Experimental tests of the dependence of arthropod diversity on plant diversity

ABSTRACT Because a diversity of resources should support a diversity of consumers, most models predict that increasing plant diversity increases animal diversity. We report results of a direct experimental test of the dependence of animal diversity on plant diversity. We sampled arthropods in a well-replicated grassland experiment in which plant species richness and plant functional richness were directly manipulated. In simple regressions, both the number of species planted ([Formula: see text] transformed) and the number of functional groups planted significantly increased arthropod species richness but not arthropod abundance. However, the number of species planted was the only significant predictor of arthropod species richness when both predictor variables were included in ANOVAs or a MANOVA. Although highly significant, arthropod species richness regressions had low [Formula: see text] values, high intercepts (24 arthropod species in monocultures), and shallow slopes. Analyses of relations among plants and arthropod trophic groups indicated that herbivore diversity was influenced by plant, parasite, and predator diversity. Furthermore, herbivore diversity was more strongly correlated with parasite and predator diversity than with plant diversity. Together with regression results, this suggests that, although increasing plant diversity significantly increased arthropod diversity, local herbivore diversity is also maintained by, and in turn maintains, a diversity of parasites and predators.     

Latitudinal gradients of associations between beta and gamma diversity of trees in forest communities in the New World

Aims We analyze two continental data sets of forest communities from across the New World to examine the latitudinal gradients of beta diversity after accounting for gamma diversity and the latitudinal gradient of gamma diversity after accounting for beta diversity.Methods Correlation and regression analyses were used to relate beta and gamma diversity to latitude along two latitudinal gradients in the New World (one including 72 forest sites located south of the equator and the other including 79 forest sites located north of the equator).Important findings Beta diversity and gamma diversity were negatively correlated with latitude. Beta diversity was strongly and positively correlated with gamma diversity (Pearson's correlation coefficient: 0.783 for New World North and 0.848 for New World South). When beta diversity was regressed on latitude and gamma diversity, 69.8 and 85.7% of the variation in beta diversity were explained, respectively, for New World North and New World South. When gamma diversity was regressed on latitude and beta diversity, 81.8 and 84.3% of the variation in gamma diversity were explained, respectively, for New World North and New World South. After statistically removing the relationship between beta and gamma diversity, latitude has weak or no relationships with beta and gamma diversity. However, strong positive correlations between beta and gamma diversity may not be considered as evidence of one driving the other along a latitudinal gradient.     

Effects of species traits on the genetic diversity of high-mountain plants: a multi-species study across the Alps and the Carpathians

Aim  To test the influence of various species traits, elevation and phylogeographical history on the genetic diversity of high-mountain plants in the Alps and Carpathians.
Location  The regular sampling grid comprised the whole range of the European Alps and the Carpathians.
Methods  Twenty-two high-mountain plant species were exhaustively sampled and their genetic diversity was assessed with amplified fragment length polymorphisms (AFLPs). ANOVAs were used to check for relationships between species traits and species genetic diversity, and to test whether genetic diversity was influenced by altitude and phylogeographical history (i.e. Alps versus Carpathians).
Results  In both mountain systems, species dispersed and pollinated by wind showed higher genetic diversity than species with self or insect pollination, and with animal- or gravity-dispersed seeds. Only in the Alps did altitudinal range size affect species genetic diversity significantly: species with narrow altitudinal ranges in the highest vegetation belts had significantly higher genetic diversity than those expanding over wide altitudinal ranges. Genetic diversity was species specific and significantly higher in the Alps than in the Carpathians, but it was not influenced by elevation.
Main conclusions  Wind pollination and wind dispersal seem to foster high genetic diversity. However, species traits are often associated and their effects on genetic diversity cannot be clearly disentangled. As genetic diversity is species specific, comparisons across species need to be interpreted with care. Genetic diversity was generally lower in the Carpathians than in the Alps, due to higher topographical isolation of alpine habitats in the Carpathians and this mountain massif's divergent phylogeographical history. Elevation did not influence genetic diversity, challenging the long-held view of decreasing genetic diversity with increasing elevation in mountain plants.     

北京东灵山辽东栎林植物物种多样性的多尺度分析

多尺度分析物种多样性格局能够为有效保护生物多样性提供重要信息.利用物种多样性的加法分配法则分析了样方-坡位-坡面等级尺度系统辽东栎林植物物种多样性(gamma多样性)的alpha多样性和beta多样性在各尺度上的分配关系.结果表明以物种丰富度为指标的区域物种多样性的最大贡献来自坡面尺度,表明坡面尺度是维持辽东栎林物种多样性的有效尺度;而对Simpson多样性和Shannon多样性的最大贡献则来自样方内,这决定于群落物种优势度和稀有度格局;各尺度间beta多样性组分随尺度的增大而增大可能是环境异质性和扩散作用的综合结果.各尺度间Shannon多样性对总体多样性的贡献大于Simpson多样性的贡献是偶见种在各尺度间分配的结果.物种多样性分配的加法法则为物种多样性格局的多尺度分析提供了理论框架,是检验物种多样性格局形成机制的有效方法.     

