Nonmetric Multidimensional Scaling Axes Research Articles

Mapping Floristic Patterns of Trees in Peruvian Amazonia Using Remote Sensing and Machine Learning

Recognition of the spatial variation in tree species composition is a necessary precondition for wise management and conservation of forests. In the Peruvian Amazonia, this goal is not yet achieved mostly because adequate species inventory data has been lacking. The recently started Peruvian national forest inventory (INFFS) is expected to change the situation. Here, we analyzed genus-level variation, summarized through non-metric multidimensional scaling (NMDS), in a set of 157 INFFS inventory plots in lowland to low mountain rain forests (<2000 m above sea level) using Landsat satellite imagery and climatic, edaphic, and elevation data as predictor variables. Genus-level floristic patterns have earlier been found to be indicative of species-level patterns. In correlation tests, the floristic variation of tree genera was most strongly related to Landsat variables and secondly to climatic variables. We used random forest regression, under varying criteria of feature selection and cross-validation, to predict the floristic composition on the basis of Landsat and environmental data. The best model explained >60% of the variation along NMDS axes 1 and 2 and 40% of the variation along NMDS axis 3. We used this model to predict the three NMDS dimensions at a 450-m resolution over all of the Peruvian Amazonia and classified the pixels into 10 floristic classes using k-means classification. An indicator analysis identified statistically significant indicator genera for 8 out of the 10 classes. The results are congruent with earlier studies, suggesting that the approach is robust and can be applied to other tropical regions, which is useful for reducing research gaps and for identifying suitable areas for conservation.

Environmental and Fish Assemblage Contrasts in Blackwater and Clearwater Streams

AbstractWe compared 15 blackwater and clearwater streams in coastal drainages of Alabama by quantifying fish assemblages and associated environmental conditions across multiple seasons and characterizing potential relationships using multivariate statistical approaches. Clearwater stream channels tended to be deeper, to have sandier substrates, and to have higher dissolved oxygen concentrations than blackwater streams. In contrast, blackwater streams showed higher dissolved organic carbon levels and higher benthic macroinvertebrate densities. Discriminant function analysis based on environmental and invertebrate data resulted in 90% discrimination between the two stream types. Nonmetric multidimensional scaling (NMDS) of seasonal fish assemblages indicated separation by stream type, with no overlap in fish assemblages of blackwater and clearwater streams in any season, and 12 (39%) of the 31 species captured were indicative of stream type. A suite of environmental and biological variables representing invertebrate density, discharge, stream size, water chemistry, and land use was correlated with NMDS axes separating fish assemblages by stream type. Fish traits were somewhat distinctive between stream types, as there were unique lie‐in‐wait predators and short‐lived species in each stream type. A fourth‐corner analysis indicated potential linkages between fishes preferring woody substrate and stream type, further suggesting that stream type may explain fish functional structure. These results emphasize the need to consider these coastal systems as biotically unique ecosystem types in conservation plans as well as to focus more attention on better understanding the diversity patterns in headwater streams within the Coastal Plains region.

Radar vision in the mapping of forest biodiversity from space

Recent progress in remote sensing provides much-needed, large-scale spatio-temporal information on habitat structures important for biodiversity conservation. Here we examine the potential of a newly launched satellite-borne radar system (Sentinel-1) to map the biodiversity of twelve taxa across five temperate forest regions in central Europe. We show that the sensitivity of radar to habitat structure is similar to that of airborne laser scanning (ALS), the current gold standard in the measurement of forest structure. Our models of different facets of biodiversity reveal that radar performs as well as ALS; median R² over twelve taxa by ALS and radar are 0.51 and 0.57 respectively for the first non-metric multidimensional scaling axes representing assemblage composition. We further demonstrate the promising predictive ability of radar-derived data with external validation based on the species composition of birds and saproxylic beetles. Establishing new area-wide biodiversity monitoring by remote sensing will require the coupling of radar data to stratified and standardized collected local species data.

