Host-plant preference of Brachypterolus pulicarius, an inadvertently introduced biological control insect of toadflaxes

Brachypterolus pulicarius (L.) (Coleoptera: Kateridae) is an inadvertently introduced biological control agent that can reduce seed set in two North American invasive species, yellow (Linaria vulgaris P. Mill.) (Scrophulariaceae) and Dalmatian toadflax (Linaria genistifolia (L.) P. Mill. ssp. dalmatica). The beetles are more common on yellow toadflax than on Dalmatian toadflax. To understand their distribution on the two host plants, we investigated whether they prefer one host to the other and whether individuals aggregate toward conspecifics. In field and laboratory experiments where beetles were presented with a choice of both toadflax species, B. pulicarius sampled from both host plants preferred yellow toadflax. However, in the laboratory experiment, beetles collected from Dalmatian toadflax showed a weaker preference for yellow toadflax than beetles collected from yellow toadflax. In the field experiment, all beetle populations sampled showed similar preferences. When given a choice between yellow toadflax plants with and without trapped adult B. pulicarius, beetles preferred plants with conspecifics, suggesting aggregation toward beetle pheromones or host‐plant volatiles induced by beetle activity. These results do not support the current practice of redistributing North American B. pulicarius onto Dalmatian toadflax because of their preference for yellow toadflax.     

Harvester ants modify seed rain using nest vegetation and granivory

1. In annual plant communities, the seed bank determines each generation's potential emergence and any factor that influences it could alter community structure. Harvester ants are common seed predators that may cause seed sources and seed rain composition to vary. 2. In semi‐arid shrubland of the Negev desert of Israel, we hypothesised that the positive effects of dense vegetation on nests of the harvester ant Messor ebeninus Sant. would outweigh reduction by granivory. 3. To test whether nests were seed sources, we removed vegetation on 10 of 20 sampled nests prior to seeding. We tested the interaction between seed sources and granivory by locating seed traps at three locations: nests, foraging trails, and unvisited areas. Trapped seeds were recorded during spring and summer dispersal. Plant recruitment from the altered seed bank was recorded the following spring. 4. During April, seeds were more abundant near nests than the other locations and at uncut compared with cut nests. Foraging trails had fewer species and higher equitability compared with nests or unvisited areas. May and June to August had highest species richness at nests, but richness of cut and uncut nests were similar. Ordination of plant recruitment showed slightly lower vegetation community variation by diminished species in the cut seed bank. 5. While intact nest vegetation initially had high abundance of locally deposited seeds, it apparently blocked wind‐dispersed seeds later in the summer. Conversely, granivory reduced seed species richness only on trails and decreased dominance structure by preferential removal of some species.     

Defining a Target Map of Native Species Assemblages for Restoration

Vegetation restoration is usually based on predefined species assemblages from large‐scale maps of potential vegetation. However, most restoration plans apply to smaller spatial scales, so a homogeneous species assemblage is usually assigned to the target site. We propose defining species assemblages for restoration by modeling the distribution of individual target species. The example presented here is about postfire restoration, but it can be used in other types of disturbed areas. We surveyed 212 plots in well‐preserved vegetation around the burned area to obtain a list of target species and physical parameters of the plots. The burned area was divided in a grid of 723 squares, 1 ha each, and then characterized according to the same physical parameters. From these data, we modeled the distribution of 23 target species. A target map of predicted species assemblages was built combining species maps. This map largely resembles the native vegetation in terms of species richness per plot, environmental gradients in α‐diversity, spatial variation in β‐diversity, and frequency of species occurrence. Comparison between the target map and the current vegetation (recovery status) indicated that, on average, only half of the potential set of species is already present in each plot. Analysis of the recovery status suggested that both rock outcrops and areas at lower altitude, with gentle slope and deeper soil, recover faster. This illustrates the utility of target maps to outline plots in more need of restoration.     