Spatial patterns of dicot diversity in Argentina

In this paper, we analyzed the taxonomic diversity of the Argentine dicots to evaluate their relationships with area, latitude, and longitude. We also evaluated species diversity and higher taxa diversity relationships. The families, genera and species diversity in Argentine dicots was not explained by the area of each province but it varied through latitudinal and longitudinal gradients. The taxonomic diversity of these plants increased from high to low latitudes and west–east longitudes. These patterns would explain why the main diversity centers are located in the North region of this country. As we expected the species diversity and higher taxa diversity showed a positive relationship. At this scale, higher taxa diversity could be use as surrogate for species diversity.     

山西五鹿山森林群落木本植物功能多样性

通过选取群落中木本植物种子的扩散方式、传粉方式、植株高度和盖度等13个功能性状,计算出群落的6个功能多样性指数:功能性状距离、功能性状平均距离、功能体积、功能均匀度、功能分散指数和Rao二次熵指数,结合群落物种丰富度指数、Shannon-Wiener指数和物种均匀度指数对山西五鹿山森林群落木本植物功能多样性进行研究。结果表明:(1)功能性状距离、功能性状平均距离、功能体积与物种丰富度、Shannon-Wiener指数显著正相关;功能均匀度与Shannon-Wiener指数、物种均匀度指数显著正相关;功能分散指数、Rao二次熵指数与物种均匀度指数、Shannon-Wiener指数显著正相关;(2)功能多样性的差异很大程度上是由于物种差异所引起的;(3)6个功能多样性指数可分为三类:功能性状距离、功能性状平均距离、功能体积为功能丰富度指数;功能均匀度为功能均匀度指数;功能分散指数和Rao二次熵指数为功能离散度指数。该分类结果符合指数的计算方法和生态学意义,以及相互独立的标准。     

Host plant genus-level diversity is the best predictor of ectomycorrhizal fungal diversity in a Chinese subtropical forest

Microbial diversity is generally far higher than plant diversity, but the relationship between microbial diversity and plant diversity remains enigmatic. To shed light on this problem, we examined the diversity of a key guild of root-associated microbes, that is, ectomycorrhizal (EM) fungi along a plant diversity gradient in a Chinese subtropical forest. The results indicated that EM fungal diversity was positively correlated with host plant diversity. Furthermore, this relationship was best predicted by host genus-level diversity, rather than species-level diversity or family-level diversity. The generality of this finding was extended beyond our study system through the analyses of 100 additional studies of EM fungal communities from tropical and temperate forests. Here as well, EM fungal lineage composition was significantly affected by EM plant diversity levels, and some EM fungal lineages were co-associated with some host plant genera. These results suggest a general diversity maintenance mechanism for host-specific microbes based on higher order host plant phylogenetic diversity.     

The variation of tree beta diversity across a global network of forest plots

Aims With the aim of understanding why some of the world's forests exhibit higher tree beta diversity values than others, we asked: (1) what is the contribution of environmentally related variation versus pure spatial and local stochastic variation to tree beta diversity assessed at the forest plot scale; (2) at what resolution are these beta‐diversity components more apparent; and (3) what determines the variation in tree beta diversity observed across regions/continents? Location World‐wide. Methods We compiled an unprecedented data set of 10 large‐scale stem‐mapping forest plots differing in latitude, tree species richness and topographic variability. We assessed the tree beta diversity found within each forest plot separately. The non‐directional variation in tree species composition among cells of the plot was our measure of beta diversity. We compared the beta diversity of each plot with the value expected under a null model. We also apportioned the beta diversity into four components: pure topographic, spatially structured topographic, pure spatial and unexplained. We used linear mixed models to interpret the variation of beta diversity values across the plots. Results Total tree beta diversity within a forest plot decreased with increasing cell size, and increased with tree species richness and the amount of topographic variability of the plot. The topography‐related component of beta diversity was correlated with the amount of topographic variability but was unrelated to its species richness. The unexplained variation was correlated with the beta diversity expected under the null model and with species richness. Main conclusions Because different components of beta diversity have different determinants, comparisons of tree beta diversity across regions should quantify not only overall variation in species composition but also its components. Global‐scale patterns in tree beta diversity are largely coupled with changes in gamma richness due to the relationship between the latter and the variation generated by local stochastic assembly processes.     