Identifying temporal and spatial patterns of diatom community change in the tropical Andes over the last c. 150 years

AbstractAimLakes in the Ecuadorean Andes span different altitudinal and climatic regions, from inter Andean plateau to the high‐elevation páramo, which differ in their historical evolution in the several centuries since the pioneering Humboldt expeditions. Here, we evaluate temporal and spatial patterns of change in diatom assemblages between historical (palaeolimnological) and modern times.LocationEcuadorean AndesMethodsWe compared historical (pre‐1850) and modern (2017) diatom assemblages from 21 lakes and determined the relative role of environmental (water chemistry and climate) and spatial factors (distance‐based Moran's eigenvectors maps) on both assemblages using non‐metric multidimensional scaling (NMDS) with environmental fitting. In addition, we used redundancy analysis (RDA) with variance partitioning to estimate the historical (measured using downcore assemblage composition) effects on modern diatom assemblages and identified diatom species that contributed most to dissimilarity between the two times.ResultsDiatom changes between the two time points were limited across the group of lakes, as indicated by the NMDS ordination. Variance partitioning indicated that modern diatom assemblages were affected by environmental and spatial effects, but with non‐significant effects of past diatom species composition. Ordination results showed that variables related to elevation and water chemistry affected both modern and historical diatom assemblages. Diatom species with the best fit on NMDS axes (i.e. >70%) were influenced by elevation and climatic variables. The most distinctive change between the two time periods was the higher relative abundance of planktic diatom species in top‐core assemblages of some lakes, but in a highly variable fashion across gradients of increased elevation and water depth.Main conclusionsLandscape palaeolimnological analyses of varied Ecuadorean Andean lakes demonstrate both environmental and spatial controls on diatom metacommunities. The multi‐faceted ecological control of the altitudinal gradient on both historic and contemporary diatom assemblages suggests species sorting and dispersal constraints operating at centennial time‐scale. Although a few individual lakes show substantive change between the 1850s and today, the majority of lakes do not, and the analysis suggests the resilience of lakes at a regional scale. We emphasize the potential of diatom palaeolimnological approaches in biogeography to test ecologically relevant hypotheses of the mechanisms driving recent limnological change in high‐elevation tropical lakes.