Land‐use and fire history effects on post‐fire vegetation dynamics in eastern Spain

Question: Is post‐fire, medium‐term vegetation dynamics determined by land‐use or fire history prior to fire? Location: South‐facing slope in the Gallinera valley, Alicante province, eastern Spain. Methods: After mapping the land‐use and fire history of the study site using photo‐interpretation, we sampled vegetation structure on a set of plots representing the most frequent land‐use and fire history combinations on an area burned six years before sampling. We studied the effects of land‐use history, comparing the one‐fire land‐use trajectories. We analysed the effects of fire history; comparing one‐ and two‐fire plots for both previously cropped and uncropped areas. Results: Most variables were not significantly different between the earliest abandoned plots (abandoned at least 38 years before the fire) and the uncropped plots. On the most recently abandoned plots (abandoned between one and four years before the fire), the therophyte richness and the ratio of seeder: resprouter richness were significantly greatest. Different fire recurrences did not determine different post‐fire vegetation on either the uncropped or the early abandoned plots (all dominated by fire‐recruited seeder shrubs). The most recently abandoned plots had a lower resilience to fire. Conclusions: Land‐use history and recent pre‐fire land use, in particular, determined the post‐fire vegetation in the medium term. The vegetation composition converged during secondary succession among land‐use histories. Increasing fire recurrence had a small effect on mature plant communities, due to the combination of life‐history traits determining the response to fire of the dominant species.     

A nested-intensity design for surveying plant diversity

Managers of natural landscapes need cost-efficient, accurate, and precise systems to inventory plant diversity. We investigated a nested-intensity sampling design to assess local and landscape-scale heterogeneity of plant species richness in aspen stands in southern Colorado, USA. The nested-intensity design used three vegetation sampling techniques: the Modified-Whittaker, a 1000-m² multiple-scale plot (n = 8); a 100-m² multiple-scale Intensive plot (n = 15); and a 100-m² single-scale Extensive plot (n = 28). The large Modified-Whittaker plot (1000 m²) recorded greater species richness per plot than the other two sampling techniques (P < 0.001), estimated cover of a greater number of species in 1-m² subplots (P < 0.018), and captured 32 species missed by the smaller, more numerous 100-m² plots of the other designs. The Intensive plots extended the environmental gradient sampled, capturing 17 species missed by the other techniques, and improved species–area calculations. The greater number of Extensive plots further expanded the gradient sampled, and captured 18 additional species. The multi-scale Modified-Whittaker and Intensive designs allowed quantification of the slopes of species–area curves in the single-scale Extensive plots. Multiple linear regressions were able to predict the slope of species–area curves (adj R ² = 0.64, P < 0.001) at each Extensive plot, allowing comparison of species richness at each sample location. Comparison of species–accumulation curves generated with each technique suggested that small, single-scale plot techniques might be very misleading because they underestimate species richness by missing locally rare species at every site. A combination of large and small multi-scale and single-scale plots greatly improves our understanding of native and exotic plant diversity patterns.     

Species Richness, Community Specialization and Soil-Vegetation Relationships of Managed Grasslands in a Geologically Heterogeneous Landscape

