Habitat Associations and Community Structure of Dipterocarps in Response to Environment and Soil Conditions in Brunei Darussalam,Northwest Borneo

Plant habitat associations are well documented in Bornean lowland tropical forests, but few studies contrast the prevalence of associations across sites. We examined habitat associations and community composition of Dipterocarpaceae trees in two contrasting Bornean lowland mixed dipterocarp forests separated by approximately 100 km: Andulau (uniform topography, lower altitudinal range, sandy soils) and Belalong (highly dissected topography, higher altitudinal range, clay‐rich soils). Dipterocarpaceae trees ≥ 1 cm diameter at breast height (dbh) were censused in 20‐m wide belt transects established along topographic gradients at each site. Dipterocarp density, evenness, species richness, and diversity were significantly higher at Andulau than Belalong. Significant site associations (with either Andulau or Belalong) were detected for 19 (52%) of the 37 dipterocarp species tested. Dipterocarpaceae community composition at Belalong correlated with soil nutrient concentrations as well as measures of vegetation and topographic structure, but community composition at Andulau correlated with fewer habitat variables. Within each site, dipterocarp density, species richness, and diversity were consistently higher on ridges than in slopes and valleys. Significant within‐site associations to topographic habitats were less common at Andulau (10% of species tested) than at Belalong (15%). We conclude that edaphic and other environmental factors influence dipterocarp community composition at a local scale, and are more important drivers of community structure in the more variable environment at Belalong. Species richness and diversity of dipterocarps on small plots, however, were higher at Andulau, suggesting that factors other than environmental heterogeneity contribute to contrasts in dipterocarp tree species richness at small scales.     

灰楸不同流域种质变异与多样性研究

通过对灰楸4个流域的137份种质资源的1年生嫁接苗10个表型性状的变异与多样性分析,结果表明:10个表型性状在流域间、流域内均达极显著差异。流域间10个表型性状平均变异系数、遗传变异系数分别为15.81%、29.08%;遗传方差分量都约在70%及以上,说明10个表型性状的差异主要为遗传因素,从流域内变异看,叶部指标和皮孔数在泾河流域和汾河流域变异较大,生长指标和比叶重、含水量、在渭河流域和嘉陵江流域变异较大。总的Shannon-Weaver指数为6.995,趋势是嘉陵江流域>泾河流域>汾河流域>渭河流域。基于表型性状的聚类分析把4个流域的种质在遗传距离为3.65处分为3类。第1类包含来自渭河流域的28份种质和嘉陵江流域的46份种质,第2类是汾河流域的24份种质,第3类是来自泾河流域的39份种质,叶长、叶宽、叶柄长、叶面积、生长量5个表型性状变异随海拔的升高具有一定的连续性。     

Biostratigraphie des conodontesdu Muschelkalk supérieur luxembourgeois

Biostratigraphic scale of conodonts established inthe germanic basin is found in Luxemburg. The repartition of associations allows to determine six zones which can be compared to those of neighbouring areas.     

Fine-scale spatial organization of tallgrass prairie vegetation along a topographic gradient

Fine-scale spatial patterns of native tallgrass prairie vegetation were studied on Konza Prairie, Kansas, USA. Three sites, upland, slope, and lowland, were sampled in an ungrazed watershed. Presence of vascular plant species was recorded in two 25.6 m long transects of contiguous 5×5 cm micro-quadrats on each topographic position. Spatial patterns of species and functional groups were analyzed by information theory models ofJuhász-Nagy. Within-community variability of coexistence was expressed by the diversity and spatial dependence of local species combinations. Considerable diversity in the local coexistence of species was found on each site. Upland and hillside communities were richer and more diverse in species combinations than lowland. Spatial scale effected coexistence relationships. The maxima of information theory estimates varied between 15 and 30 cm. There was no trend in the variation of characteristic scales along the topographical gradient. Above 10 m, all sites tended to be homogeneous. The analysis of spatial associations revealed that variability in the local coexistence of species was strongly constrained in all topographic positions. Overall spatial association of species was the lowest on lowland. The characteristic scales of maximum association were between 1.2 m and 3 m at all sites. The maxima of information theory estimates for the functional group-based data appeared at smaller plot sizes than for the species based analyses. Only weak spatial associations were detected among the functional groups indicating that individuals of functional groups coexist well at small scales, and form combinations close to random expectations. The length of transects did not effect the relative associations. Strong positive correlations were found between the number of components (species or functional groups) and the maxima, of information theory models suggesting that richness is a good predictor of within-community coexistence relations. However, there was no relationship between richness and the characteristic scales of community patterns.     