海拔变化对凤阳山针阔混交林地土壤微生物群落的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 海拔变化对凤阳山针阔混交林地土壤微生物群落的影响 DOI: 10.5846/stxb201708211503 作者: 作者单位: 南方现代林业协同创新中心，江苏省水土保持与生态修复重点实验室，南京林业大学林学院,南方现代林业协同创新中心，江苏省水土保持与生态修复重点实验室,南方现代林业协同创新中心，江苏省水土保持与生态修复重点实验室，南京林业大学林学院,南方现代林业协同创新中心，江苏省水土保持与生态修复重点实验室，南京林业大学林学院,南方现代林业协同创新中心，江苏省水土保持与生态修复重点实验室,浙江凤阳山—百山祖国家级自然保护区凤阳山管理处,浙江凤阳山—百山祖国家级自然保护区凤阳山管理处,浙江凤阳山—百山祖国家级自然保护区凤阳山管理处 作者简介: 通讯作者: 中图分类号: 基金项目: 林业科学技术推广项目[2015]17号；江苏省高校自然科学研究重大项目（15KJA220004）；江苏省高校研究生科研创新项目（KYZZ16-0323） Effects of altitude on soil microbial community in Fengyang Mountain coniferous and broad-leaved forest Author: Affiliation: Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration,Co-Innovation Center for the Sustainable Forestry in Southern China,College of Forestry,Nanjing Forestry University,Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration,Co-Innovation Center for the Sustainable Forestry in Southern China,College of Forestry,Nanjing Forestry University,Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration,Co-Innovation Center for the Sustainable Forestry in Southern China,College of Forestry,Nanjing Forestry University,Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration,Co-Innovation Center for the Sustainable Forestry in Southern China,College of Forestry,Nanjing Forestry University,Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration,Co-Innovation Center for the Sustainable Forestry in Southern China,College of Forestry,Nanjing Forestry University,The Fengyangshan Management Office of Fengyang Mountain-Baishanzu National Nature Reserve in Zhejiang Province,Longquan,China,The Fengyangshan Management Office of Fengyang Mountain-Baishanzu National Nature Reserve in Zhejiang Province,Longquan,China,The Fengyangshan Management Office of Fengyang Mountain-Baishanzu National Nature Reserve in Zhejiang Province,Longquan,China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:风阳山自然保护区是森林生态类型自然保护区，针阔混交林是保护区内的重要森林类型。为明确海拔变化对高山针阔混交林地土壤微生物群落的影响及初步影响机理，了解气候变暖后典型林分土壤微生物群落结构的变化。以黄山松在凤阳山的分布范围800-1800 m为准，选取900、1100、1300、1500、1700 m 5个海拔梯度，在每个海拔梯度的阳坡内选取排水较好、坡度较缓、长势适中的3个标准样地（20 m×20 m），于2016年8月用蛇形法于每块样地取样，用冰盒带回实验室，测定土壤理化性质及微生物群落。采用磷脂脂肪酸（PLFA）图谱分析确定土壤微生物群落组成及其丰度，同时对土壤微生物群落组成进行非度量多维标度（NMDS）排序，对土壤微生物群落组成结构进行分析。结果表明：随着海拔升高，针阔混交林样地内植物种类组成有所变化。土壤养分含量呈先升高后降低的趋势，差异性显著（P < 0.05）；土壤微生物群落丰度之间存在显著差异，革兰氏阴性细菌丰度在高海拔处较大；土壤微生物群落组成非度量多维标度（NMDS）排序显示，随海拔升高，土壤微生物群落组成发生明显改变，可以分为三个类群，各海拔土壤微生物群落结构在两个NMDS轴上均呈现出显著差异（P < 0.05）。通过对土壤微生物群落丰度与土壤理化性质的冗余分析（RDA），发现土壤pH、容重、含水量、及有效磷含量对对土壤微生物群落丰度有不同程度的影响，土壤革兰氏阳性细菌、放线菌丰度与各土壤因子之间均有显著相关关系；革兰氏阴性细菌受土壤含水量及有效磷的含量影响较大；真菌丰度与土壤pH及有机碳含量之间存在相关关系；厌氧菌及16：1ω5c丰度与土壤因子间相关性较弱。海拔变化所引起的土壤理化性质的改变，是影响土壤微生物群落丰度的因素；6个微生物群落对海拔的适应程度是不同的，革兰氏阴性细菌对高海拔的低温环境适应能力较强。 Abstract:Fengyang Mountain Nature Reserve is a natural reserve of forest ecological type, coniferous and broad-leaved forest is an important forest type in the nature reserve. To understand the impacts of altitude change on soil microbial communities and soil physicochemical properties, we explored the physicochemical properties and microbial community composition of alpine coniferous and broad-leaved forest, the main vegetation types of Fengyang Mountain. Based on the distribution range of Pinus taiwanensis in Fengyang mountain, 900 m, 1100 m, 1300 m, 1500 m, and 1700 m were selected as five altitudinal gradients, and three standard plots were set at each elevation gradient (20 m×20 m), which were sampled in August 2016. Using phospholipid fatty acids (PLFA) spectrum analysis to determine the composition and abundance of soil microbial community, and the soil microbial community composition of non-metric multidimensional scaling (NMDS) ordination, on soil microbial community structure was analyzed. The results showed that the composition of plant species in coniferous and broad-leaved forests has changed. The soil nutrient content first increased and then decreased, and was significantly reduced at high altitudes (P < 0.05), and there were significant differences between soil microbial community abundance. Gram-negative bacterial abundance was higher at high altitudes. NMDS analysis show that the increase in altitude changed the soil microbial community, which can be divided into three groups. Soil microbial community structure at different altitudes showed significant differences in the two NMDS axes (P < 0.05). The redundancy analysis showed that soil bulk density, water content, and pH effected soil microbial composition in different ways:soil gram-positive bacterial and antino bacterial abundance were significantly influenced by the soil properties we studied, whereas soil water content and available phosphorus content mainly affected soil gram-negative bacterial abundance, and the abundance of anaerobic bacteria and 16:1ω5c was weakly correlated with soil properties. The change in soil physicochemical properties caused by altitude was the main factor affecting soil microbial community abundance. The adaptability of six microbial communities to altitude was different; and the gram-negative bacteria have the strongest adaptability to high altitude and low temperature environment. 参考文献 相似文献 引证文献

Carbon Mineralization in Peatlands: Does the Soil Microbial Community Composition Matter?