The increasing importance of the conservation value of managed grasslands has led to many studies exploring edaphic determinants of grassland biodiversity. Most studies, however, come either from very large areas, where biogeographical factors such as dispersal limitation may play a role, or from small, but ecologically rather uniform, regions. In addition, few studies further distinguish between plant specialists and generalists in the interpretation of the observed patterns. Here we studied species richness in semi-natural, managed grasslands in the Strá?ovské vrchy Mountains in the West Carpathians, Slovakia, where there is a matrix of different bedrocks (crystalline, sandstone, claystone, limestone) on a steep altitudinal gradient. In 89 vegetation plots we sampled the species composition of vascular plants and bryophytes and measured soil chemistry, slope angle, heat index, altitude and soil depth. We further applied Ellenberg indicator values and classified species into community specialists or generalists based on the analysis of a large phytosociological database. Using cluster analysis, we delimited five vegetation types that clearly differed in response to soil characteristics. Species richness varied between 19 and 64 species per 16?m². The main compositional gradient correlated with measured soil pH and calcium, but species richness was not significantly correlated with these factors. Soil available phosphorus was not associated with species composition as has been found elsewhere, but it did correlate negatively with species richness and the richness of specialists. Overall, species richness was largely driven by the number of specialists in the plot and particular vegetation types differed conspicuously in their number. We further found significant effects of iron, potassium and sodium on species richness, species composition and the representation of specialists and generalists. Our results provide new insights into the determinants of diversity in managed grasslands as well as to the theoretical species pool concept, explaining species richness variation along a pH gradient.     

Colonisation by a dominant ant facilitated by anthropogenic disturbance: effects on ant assemblage composition, biomass and resource use

Dominant species are thought to regulate species composition and assemblage structure. Invasion by a dominant species is thus likely to alter assemblages and anthropogenic disturbance often facilitates such invasions. In this study we examined the association of a dominant ant, Iridomyrmex purpureus , native to south-eastern Australia, with fire trails in national parks and its effects on ant assemblages. Association with fire trails was examined by comparing the numbers of I. purpureus nests on transects along fire trails with those in transects through surrounding vegetation. Ant assemblages and habitat characteristics of eight sandstone outcrops that supported colonies of I. purpureus were compared with those on eight that did not in summer and autumn 2000. We examined ant species richness, abundance, composition and biomass using quadrats, and resource use with Acacia botrycephalus seeds placed on rock and in vegetation. I. purpureus nests were considerably more common along fire trails than in surrounding vegetation. Sites with I. purpureus had similar species richness to those without, but a lower abundance and biomass of other ants and a different assemblage composition. These differences could not be attributed to any differences in measured habitat characteristics. Ecologically similar species, particularly other species of Iridomyrmex , were less abundant in areas with I. purpureus . While the biomass of other species was suppressed in areas with I. purpureus , the biomass of the dominant was several times that of the assemblage of other ants, a pattern shared with assemblages invaded by exotic species. In areas with I. purpureus , seeds were removed more rapidly from rock, but not vegetation, indicating that resources on rock may be under-exploited by other species. Regulation of invaded ant assemblages by this dominant ant is thus limited to functionally similar species, and this may be due to its use of resources that are unexploited in its absence.     

Vascular plant species richness along environmental gradients in a cool temperate to sub-alpine mountainous zone in central Japan

In order to clarify how vegetation types change along the environmental gradients in a cool temperate to sub-alpine mountainous zone and the determinant factors that define plant species richness, we established 360 plots (each 4 × 10 m) within which the vegetation type, species richness, elevation, topographic position index (TPI), slope inclination, and ground light index (GLI) of the natural vegetation were surveyed. Mean elevation, TPI, slope inclination, and GLI differed across vegetation types. Tree species richness was negatively correlated with elevation, whereas fern and herb species richness were positively correlated. Tree species richness was greater in the upper slope area than the lower slope area, whereas fern and herb species richness were greater in the lower slope area. Ferns and trees species richness were smaller in the open canopy, whereas herb species richness was greater in the open canopy. Vegetation types were determined firstly by elevation and secondary by topographic configurations, such as topographic position, and slope inclination. Elevation and topography were the most important factors affecting plant richness, but the most influential variables differed among plant life-form groups. Moreover, the species richness responses to these environmental gradients greatly differed among ferns, herbs, and trees.     