Phylogeography of the Mekong mud snake (Enhydris subtaeniata): the biogeographic importance of dynamic river drainages and fluctuating sea levels for semiaquatic taxa in Indochina

During the Cenozoic, Southeast Asia was profoundly affected by plate tectonic events, dynamic river systems, fluctuating sea levels, shifting coastlines, and climatic variation, which have influenced the ecological and evolutionary trajectories of the Southeast Asian flora and fauna. We examined the role of these paleogeographic factors on shaping phylogeographic patterns focusing on a species of semiaquatic snake, Enhydris subtaeniata (Serpentes: Homalopsidae) using sequence data from three mitochondrial fragments (cytochrome b, ND4, and ATPase-2785 bp). We sampled E. subtaeniata from seven locations in three river drainage basins that encompassed most of this species' range. Genetic diversities were typically low within locations but high across locations. Moreover, each location had a unique suite of haplotypes not shared among locations, and pairwise φ(ST) values (0.713-0.998) were highly significant between all location pairs. Relationships among phylogroups were well resolved and analysis of molecular variance (AMOVA) revealed strong geographical partitioning of genetic variance among the three river drainage basins surveyed. The genetic differences observed among the populations of E. subtaeniata were likely shaped by the Quaternary landscapes of Indochina and the Sunda Shelf. Historically, the middle and lower Mekong consisted of strongly dissected river valleys separated by low mountain ranges and much of the Sunda Shelf consisted of lowland river valleys that served to connect faunas associated with major regional rivers. It is thus likely that the contemporary genetic patterns observed among populations of E. subtaeniata are the result of their histories in a complex terrain that created abundant opportunities for genetic isolation and divergence yet also provided lowland connections across now drowned river valleys.     

Geomorphology variables predict fish assemblages for forested and endorheic rivers of two continents

Stream fishes are restricted to specific environments with appropriate habitats for feeding and reproduction. Interactions between streams and surrounding landscapes influence the availability and type of fish habitat, nutrient concentrations, suspended solids, and substrate composition. Valley width and gradient are geomorphological variables that influence the frequency and intensity that a stream interacts with the surrounding landscape. For example, in constrained valleys, canyon walls are steeply sloped and valleys are narrow, limiting the movement of water into riparian zones. Wide valleys have long, flat floodplains that are inundated with high discharge. We tested for differences in fish assemblages with geomorphology variation among stream sites. We selected rivers in similar forested and endorheic ecoregion types of the United States and Mongolia. Sites where we collected were defined as geomorphologically unique river segments (i.e., functional process zones; FPZs) using an automated ArcGIS‐based tool. This tool extracts geomorphic variables at the valley and catchment scales and uses them to cluster stream segments based on their similarity. We collected a representative fish sample from replicates of FPZs. Then, we used constrained ordinations to determine whether river geomorphology could predict fish assemblage variation. Our constrained ordination approach using geomorphology to predict fish assemblages resulted in significance using fish taxonomy and traits in several watersheds. The watersheds where constrained ordinations were not successful were next analyzed with unconstrained ordinations to examine patterns among fish taxonomy and traits with geomorphology variables. Common geomorphology variables as predictors for taxonomic fish assemblages were river gradient, valley width, and valley slope. Significant geomorphology predictors of functional traits were valley width‐to‐floor width ratio, elevation, gradient, and channel sinuosity. These results provide evidence that fish assemblages respond similarly and strongly to geomorphic variables on two continents.     