Peat from four geographically separated peatlands (up to 1,500 km apart) with distinct vegetation across North America was sterilized and inoculated with microbial consortia from either the home site or from the other sites. This reciprocal inoculation microcosm experiment examined how different microbial communities adapted to various peat substrates and how this in turn influenced C-mineralization patterns. The experimental approach allows distinctions to be made as to whether microbial community structure, peat properties, or imposed environmental conditions are primary drivers of peat C mineralization. Two additional inocula collected from other freshwater environments (industrially polluted harbor and lake sediments) were also added to each peat type to investigate the response of clearly disparate microbial communities. We hypothesized that the peat properties, such as substrate quality and physical structure, would dictate microbial community composition and activity, thus inoculations from different sites into the same peat soil would lead to the establishment of very similar microbial communities both phylogenetically and functionally. Post-incubation, the bacterial communities in each site converged towards a similar community regardless of the inoculum source, with the exception of peat inoculated with polluted harbor sediment. Inoculum type had no effect on C mineralization rates compared with controls, except for the two disparate inocula, which had lower rates in all peat types. Variation in microbial community structure measured as nonmetric multidimensional scaling axes scores or richness did not correlate significantly with microbial activity. Overall, these findings suggest that abiotic variables (e.g., pH, aeration, moisture content, and temperature) are the dominant control on peatland microbial activity and community composition, and in natural peatlands the microbial community can quickly adapt to future environmental change.

Contributions of landscape trees in public housing estates to urban biodiversity in Hong Kong

Public housing estates (PHEs) in Hong Kong, accommodating 3.3 million of the 7-million population, have generous landscape planting in their grounds. The independent tree management regime generates a tree stock that deviates from the general urban-tree population. This study evaluated species composition, floristic diversity, importance value, and spatial distribution of trees in 102 PHEs (half of the total) occupying 8.31km2 (territory land area of 1104km2), assessed their contribution to urban biodiversity, and developed a species selection strategy to enrich urban biodiversity. 48,823 trees belonged to 232 species, 151 genera and 59 families. Natives contributed 69 species and 10,837 trees. Species profile was skewed toward exotic species and trees. The species were divided into six frequency groups. The signature group had 45 species each with >200 trees. The dominant, common and occasional groups had 20, 26 and 48 species, respectively. 59 species in the rare group and 34 in the solitary group denoted changing and diverse species selections, respectively. Nonmetric Multidimensional Scaling (NMDS) found that species distribution in PHEs was strongly associated with species diversity, estate area and estate age. However, district and region were not correlated with NMDS. Some 98 species were significantly correlated (Spearman) with one or both NMDS axes. Species groups were analyzed to inform a species selection strategy to improve future planting program and enrich urban biodiversity. The methods and findings could be applied to south-China and other cities to rationalize urban-forest programs with the help of objective research data.

Resilience against exotic species invasion in a tropical montane forest

AbstractQuestionHow do canopy disturbance and soil properties structure vascular plant community species composition and resilience to encroachment by exotic species in a tropical montane wet forest?LocationHawai'i Experimental Tropical Forest (HETF), a tropical montane wet forest, on Mauna Kea, Hawai'i Island, Hawai'i, USA.MethodsPrevious studies employing airborne LiDAR were used to define three zones across an elevation gradient from 900 to 1500 m. Within each zone, a ~1000‐m block transect was selected to cross two different volcanic substrates: one derived from surface lava and one derived from thick ash deposits. Non‐metric multidimensional scaling (NMS) scores of vegetation data were related to independently‐derived environmental NMS scores and spatial location with generalized additive models (GAM).ResultsVascular plant species composition in all elevation zones consists of three NMS axes, which are best modelled by one of three possible environmental NMS axes or by location. The first NMS axis of species composition in the lowest elevation zone (40% variance explained (VE)) is a function of location on volcanic substrates (61% deviance explained (DE)). The second lowest elevation axis (27% VE) is a function of unexplained spatial heterogeneity (31% DE). The third lowest elevation NMS axis (24% VE) is a function of the spatial mosaic of canopy disturbance (16% DE). In the middle elevation zone, species composition most strongly relates to the interaction between volcanic substrate and the condition of the soil surface for all three NMS axes (41%, 27%, 24% VE; 70%, 16%, 24% DE). The primary axis of species composition in the highest elevation zone (41% VE) corresponds with substrate and soil condition (55% DE) but the second and third axes of species composition (27% and 25% VE) relate to canopy dieback disturbance (36%, 14% DE). Counts of exotic species and 0–2 m height class native tree species respond to the type of volcanic substrate and soil surface condition in all three elevation zones. Lava‐derived substrates have a higher incidence of exotic species and less native tree regeneration; whereas ash‐derived substrates have higher numbers of native tree species regenerating and many fewer exotic species.DiscussionThe tropical montane forests on Mauna Kea reflect a native‐dominated plant community response to disturbance on both lava‐ and ash‐derived volcanic substrates, and a higher propensity for exotic species to occur on the lava‐derived substrate. Native plant communities on ash‐derived soils may have higher resilience to exotic invasion than communities on lava‐derived substrates. Our results indicate resource managers should explicitly account for variation in soils and substrate type when prioritizing, implementing and monitoring management interventions to foster native plant assemblages and control the spread of exotic and invasive species.