Restoration of Wet Dune Slacks on the Dutch Wadden Sea Islands: Recolonization After Large-Scale Sod Cutting

The effects of sod cutting were studied in a dune area on the Dutch Wadden Sea Island of Texel. Sod cutting was carried out in a range of different dune slacks in order to restore dune slack vegetation with many endangered Red List species. Sod cutting removed approximately 96% of the soil seed bank. Species abundant in the seed bank, notably Juncacea, also had a high frequency in the vegetation that established during the first year after the restoration measures. Many other species not registered in the seed bank or in the former vegetation also appeared. Species richness in the monitored plots exceeded that of uncut reference plots after a few years. Colonization rates were higher than extinction rates in most plots, indicating that a stable state has not been reached after 5 years. Differences in species richness between slacks appeared to be related to the occurrence of source areas nearby and availability of dispersal agents, such as flooding and animals.     

Small mammal abundance in Mediterranean post-fire habitats: a role for predators?

We studied patterns of small mammal abundance and species richness in post-fire habitats by sampling 33 plots (225 m² each) representing different stages of vegetation recovery after fire. Small mammal abundance was estimated by live trapping during early spring 1999 and vegetation structure was sampled by visual estimation at the same plots. Recently–burnt areas were characterised by shrubby and herbaceous vegetation with low structural variability, and unburnt areas were characterised by well developed forest cover with high structural complexity. Small mammal abundance and species richness decreased with time elapsed since the last fire (from 5 to at least 50 years), and these differences were associated to the decreasing cover of short shrubs as the post-fire succession of plant communities advanced. However, relationships between vegetation structure and small mammals differed among areas burned in different times, with weak or negative relationship in recently burnt areas and positive and stronger relationship in unburnt areas. Furthermore, the abundance of small mammals was larger than expected from vegetation structure in plots burned recently whereas the contrary pattern was found in unburned areas. We hypothesised that the pattern observed could be related to the responses of small mammal predators to changes in vegetation and landscape structure promoted by fire. Fire-related fragmentation could have promoted the isolation of forest predators (owls and carnivores) in unburned forest patches, a fact that could have produced a higher predation pressure for small mammals. Conversely, small mammal populations would have been enhanced in early post-fire stages by lower predator numbers combined with better predator protection in areas covered by resprouting woody vegetation.     

Long‐term effects of exclusion of grazing stock on degraded herbaceous plant communities in a riparian Eucalyptus camaldulensis forest in south‐eastern Australia

Abstract Stock grazing has degraded many riparian ecosystems around the world. However, the potential for ecosystem recovery following the removal of grazing stock is poorly known. We developed a conceptual model to predict the responses of native and exotic herbaceous plants to grazing exclusion, based on site productivity and the degree of initial vegetation degradation. The effects of excluding grazing stock on richness, cover and composition of herbaceous plants were examined over 12 years in the degraded understorey of a riparian forest in Gulpa Island State Forest in south‐eastern Australia. We predicted that grazing exclusion would lead to limited changes in vegetation cover, richness and composition, owing to presumed low site productivity and the high degree of understorey degradation. Results showed that the cover, richness and composition of native and exotic species varied significantly among years. Over all plots, regions and years, total cover was slightly but significantly lower in grazed than in ungrazed plots (43.4% vs. 50.8%). While the cover of native plants increased over time in both treatments, the rate of increase was slightly greater in ungrazed plots. Grazing exclusion had no effect on the richness of native or exotic species, but had a significant but minor impact on plant composition, with different common species (mostly exotics) being promoted or diminished in ungrazed plots. The composition of grazed and ungrazed areas did not become more different over time. Overall, the effects that could be attributed to grazing exclusion were relatively minor and transient. Results are consistent with predictions based on site productivity and initial degradation, and should not be extrapolated to other more productive, or less degraded, riparian systems.     