戴云山物种多样性与系统发育多样性海拔梯度分布格局及驱动因子

生物多样性的海拔分布格局是生态学研究的热点。海拔作为综合性因子驱动着植物群落的物种、系统发育与功能多样性的空间分布。以戴云山南坡900-1600 m森林植物群落为研究对象,探讨物种多样性、系统发育指数与环境驱动因子的相互关系以及环境因子在群落构建与多样性维持中的重要意义。结果表明：（1）森林植物群落的系统发育多样性与物种多样性沿海拔均呈现中间高度膨胀格局。（2）物种多样性Margalef指数、Shannon-Wiener指数与系统发育多样性指数呈显著正相关,表明物种多样性越高,系统发育多样性也越高。Shannon-Wiener指数与物种多样性指数（Margalef、Pielou、Simpson指数）、系统发育多样性及系统发育结构都存在显著相关性,一定程度上Shannon-Wiener指数可以代替其他指数。Pielou指数、Simpson指数、Shannon-Wiener指数与系统发育结构NRI （Net relatedness index）指数、NTI （Net nearest taxa index）指数存在显著正相关,表明群落优势度、均匀度与系统发育结构相关性较强。（3）土壤全磷含量是影响系统发育多样性和物种多样性的主要驱动因子,土壤含水量是影响Shannon-Wiener、Pielou、Simpson指数的最显著因子,海拔是影响群落系统发育结构的主要因素。海拔是影响系统发育结构变化的主要环境因子,而土壤因子是影响物种多样性与系统发育多样性的主要因素,进一步验证了物种多样性与系统发育多样性的高度相关,结果旨在揭示物种群落空间分布规律。     

Effects of genetic diversity of grass on insect species diversity at higher trophic levels are not due to cascading diversity effects

Genetic diversity in plant populations has been shown to affect the species diversity of insects. In grasses, infection with fungal endophytes can also have strong effects on insects, potentially modifying the effects of plant genetic diversity. We manipulated the genetic diversity and endophyte infection of a grass in a field experiment. We show that diversity of primary parasitoids (3rd trophic level) and, especially, secondary parasitoids (4th trophic level) increases with grass genetic diversity while there was no effect of endophyte infection. The increase in insect diversity appeared to be due to a complementarity effect rather than a sampling effect. The higher parasitoid diversity could not be explained by a cascading diversity effect because herbivore diversity was not affected and the same herbivore species were present in all treatments. The effects on the higher trophic levels must therefore be due to a direct response to plant traits or mediated by effects on traits at intermediate trophic levels.     

Ethnic Diversity and Its Environmental Determinants: Effects of Climate, Pathogens, and Habitat Diversity

This article documents, and seeks to explain, the geographical patterning in ethnic group distributions. Some areas, chiefly equatorial regions and areas of high habitat diversity, are crowded with a large number of named groups. Elsewhere, people over a large area consider themselves members of a single group. Using three new codes for the Standard Cross-Cultural Sample (ethnic diversity, habitat diversity, and rainfall variation), I show that regions with relatively few ethnic groups (low ethnic diversity) have unpredictable and highly variable climates and low pathogen loads. In most areas there was no relationship between ethnic diversity and ecosystem productivity, and there was little or none with the chief determinants of productivity, mean annual rainfall and temperature. Habitat diversity was also associated with ethnic diversity, particularly among nonstratified societies. Habitat diversity is correlated with degree of topographic relief, but the effect of habitat diversity on ethnic diversity is larger than, and independent of, the effect of topography. [ ethnic diversity, ecological anthropology, spatial organization, cross-cultural research ]     

城市化景观格局对本土植物多样性的多尺度影响——以北京市顺义区为例

景观格局对植物多样性的影响已经在很多研究中得到了验证,但有关城市景观的影响仍然知之甚少。为了探究城市化景观格局对植物多样性的影响及其尺度效应,本研究在北京市顺义区调查了105个样地,计算每个样地的α和β多样性指数;并以100 m为步长,分析了100～1000 m范围内的10个尺度43个城市的景观格局指数。结果表明: 在所有尺度上,城市景观面积指数、核心类指数和边缘指数与本土植物多样性均呈负相关;形状复杂性指数在小尺度内有利于植物多样性,而面积加权复杂性指数则在较大尺度上影响明显。其他指数如城市斑块的连接性、邻近性、内聚性、破碎性和散布并列指数与本土植物多样性之间的关系轻微且不稳定。城市化强度与尺度呈负相关,与各个尺度的植物多样性呈负相关。合理将城市区域分为许多边缘简单的小斑块,能够更好地保护本土植物多样性。该研究提出了保护城市植物多样性的景观格局建议,为生态城市建设提供参考。     