The effect of anthropic pressures and elevation on the large and medium-sized terrestrial mammals of the subtropical mountain forests (Yungas) of NW Argentina

We conducted a 55-day long camera-trap survey in the Yungas subtropical forest in NW Argentina, to assess the effect of human accessibility, conservation status of the area, domestic animals and elevation on the diversity and composition of the large and medium-sized native terrestrial mammal assemblage. We deployed 24 camera-trap stations at distances of ∼2km from each other. The study area is covered by continuous forest and has its center in the small community of Acambuco, in the Acambuco Provincial Reserve. The main economic activity in the area is oil/gas exploitation. Local residents raise cattle, hunt and use timber and non-timber forest products. The human impact was indirectly measured with an accessibility cost model. We used a multiple regression ANCOVA to assess the effect of elevation (range: 628–1170masl), accessibility, protection status (reserve vs not) and frequency of records of domestic animals on the native mammal species richness and on a nonmetric multidimensional scaling (NMDS) ordination based on the frequency of records of the native mammals recorded at >3 camera-trap stations. We recorded 15 species of native mammals. Native mammal species richness decreased with elevation. Elevation was correlated with NMDS axes. Other predictive variables had no effect on species richness or the NMDS ordination, probably as a result of the relatively narrow range of conditions assessed in this study. The effect of elevation on mammal assemblages should be considered in landscape planning processes aimed at promoting biodiversity conservation.

Environmental Characteristics accounting for Odonate Assemblages in Rural Reservoir Ponds in Japan

To clarify the effect of environmental factors on odonate assemblages in rural reservoir ponds, we surveyed the odonate adults (Zygoptera and Anisoptera) in 70 study ponds in Ibaraki Prefecture, Japan, during three sampling periods in 2005. Cluster analysis, indicator species analysis (INSPAN), and non-metric multidimensional scaling (NMDS) were used in combination to determine the relationship between odonate assemblages and environmental variables, i.e., biotic, physicochemical, and regional variables (the types of land use surrounding the ponds). A total of 41 odonate species were recorded in the study ponds, and 24 of them, excluding rare species, were used for each analysis. The study ponds were classified into six groups, and significant indicator species were selected from four of these groups. Examination of the correlation between each environmental variable and NMDS axes 1 and 2 revealed the profound effects of the presence of forest, paddy field, or open area around the ponds on the indicator species composition of each group. It was also revealed that the aquatic vegetation and forests around the ponds provide desirable conditions for the odonates and, in contrast, concrete revetment has a detrimental effect. These results suggest that the recent decrease of forests around ponds and the reconstruction with concrete revetment will have a negative effect on the odonate assemblages in ponds.

Bat community structure within riparian areas of northwestern Georgia, USA

Although it is well known that bats commonly forage in riparian areas, which provide water resources and insect concentrations, the role that the physical structure of riparian areas plays in influencing local bat communities is less certain. In 2000–2002, we used acoustic monitoring to determine bat species presence at 338 riparian sites in northwestern Georgia, USA. We used a 2-dimensional nonmetric multidimensional scaling (NMDS) ordination to assess how separations among species were partially associated with riparian conditions. Our NMDS analysis found some degree of habitat partitioning among bat species occurring in northwestern Georgia and was dictated in part by riparian condition. Myotis grisescens and M. septentrionalis were associated with low-elevation lotic waterways, whereas M. lucifugus, Lasiurus borealis, and Eptesicus fuscus were associated with high-elevation lentic waterways with sparse canopy cover. However, riparian conditions had weak relations with NMDS axes, possibly resulting in coincidental associations in some cases. Regression tree analysis indicated that higher bat species richness was associated with apparently uncommon small, high-elevation waterways with sparse canopy cover as well as larger streams and rivers that had wetlands adjacent to them. Including high-elevation waterways with existing management recommendations for endangered M. grisescens foraging areas (large, low-elevation streams and rivers) will be the most effective conservation strategy to benefit the most bat species in northwestern Georgia and probably elsewhere in the southern Appalachians.