Riparian bryophyte communities on Madeira: patterns and determinants of species richness and composition

Abstract

We studied 16 streams evenly distributed over the northern and southern slopes of Madeira in order to investigate the riparian bryoflora. Within each stream, three positions (upper, middle and lower reaches) were delimited and within each position two areas were selected. Within each area two plots (each composed of six microplots of 0.2 m²) were sampled, one in the within-stream habitat (submerged all year round), and the other in the stream-border habitat (submerged only in winter). We found that species composition of the riparian bryophytes is affected by the habitat and position in the stream, but not by the main aspect (northern versus southern slope). Concerning species richness, we found that the stream-border community was clearly richer than the within-stream community, upstream plots were richer than plots downstream, and plots on the northern slope of the island were richer than plots on the southern slope. Habitat type was the most significant factor in determining the richness of the threatened species with more species present in the stream-border habitat. Additive partitioning showed that the between-stream component contributed most to total species richness, especially to the richness of the infrequent and threatened species. However, for the common species, the lowest level, i.e. the within-area component, was the most important. Although northern upstream areas are climatically favourable for many bryophyte species due to their higher humidity, the clear effects found may not only be climate-induced, as these areas are also less disturbed and mostly covered by the natural laurel forest. In the southern, downstream parts only a few species were present. Human impacts are largest in the latter situations and probably contributed to the low species richness. As the streams differed considerably in terms of their bryophyte flora, and most of the species were rare, changes in the riparian areas can greatly affect the bryoflora. Therefore, in order to protect the riparian bryophytes as comprehensively as possible, we emphasize the need for careful monitoring of any changes.     

雅鲁藏布江河岸植物物种丰富度分布格局及其环境解释

沿环境梯度物种多样性的分布格局及其环境影响因子的研究是生态学研究的重点内容之一。雅鲁藏布江是我国海拔最高的大河, 目前还没有针对其流域的河岸植物群落物种丰富度分布格局的系统研究。作者沿海拔梯度从雅鲁藏布江上游源头区至下游共设置了15个海拔样带, 在每个海拔样带随机取6个5 m×5 m样方, 共对90个样方的河岸植物群落物种组成和植被类型进行了调查, 共记录到238种维管束植物。DCA排序结果表明物种组成变化主要受海拔和经度控制。CCA排序区分出5种大的植被类型, 即高寒草甸或高寒草原、高山草原、两种亚高山灌丛草原和林缘灌丛植被。各植被类型的分布和变化主要受海拔和经度影响。雅鲁藏布江河岸植物物种丰富度沿海拔和经度梯度呈浅“U”形分布格局, 物种丰富度与年均降水量和植被盖度成显著正相关。     

先锋种丰富度对边坡植被群落特征及其护坡效益的影响

乡土植物灌木化建植是高速公路边坡防护的重要途径。以成渝高速(G85)永川段为例,以西南地区两种典型的边坡绿化初始配置"慈竹(Neosino calamus affinis)+野牛草(Buchloe dactyloides)"、"棉槐(Amorpha fruticosa)+紫羊茅(Festuca rubra)"为基础,分别与马棘(Indigofera pseudotinctoria Mats.)、黄荆(Vitex negundo)、狗牙根(Cynodon dactylon)、芒(Miscanthus sinensis)等路域优势种以不同方式组合,研究一定立地条件下初始绿化植物(先驱植物)的丰富度对边坡植被群落生长发育、早期演替行为及护坡性能的影响。结果表明:1)先驱植物丰富度可直接影响边坡植被的成坪时间、生物量积累:相同建植条件(边坡条件、播种密度等)下,先锋种种类越多,成坪时间就越短,被积累的生物量也越多;2)先锋种数量与群落的生物多样性水平有关(R20.954):相同演替阶段内,先锋种越多,群落的多样性水平(如物种丰富度、Shannon-Wiener指数、Pielou指数)则越高;3)群落中物种多样性水平与植被的护坡性能密切相关(R20.998):多样性水平越高,植被的蓄水、保土能力越强,边坡内径流系数、土壤侵蚀模数越小。可见,在边坡条件、播种密度等建植条件与建植措施一致的情形下,提高初始绿化植物的物种数可有效改善边坡植被的护坡性能。     

Effects of sampling teams and estimation methods on the assessment of plant cover