吉林蛟河针阔混交林林层结构对生产力的影响

探讨不同林层物种多样性和林分结构与森林生产力之间的关系,为森林可持续经营管理策略优化提供理论支持。以吉林蛟河30 hm²针阔混交林固定监测样地中的38432株木本植物的野外调查数据为研究对象,利用结构方程模型探讨了不同林层物种多样性和林分结构多样性对森林生产力的作用机制。结果表明：（1）林冠层林分结构多样性和生产力之间呈负相关关系,路径系数为-0.138;林下层林分结构多样性和生产力之间呈正相关关系,路径系数为0.083。（2）林冠层物种多样性和生产力之间呈正相关关系,路径系数为0.099;林下层物种多样性和生产力之间关系不显著,且物种多样性在林冠层和林下层呈正相关关系,路径系数为0.147。物种多样性和林分结构多样性与森林生产力之间不存在唯一的关系,这种关系的大小、方向和潜在机制与林层有关。为此,在森林经营过程中要充分考虑不同林层物种多样性和林分结构多样性与森林生产力之间的关系。     

Contrasting effects of diversity on the temporal stability of plant populations

Recent theoretical and empirical work suggests that diversity enhances the temporal stability of a community. However, the effect of diversity on the stability of the individual populations within the community remains unclear. Some models predict a decrease of population stability with diversity, whereas others suggest that diversity has a stabilizing effect on populations. Empirical evidence for either relationship between population stability and diversity is weak. The few studies that directly assessed the stability of populations reported contradicting results. We used a six-year data-set from a plant diversity experiment to examine the relationships between diversity and temporal stability of plant biomass. Our results show that stability increased with diversity at the community-level, while the stability of populations, averaged over all species, decreased with diversity. However, when examining species separately we found positive, negative and neutral relationships between population stability and diversity. Our findings suggest that diversity may contribute to the stability of ecosystem services at the community level, but the effect of diversity on the stability of the individual populations within the community are generally negative. However, different species within the community may show strikingly different relationships between diversity and stability.     

Effects of diversity on diversity: consequences of competition and facilitation

Diversity in one group of species or genotypes is often correlated with diversity in a second group – prominent examples including native vs exotic species, and genetic diversity in a focal species vs species diversity in the rest of the community. I used simulation models to investigate the roles of competition and facilitation among species or genotypes in creating diversity–diversity relationships, with a focus on facilitation, which has received little theoretical attention. When competitive interactions dominate, increasing diversity in one group reduces diversity in the second group via filling of available niche space. Facilitation can create positive diversity–diversity relationships via a sampling effect, whereby a strong facilitator of the second group is more likely to be present as diversity increases in the first group, and also via one group acting as a source of biotic heterogeneity (i.e. diversifying selection) on the second group. However, the biotic heterogeneity effect is expected only under restricted conditions – with asymmetric facilitation, only during a transient period, or only over a small range of species diversity levels – and therefore seems unlikely to operate within trophic levels in natural communities. More generally, the simultaneous operation of competition and facilitation results in several different diversity–diversity relationships and underlying mechanisms. The results clarify the potential roles of positive and negative interactions in creating diversity–diversity relationships, and in determining the outcome of community dynamics in general. This study also highlights some important difficulties in incorporating facilitation into ecological theory for communities with many species.     

Response of pollen diversity to the climate-driven altitudinal shift of vegetation in the Colombian Andes

Change in diversity of fossil pollen through time is used as a surrogate for biodiversity history. However, there have been few studies to explore the sensitivity of the measured pollen diversity to vegetation changes and the relationship between pollen diversity and plant diversity. This paper presents results of a study to assess the relationship between pollen diversity and relative abundance of pollen from different altitudinal vegetation belts (subandean forest, Andean forest, subparamo and grassparamo) in three records from the tropical Andes in Colombia. The results indicated that plant diversity in the vegetation declined with altitude and pollen diversity is positively correlated to the abundance of pollen from lower altitude vegetation belts and negatively correlated to that from the grassparamo. These results, therefore, suggest that pollen diversity coarsely reflects the diversity of the surrounding vegetation. Using this interpretation, we were able to predict changes in plant diversity over the past 430000 years in the Colombian Andes. Results indicated that under warmer climatic conditions, more species-diverse vegetation of low elevation moved upslope to contribute more pollen diversity to the study sites, and under colder conditions, species-poor grassparamo moved downslope and observed pollen diversity was lower. This study concludes that fossil pollen diversity may provide an important proxy to reconstruct the temporal changes in plant diversity.     