Effects of soil physical characteristics and biotic interferences on the herbaceous community composition and species diversity on the campus of Banaras Hindu University, India

Soil, water and species diversity relationships are central components of the vegetation ecology. In this connection, the present study was performed on the three sites within the campus of Banaras Hindu University of India, to relate herbaceous species diversity to soil physical characteristic and the intensity of biotic interferences. At each site, three, 10 m × 10 m plots were randomly established and within each plot, four quadrats each 50 cm × 50 cm were randomly placed for sampling. For each quadrat, number of individuals and their herbage cover were recorded by species. Soil physical characteristics (soil moisture, water-holding capacity, soil porosity and bulk density), elements of biotic interferences and α-diversity and its components were determined for each plot. The plots were ordinated by Non-metric Multidimensional Scaling (NMS) using Importance Value Indices of the component species. Results showed that the selected locations differed in terms of soil moisture and species diversity parameters due to differences in biotic interferences. NMS ordination yielded three groups corresponding to the three communities experiencing different intensity of land use. NMS axes were substantially related to the soil and herbaceous diversity parameters and suggested that the elements of soil physical characteristics, intensity of biotic interferences and regional herbaceous species pool had profound effect on the organization and determination of herbaceous floristic composition. Further, the sample locations exhibiting greater soil moisture, water-holding capacity, soil porosity and lesser soil bulk density harboured greater herbaceous diversity. A negative relationship between indices of species diversity and soil bulk density revealed that the dry and compact soils due to greater biotic pressure contributed to the loss of species diversity. Reduction in livestock numbers, grazing pressure and soil bulk density could be helpful in the promotion of soil quality and species diversity.

Vegetative Community Compositional Gradients of Tropical Hardwood Hammocks along the Florida Keys

ABSTRACTTropical hardwood hammocks, among the rarest and most threatened vegetative communities in the United States, occur throughout the 225‐km Florida Keys archipelago as it extends toward the Caribbean from the southeast tip of peninsular Florida. Compounding their critical conservation status, tropical hardwood hammocks and the dynamics that support their peculiar species diversity in the region are poorly understood. The goal of this study was to explore the dynamics of the species compositional gradient of the hammocks along the Florida Keys, and to identify significant ecological units within the gradient. The primary data for this research were assembled from the Institute for Regional Conservation's floristic database of South Florida. We were able to extract presence/absence data for 295 species from comprehensive surveys of 23 study sites. Nonmetric multidimensional scaling was used to deconstruct the compositional trends into a reduced ordination space. Cluster analysis was subsequently used to identify discrete ecological units. Additionally, we used vector fitting to interpret the significant correlated ancillary variables. Our main results were three well‐fitted nonmetric multidimensional scaling axes with three nonoverlapping ecological units. Of the ancillary variables, latitude, longitude, percent composition from biogeographical regions, richness, and area were correlated to the nonmetric multidimensional scaling results. These results increase our understanding of the community structure of the hammocks along the Florida Keys, and can contribute to increasing our ability to adequately protect and restore tropical hardwood hammocks and other similar tropical dry forest communities throughout the Caribbean.

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

AbstractQuestions: 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.

Elevation gradients and lizard assemblage structure in the Bonneville Basin, western USA

We analyzed lizard assemblage structure as a function of elevation in the Bonneville Basin region of the Great Basin Desert using data from visual surveys performed between 2000 and 2003. A total of 1221 lizard observations were recorded, representing eight of the nine species known to occur in the Bonneville Basin. Individual species response curves showed Gaussian and truncated Gaussian distributions for most taxa, and most species demonstrated a nonrandom dispersion of occurrences along the elevation gradient. Nonmetric multidimensional scaling (NMS) revealed hierarchical structuring of lizard species, and strong correlation of NMS axes with elevation provided evidence of uniform lizard community assembly with respect to elevation throughout the study region. Species richness averaged between 2 and 3 across surveys and specific species pairs were frequently associated with each other. Collectively our analyses provide insight into the possible roles of history and habitat heterogeneity in the structuring of a depauperate lizard fauna at the mesoscale.