Abstract. We evaluated variability in cover estimation data obtained by (1) two sampling teams who double sampled plots and (2) one team that used two methods (line intercepts and visual estimation of cover classes) to characterize vegetation of herbaceous wetlands. Species richness and cover estimates were similar among teams and among methods, but one sampling team scored cover higher than the other. The line intercept technique yielded higher cover estimates but lower species richness estimates than the cover class method. Cluster analyses of plots revealed that 36% and 11% of plots sampled consecutively by two teams or using two methods, respectively, were similar enough in species composition and abundance to be paired together in the resulting clustering tree. Simplifying cover estimate data to presence/absence increased the similarity among both teams and methods at the plot scale. Teams were very similar in their overall characterization of sites when cover estimation data were used, as assessed by cluster analysis, but methods agreed best on their overall characterization of sites when only presence/absence data were considered. Differences in abundance estimates as well as pseudoturnover contribute to variability. For double sampled plots, pseudoturnover was 19.1%, but 57.7% of pseudo‐turnover cases involved taxa with ≤ 0.5% cover while only 3.4% involved taxa with > 8% cover. We suggest that vegetation scientists incorporate quality control, calibrate observers and publish their results.     

Extrafloral nectar as a driver of arboreal ant communities at the site‐scale in Brazilian savanna

Despite years of study, it remains unclear if and to what extent the effects of extra‐floral nectaries (EFNs) on arboreal ants observed on individual trees scale up to larger spatial scales. Here, we address this issue in Brazilian savanna and tested three predictions: (i) Trees with EFN have higher richness of arboreal ant species than trees without; (ii) Arboreal ant species richness increases with the proportion of total EFN‐bearing trees at the site scale, due to a higher occurrence of non‐core ant species; (iii) Ant species composition changes with the proportion of EFN‐bearing trees at the site scale. We sampled arboreal ants in 32 plots with EFN‐bearing trees ranging from 0% to 60% of all trees. We sampled 72 ant species, from which 17 (mostly belonging to Camponotus, Cephalotes and Crematogaster) were identified as core species in at least one of the ant‐EFN networks in the 32 plots. Ant species richness was significantly higher on EFN‐bearing trees. We identified 11 ant species that preferentially occurred on EFN‐bearing trees, all of which were core partners in networks. Species richness at the site scales increased with the proportion of EFN‐bearing trees, regardless of tree density and richness; this pattern was due to a higher occurrence of non‐core ant species. Finally, species composition also varied with the proportion of EFN‐bearing trees. Therefore, we found that the presence of EFNs not only influences arboreal ants on individual trees but also has a substantial effect on the ant‐EFN network on a broader community scale. The increase in non‐core species site scale reveals that this interaction is unlikely to result in substantially enhanced protection services for EFN‐bearing plants.     

Floristic composition and analysis of spontaneous vegetation of Sabkha Djendli in north-east Algeria

We conducted a phyto-ecological analysis of the Sebkha Djendli located in the semi-arid lands of the north-eastern Algeria in order to contribute in the understanding of flora composition, diversity and factors controlling plant zonation. Eight plots, distributed on the cardinal and intercardinal points of the site, were sampled. A floristic analysis (species richness, life forms, spatial occurrence, plant cover rate and similarity) and an assessment of the effect of soil salinity and pH on the cover of dominant halophytes were performed. The results of the floristic approach showed the presence of 51 species belonging to 21 families and 45 genera. The most frequent biological types were therophytes (58%) followed by chamaephytes (18%). Vegetation cover rate ranged from 50% to 95%. The distribution of vegetation all around the edges of the Sabkha revealed the dominance of halophytic species belonging to the family Chenopodiaceae. The variation of total halophytic vegetation cover over all sampled plots seems to be affected neither by the distance from waterbody nor by plot orientation nor by the electrical conductivity and pH of soil.     