Transferrins,haptoglobins, and ceruloplasmins among tribal groups of Madagascar

Transferrin phenotypes of 403 Malagasy were determined by autoradiography after electrophoresis of plasma or serum. Three phenotypes, Tf C, Tf CD, and Tf D, were found. The frequency of Tf^D was 0.051 in the total sample, 0.041 in tribes of the Madagascar plateau, and 0.075 in tribes of the coastal and lowland regions. Haptoglobin phenotypes of 402 Malagasy were determined. The frequency of Hp¹ was 0.41 in the total sample, 0.38 in tribes of the plateau, and 0.49 in coastal-lowland tribes. There is a significant difference in the frequency of Hp¹ between the tribes of the plateau and those of the coastal and lowland regions. This confirms earlier observations of significant differences in frequencies of haptoglobins and hemoglobin S. Plasma or serum samples from 405 Malagasy were examined by electrophoresis to determine ceruloplasmin phenotypes. Seven distinct ceruloplasmin bands were observed. These were A, B, Galveston, Bridgeport, New Haven, Tananarive, and X, the last two described for the first time. Ten different phenotypes composed of one or two of the bands were observed. The frequency of the allele for ceruloplasmin B (CpB) was 0.78 in the total sample, 0.73 in tribes of the plateau, and 0.92 in coastal and lowland tribes. There is a significant difference in the frequency of this allele in the two major tribal groups, and this provides additional evidence of genetic differences between the peoples of the plateau and those of the coast and lowland regions of Madagascar.     

Tree Diversity,Forest Structure and Productivity along Altitudinal and Topographical Gradients in a Species-Rich Ecuadorian Montane Rain Forest

We studied the spatial heterogeneity of tree diversity, and of forest structure and productivity in a highly diverse tropical mountain area in southern Ecuador with the aim of understanding the causes of the large variation in these parameters. Two major environmental gradients, elevation and topography, representing a broad range of climatic and edaphic site conditions, were analyzed. We found the highest species richness of trees in valleys <2100 m. Valleys showed highest values of basal area, leaf area index and tree basal area increment as well. Tree diversity also increased from ridges to valleys, while canopy openness decreased. Significant relationships existed between tree diversity and soil parameters (pH, total contents of Mg, K, Ca, N and P), and between diversity and the spatial variability of pH and Ca and Mg contents suggesting a dependence of tree diversity on both absolute levels and on the small-scale heterogeneity of soil nutrient availability. Tree diversity and basal area increment were positively correlated, partly because both are similarly affected by soil conditions. We conclude that the extraordinarily high tree species richness in the area is primarily caused by three factors: (1) the existence of steep altitudinal and topographic gradients in a rather limited area creating a small-scale mosaic of edaphically different habitats; (2) the intermingling of Amazonian lowland plant species, that reach their upper distribution limits, and of montane forest species; and (3) the geographical position of the study area between the humid eastern Andean slope and the dry interandean forests of South Ecuador.     

中国西藏种子植物区系新资料

本文报道了采自西藏喜马拉雅南坡的8个中国种子植物新记录种以及1个西藏新记录属。前者分别是吉隆牛奶菜(Marsdenia roylei)、塔基棕榈(Trachycarpus takil)、喀西蜂斗草(Sonerila khasiana)、旋花锡生藤(Cissampelos convolvulacea)、吉隆角盘兰(Herminium edgeworthii)、尼泊尔西番莲(Passiflora napalensis)、椭穗姜花(Hedychium ellipticum)和藏南象牙参(Roscoea brandisii); 1个西藏新记录属为箭药藤属(Belostemma) (箭药藤 Belostemma hirsutum)。凭证标本存放于中国科学院西双版纳热带植物园标本馆(HITBC)和西藏自治区高原生物研究所标本室(XZ)。     

Investigating the relationship between raw milk bacterial composition, as described by intergenic transcribed spacer–PCR fingerprinting, and pasture altitude

Aims:  To assess the bacterial biodiversity level in bovine raw milk used to produce Fontina, a Protected Designation of Origin cheese manufactured at high-altitude pastures and in valleys of Valle d'Aosta region (North-western Italian Alps) without any starters. To study the relation between microbial composition and pasture altitude, in order to distinguish high-altitude milk against valley and lowland milk.
Methods and Results:  The microflora from milks sampled at different alpine pasture, valley and lowland farms were fingerprinted by PCR of the 16S–23S intergenic transcribed spacers (ITS-PCR). The resulting band patterns were analysed by generalized multivariate statistical techniques to handle discrete (band presence–absence) and continuous (altitude) information. The fingerprints featured numerous bands and marked variability indicating complex, differentiated bacterial communities. Alpine pasture milks were distinguished from lowland ones by cluster analysis, while this technique less clearly discriminated alpine pasture and valley samples. Generalized principal component analysis and clustering-after-ordination enabled a more effective distinction of alpine pasture, valley and lowland samples.
Conclusions:  Alpine raw milks for Fontina production contain highly diverse bacterial communities, the composition of which is related to the altitude of the pasture where milk was produced.
Significance and Impact of the Study:  This research may provide analytical support to the important issue represented by the authentication of the geographical origin of alpine milk productions.     