Influence of clearcut logging, flow duration, and season on emergent aquatic insects in headwater streams of the Central Oregon Coast Range

We measured the effects of timber-harvest condition (clearcut and forested) and flow duration (perennial and intermittent) on emergent aquatic insect assemblages at 20 headwater streams in the Central Oregon Coast Range. Clearcut streams had been logged to the stream banks within 2 y prior to the start of our study. Adult aquatic insects were sampled from a 40-m reach at each study stream in 3 seasons: summer, autumn, and spring. Emergent insects were strong indicators of harvest condition and, regardless of flow duration or season, more aquatic insects emerged from streams in clearcut catchments than in forested catchments. Plecoptera had higher emergence rates from intermittent streams than from perennial streams in spring. Functional feeding group composition was not apparently affected by harvest condition or flow duration. Taxon richness was slightly higher at clearcut than at forested streams, primarily because of the occurrence of rare taxa at clearcut streams. Nonmetric multidimensional scaling (NMS) ordination of emergent aquatic insect assemblages showed community patterns that varied by season and harvest condition, but little by flow duration. Stream canopy % cover, stand age, logging debris (% slash), and substrate composition differed between clearcut and forested streams and were strongly correlated with NMS axes. Taxa that responded to conditions created by logging, such as % slash or canopy opening, contributed to differences in assemblages between headwater streams flowing through clearcut and forested catchments.

Mapping the floristic continuum: Ordination space position estimated from imaging spectroscopy

AbstractObjective: To present a non‐classificatory technique of map representation of compositional patterns of vegetation as no two plant species assemblages are completely alike and gradations often occur. Variation is depicted as continuous fields instead of classes.Location: Murnauer Moos, Bavaria. Methods: The study combined vegetation ecology and remote sensing methods. The gradual representation of compositional patterns was based on techniques of ordination and regression, instead of mapping class fractions. The floristic field data were collected in relevés and subjected to three‐dimensional non‐metric multidimensional scaling (NMS). The reflectance information corresponding to plots was gathered from remotely sensed imagery with a high spectral resolution. Reflectance values in numerous wavelengths were related to NMS axes scores by partial least squares regression analysis. The regression equations were applied to the imagery and yielded three grey‐scale images, one for each ordination axis. These three images were transformed into a red, green, and blue colour map with a specific colour for each position in the ordination space. Similar colours corresponded to similar species compositions.Results: Compositional variation was mapped accurately (R2= 0.79), using continuous fields. The results took account of various types of stand transitions and of heterogeneities within stands. The map representation featured relatively homogeneous stands and abrupt transitions between stands as well as within‐stand heterogeneity and gradual transitions.Conclusions: The use of NMS in combination with imaging spectroscopy proved to be an expedient approach for non‐classificatory map representations of compositional patterns. Ordination is efficiently extended into the geographic domain. The approach in abandoning pre‐defined plant communities is able to reconcile mapping practice and complex reality.

Mapping the floristic continuum: Ordination space position estimated from imaging spectroscopy

Objective: To present a non-classificatory technique of map representation of compositional patterns of vegetation as no two plant species assemblages are completely alike and gradations often occur. Variation is depicted as continuous fields instead of classes. Location: Murnauer Moos, Bavaria. Methods: The study combined vegetation ecology and remote sensing methods. The gradual representation of compositional patterns was based on techniques of ordination and regression, instead of mapping class fractions. The floristic field data were collected in relevés and subjected to three-dimensional non-metric multidimensional scaling (NMS). The reflectance information corresponding to plots was gathered from remotely sensed imagery with a high spectral resolution. Reflectance values in numerous wavelengths were related to NMS axes scores by partial least squares regression analysis. The regression equations were applied to the imagery and yielded three grey-scale images, one for each ordination axis. These three images were transformed into a red, green, and blue colour map with a specific colour for each position in the ordination space. Similar colours corresponded to similar species compositions. Results: Compositional variation was mapped accurately (R2= 0.79), using continuous fields. The results took account of various types of stand transitions and of heterogeneities within stands. The map representation featured relatively homogeneous stands and abrupt transitions between stands as well as within-stand heterogeneity and gradual transitions. Conclusions: The use of NMS in combination with imaging spectroscopy proved to be an expedient approach for non-classificatory map representations of compositional patterns. Ordination is efficiently extended into the geographic domain. The approach in abandoning pre-defined plant communities is able to reconcile mapping practice and complex reality.