher values in sand and gravel contents, bulk density, and saturated hydraulic conductivity and also by lower values in total porosity. Furthermore, spatial variability of plant species diversity was dependent on the sampling area.

Patterns of plant diversity within and among three tropical cloud forest communities in Hainan Island

Aims We explored α and β species diversity, functional diversity and phylogenetic diversity distribution patterns in three tropical cloud forests along environmental gradients in air temperature and precipitation. Methods We sampled plots in three tropical cloud forests which are located in the west (Bawangling, 21 plots, BWL), the southwest (Jianfengling, 12 plots, JFL), and the central of Hainan Island (Limushan, 15 plots, LMS). We collected species data and functional trait data including plant height, specific leaf area, chlorophyll content, leaf thickness and wood density. We assessed the differences withinand among-community species diversity, functional diversity and phylogenetic diversity in these three tropical cloud forests using the Kruskal-Wallis test. Important findings The tropical cloud forests in JFL had the highest species abundance and richness whereas the lowest in LMS. However, the Bray-Curtis and Jaccard dissimilarity coefficients showed the opposite distribution patterns (i.e. the highest in LMS whereas the lowest in BWL). Distinct distribution patterns in species diversity across the three tropical cloud forests may be explained by the air temperature and relative humidity. The functional evenness (FEve) within communities was the highest while functional richness (FRic), Rao’s quadratic ©植物生态学报 Chinese Journal of Plant Ecology 470 植物生态学报 Chinese Journal of Plant Ecology 2016, 40 (5): 469–479 www.plant-ecology.com entropy (RaoQ) and the mean pairwise trait distance among communities were the lowest in JFL, indicating that habitat filtering plays an important role in community assembly. BWL had the highest RaoQ and mean pairwise trait distance among communities, and the lowest FEve, which demonstrated that limiting similarity would be prevalent in forest communities assembled. LMS had the highest FRic within communities and mean nearest trait distance among communities, leading to a limiting similarity influencing forest communities. BWL had the highest Faith phylogenetic diversity (PD) within communities and mean nearest phylogenetic distance among communities, reflecting an overdispersed pattern in phylogenetic structures. LMS had the lowest PD and mean pairwise phylogenetic distance within and among communities, suggesting that a clustered pattern in phylogenetic structures. The mean pairwise phylogenetic distance within and across communities were the highest in JFL while the mean nearest phylogenetic distance within communities was the lowest, indicating that phylogenetic clustering and overdispersion patterns co-occur in this forest. We conclude that both plant species interactions and environmental filtering determine the distribution patterns of plant species diversity, functional diversity and phylogenetic diversity both within and among three tropical cloud forests in Hainan Island.

Mediterranean Biomes: Evolution of Their Vegetation, Floras, and Climate

Mediterranean-type ecosystems (MTEs) are located today in southwestern Australia, the Cape Region of South Africa, the Mediterranean Basin, California, and central Chile. These MTEs possess the highest levels of plant species richness in the world outside of the wet tropics. These ecosystems include a variety of vegetation structures that range from the iconic mediterranean-type shrublands to deciduous and evergreen woodlands, evergreen forests, and herblands and grasslands. Sclerophyll vegetation similar to today's mediterranean-type shrublands was already present on oligotrophic soils in the wet and humid climate of the Cretaceous, with fire-adapted Paleogene lineages in southwestern Australia and the Cape Region. The novel mediterranean-type climate (MTC) seasonality present since the middle Miocene has allowed colonization of MTEs from a regional species pool with associated diversification. Fire persistence has been a primary driving factor for speciation in four of the five regions. Understanding the regional patterns of plant species diversity among the MTEs involves complex interactions of geologic and climatic histories for each region as well as ecological factors that have promoted diversification in the Neogene and Quaternary. A critical element of species richness for many MTE lineages has been their ability to speciate and persist at fine spatial scales, with low rates of extinction.

Spatial autocorrelation potentially indicates the degree of changes in the predictive power of environmental factors for plant diversity

In the literature of ecological indicators, more attention has yet to be paid to the potential effects of spatial autocorrelation (SAC) on the prediction of plant community structure. At a selected foredune ridge in a temperate coast of South Korea, this research developed two regression models: (1) a non-spatial ordinary least squares (OLS) in which the fine-scale (ca. 10m) variability of diversity was predicted by soil and topographic parameters and (2) a spatial model in which spatial filters extracted by spatial eigenvector mapping were incorporated as additional predictors into the original OLS. After such incorporation, a reduction apparently occurred in the predictive power of the environmental variables, especially those with an inherently high amount of SAC. For example, Mg2+ was the most significant predictor for species diversity in OLS, but it became insignificant in spatial regression. This indicates that, during the incorporation of SAC, the predictive importance of Mg2+ was replaced by that of spatial filters. In other words, because the SAC of Mg2+ was inherently strong (global Moran's I=0.68, p<0.001), this soil attribute became redundant when the spatial filters were added to the non-spatial OLS. These discussions corroborate the general idea of this paper that SAC potentially indicates the degree of shifts in the predictive power of environmental factors for plant diversity. In sum, we suggest that environmental variables, which are highly structured over space, should be the target of special attention and care in future modeling attempts aiming to predict the spatial patterns of plant species diversity in coastal dunes. This fine-scale approach can also be applied to macroecological studies along a variety of ecological systems, spanning latitudinal or disturbance gradients.

Climate vs. topography – spatial patterns of plant species diversity and endemism on a high‐elevation island

Summary Climate and topography are among the most fundamental drivers of plant diversity. Here, we assessed the importance of climate and topography in explaining diversity patterns of species richness, endemic richness and endemicity on the landscape scale of an oceanic island and evaluated the independent contribution of climatic and topographic variables to spatial diversity patterns. We constructed a presence/absence matrix of perennial endemic and native vascular plant species (including subspecies) in 890 plots on the environmentally very heterogeneous island of La Palma, Canary Islands. Species richness, endemic richness and endemicity were recorded, interpolated and related to climate (i.e. variables describing temperature, precipitation, variability and climatic rarity) and topography (i.e. topographic complexity, solar radiation, geologic age, slope and aspect). We used multimodel inference, spatial autoregressive models, variance partitioning and linear regression kriging as statistical methods. Species richness is best explained by both climatic and topographic variables. Topographic variables (esp. topographic complexity and solar radiation) explain endemic richness, and climatic variables (esp. elevation/temperature and rainfall seasonality) explain endemicity. Spatial patterns of species richness, endemic richness and endemicity were in part geographically decoupled from each other. Synthesis. We identified several topography‐dependent processes ranging from evolutionary processes (micro‐refugia, in situ speciation, pre‐adaptation to rupicolous conditions, dispersal limitations) to human‐induced influences (introduced herbivores, fire, land use) that possibly shape the endemic richness pattern of La Palma. In contrast, climate mainly drives endemicity, which is connected to ecological speciation and specialization to local conditions. We highlight the importance of incorporating climatic variability into future studies of plant species diversity and endemism. The spatial incongruence in hot spots of species richness, endemic richness and endemicity emphasizes the need for an integrated conservation approach acknowledging different diversity measures to protect the complete spectrum of diversity. High‐elevation islands such as La Palma are highly suitable to study drivers of diversity and endemism, as they offer environmental gradients of continental magnitude on the landscape scale of a single climatic mini‐continent and a large array of in situ‐speciated endemics.