Ecological Distribution and Community Analysis of Tardigrada from Choccolocco Creek, Alabama

A seasonal survey of tardigrade populations in the riparian zone of the Choccolocco Creek, Alabama, was undertaken from August 1994 through December 1995. Six sites within the riparian zone were sampled in different portions of the creek. At each site, 3 trees with cryptogams were sampled six times during survey period. From a total of 108 samples, 1,588 tardigrades were extracted and individually mounted on slides in Hoyer's medium. The community was dominated (86%) by specimens in the genus Macrobiotus. One species of Echiniscus was new to science and will be described in a separate paper. No significant difference was found between tardigrade occurrence (total number of individuals) and season, moss genera, or tree species. However, there was a significant relationship between the number of tardigrades and site, indicating the need for additional replicate samples. Simpson's and Shannon-Wiener's species diversity indices indicated that species richness and evenness were low. Jaccard's and Standard's community similarity indices suggested that the communities within the riparian zone were dissimilar along Choccolocco Creek.     

Tropical forest structure and diversity in relation to altitude and disturbance in a Biosphere Reserve in central India

Questions: Is species diversity affected in protected areas where human activities are permitted or tolerated? On plots of a fixed size, does stem density alone predict number of species? Are differences in density related to disturbance and altitude? Location: Achanakmar‐Amarkantak Biosphere Reserve, central India. Methods: 42 sites, each with three replicate 10‐m radius plots, were examined. All trees (≥ 30 cm GBH) in each plot were measured for girth at breast height. α‐diversity, species richness and evenness were calculated for each site. The sites were ordinated by Nonmetric Multidimensional Scaling (NMS) using relative importance values of component species. Correspondence Analysis was used to broadly delineate communities. Anthropogenic disturbances were recorded in terms of percentage of trees lopped, scale of lopping, number of domestic livestock dung piles and foot trails (both livestock and people) for each plot. Results: The NMS analysis exhibited a near linear arrangement of sites with no evidence of discrete vegetation zones. NMS axes were significantly related to altitude and disturbance scores. With increasing elevation, basal area increased but number of species, α‐diversity and its components declined monotonically. The number of species and indices of species diversity were positively associated with tree lopping and also with total disturbance. Number of species was controlled by stem density only in plots not dominated by Shorea robusta. Conclusions: Recent levels of human disturbance are associated with higher species diversity in this biosphere reserve. There is some evidence that stands at all altitudes follow the same successional pattern to dominance by Shorea, a successional pattern that also results in decreased diversity without disturbance.     

Plant diversity patterns and their relationships with soil and climatic factors along an altitudinal gradient in the middle Tianshan Mountain area, Xinjiang, China

Patterns of plant diversity along the altitudinal gradient of Tianshan in central Xinjiang, China were examined. Plant and environment characteristics were surveyed from higher, south of Bogeda peak, to lower, north of Guerbantonggute desert. There were a total of 341 vascular plant, 295 herbage, 41 shrub, and seven tree species in the sampled plots. The plant richness of vegetation types generally showed a unimodal pattern along altitude, with a bimodal change of plant species number at 100-m intervals of altitudinal samples. The two belts of higher plant richness were in transient areas between vegetation types, the first in areas from dry grass to forest, and the second from forest to sub-alpine grass and bush. The beta diversity varied with altitudinal changes, with herbaceous species accounting for most species, and thus had similar species turnover patterns to total species. Matching the change of richness of plant species to environmental factors along altitude and correlating these by redundancy analysis revealed that the environmental factors controlling species richness and its pattern were the combined effects of temperature, precipitation, soil water, and nutrition. Water was more important at low altitude, and temperature at high altitude, and soil chemical and physical characters at middle altitudes. This study provides insights into plant diversity conservation of Bogeda Natural Reserve Areas in Tianshan Mountain. Nomenclatures: the scientific name for plants follows Flora of China (Compiling Committee of Flora of China).