Geostatistical approaches and optimal additional sampling schemes for spatial patterns and future sampling of bird diversity

Aim To evaluate geostatistical approaches, namely kriging, co‐kriging and geostatistical simulation, and to develop an optimal sampling design for mapping the spatial patterns of bird diversity, estimating their spatial autocorrelations and selecting additional samples of bird diversity in a 2450 km² basin. Location Taiwan. Methods Kriging, co‐kriging and simulated annealing are applied to estimate and simulate the spatial patterns of bird diversity. In addition, kriging and co‐kriging with a genetic algorithm are used to optimally select further samples to improve the kriging and co‐kriging estimations. The association between bird diversity and elevation, and bird diversity and land cover, is analysed with estimated and simulated maps. Results The Simpson index correlates spatially with the normalized difference vegetation index (NDVI) within the micro‐scale and the macro‐scale in the study basin, but the Shannon diversity index only correlates spatially with NDVI within the micro‐scale. Co‐kriging and simulated annealing simulation accurately simulate the statistical and spatial patterns of bird diversity. The mean estimated diversity and the simulated diversity increase with elevation and decrease with increasing urbanization. The proposed optimal sampling approach selects 43 additional sampling sites with a high spatial estimation variance in bird diversity. Main conclusions Small‐scale variations dominate the total spatial variation of the observed diversity due to a lack of spatial information and insufficient sampling. However, simulations of bird diversity consistently capture the sampling statistics and spatial patterns of the observed bird diversity. The data thus accumulated can be used to understand the spatial patterns of bird diversity associated with different types of land cover and elevation, and to optimize sample selection. Co‐kriging combined with a genetic algorithm yields additional optimal sampling sites, which can be used to augment existing sampling points in future studies of bird diversity.     

庙岛群岛典型植物群落物种、功能、结构多样性及其对环境因子的响应

海岛植被在全球生物多样性研究中起重要作用,研究海岛植被多样性对于理解海陆相互作用下植物群落的多样性维持机制有重要意义.本研究以庙岛群岛的麻栎群落、刺槐群落、黑松群落、荆条群落4种典型植物群落为对象,采用物种多样性指数、功能多样性指数和结构多样性指数,在群落尺度上探讨了海岛典型植物群落物种、功能、结构多样性间的关系及其对环境因子的响应.结果表明: 黑松群落的物种丰富度与Rao指数高于刺槐群落与麻栎群落,而结构多样性却较低;荆条灌丛的物种、结构多样性均低于森林群落,而功能多样性高于部分森林群落.物种丰富度与Rao指数以及树高多样性间呈显著正相关,与功能均匀度呈显著负相关.结构多样性主要由坡度决定且与坡度呈负相关;功能均匀度与坡度呈正相关,而功能异质性、功能离散度和物种多样性则更多地受土壤理化性质的影响,与土壤容重及土壤总碳呈正相关,与土壤含水率呈负相关.总体而言,庙岛群岛的植物群落多样性格局既有与大陆植被相似的特征,但也有其海岛特殊性.     

Structural diversity promotes productivity of mixed,uneven-aged forests in southwestern Germany

Forest diversity-productivity relationships have been intensively investigated in recent decades. However, few studies have considered the interplay between species and structural diversity in driving productivity. We analyzed these factors using data from 52 permanent plots in southwestern Germany with more than 53,000 repeated tree measurements. We used basal area increment as a proxy for productivity and hypothesized that: (1) structural diversity would increase tree and stand productivity, (2) diversity-productivity relationships would be weaker for species diversity than for structural diversity, and (3) species diversity would also indirectly impact stand productivity via changes in size structure. We measured diversity using distance-independent indices. We fitted separate linear mixed-effects models for fir, spruce and beech at the tree level, whereas at the stand level we pooled all available data. We tested our third hypothesis using structural equation modeling. Structural and species diversity acted as direct and independent drivers of stand productivity, with structural diversity being a slightly better predictor. Structural diversity, but not species diversity, had a significant, albeit asymmetric, effect on tree productivity. The functioning of structurally diverse, mixed forests is influenced by both structural and species diversity. These sources of trait diversity contribute to increased vertical stratification and crown plasticity, which in turn diminish competitive interferences and lead to more densely packed canopies per unit area. Our research highlights the positive effects of species diversity and structural diversity on forest productivity and ecosystem dynamics.