Biological diversification in a complex region: a spatial analysis of faunistic diversity and biogeography of the Andes of Colombia

Aim Understanding large‐scale patterns of beta diversity and endemism is essential for ecoregional conservation planning. We present a study of spatial patterns of faunal diversification and biogeographical relationships in the Andean region of Colombia. This region has a great geomorphological complexity, as it is formed by several mountain ranges with different geologic origins. We hypothesize that this complexity results in a high turnover in species composition among subregions. Location The Andean region of Colombia, including the Santa Marta and Macarena mountain ranges. Methods The region was divided into subregions, represented by the eastern and western slopes of each of the three Andean cordilleras, the Cauca and Magdalena valley bottoms, and the peripheral mountain ranges of Perijá, Macarena and Sierra Nevada de Santa Marta. Species lists for five animal taxa (rodents, bats, birds, frogs and butterflies) were compiled for each subregion and similarities in species composition were determined by cluster analysis. To explore biogeographical relationships, species were classified into one of four distributional categories: endemic, tropical Andean, Andean‐Central American and wide continental distribution. Results The highest species richness in the region was found in the Pacific and eastern versants of the Andes, and the lowest in the Cauca and Magdalena valley bottoms. Inter‐Andean slopes were intermediate in species richness. However, when species richness was calculated per unit area, the most diverse regions were the Santa Marta and Macarena ranges, the Cauca Valley watershed and the Pacific slope. Although each taxonomic group had a different branching pattern, dendrograms indicated five common subregional clusterings: (1) Perijá‐Sierra Nevada, (2) the Pacific slope, (3) the eastern Andean slope, (4) the Cauca and Magdalena valley bottoms, and (5) the inter‐Andean slopes. Clustering patterns of inter‐Andean slopes varied among taxa. In birds, bats and rodents, grouping was by opposite slopes of the same valley, whereas frogs were grouped by mountain ranges and butterflies by valleys and their respective slopes. Seventy‐five per cent of species in all taxa were found in less than five subregions. The fauna of the Magdalena and Cauca valley bottoms was composed mostly of lowland species with wide geographical distributions, whereas the cordilleran fauna was mostly restricted to the tropical Andes. Main conclusions The western and eastern versants of the Andes have the highest species richness, but are also the largest subregions. On a per unit area basis, the peripheral ranges (Santa Marta and Macarena) are the richest, followed by the western portion of the Andes (the Cauca Valley watershed and the Pacific versant). Clustering patterns in dendrograms suggest two major patterns of differentiation of the Andean fauna: one elevational (lowlands vs. highlands) and one horizontal (among ranges and/or slopes). Biogeographical affinities of the inter‐Andean valley bottoms are with the lowland faunas of tropical America. In contrast, Andean faunas diversified locally, resulting in the evolution of a large number of endemic species, particularly among the less vagile taxa. Three different main branches of Andean fauna can be recognized, one confined to the Pacific, another to the eastern (Amazonian‐Llanos) versant of the Andes, and the third one composed by the inter‐Andean slopes of the Cauca and Magdalena valleys. The identification of five main biogeographical units in the Andean region of Colombia has important implications for the conservation of the regional biota. Conservation initiatives that seek to preserve representative samples of the regional biodiversity should take into account the patterns of diversification described here, and the evolutionary processes that gave rise to these patterns.     

Landscape–Zonal Distribution of Blackflies (Diptera: Simuliidae) in the Ob-Irtysh River Basin (Overview)

The blackfly distribution patterns along the meridional profile for the Ob-Irtysh River basin area have been analyzed with the use of long-term quantitative data. Ninety-six species of nine genera, comprising approximately 60% of the fauna in Siberia and the Far East, are recorded. The spatial pattern formation in the blackfly zonal structures is revealed. There are significant differences between blackfly populations in highland and lowland landscapes. In the highlands, the communities confined to different altitudinal belts are formed. In the lowland of the basin, three community zonal types—steppe, taiga–forest, and tundra—are identified. Significant climatic factors affecting the heterogeneity of the blackflies in the Ob-Irtysh River basin have been estimated.     

Composition and structure of phytoplankton in lowland rivers of the upper Ob basin

Taxonomic composition and structure of the phytoplankton were studied in the lowland rivers of the upper Ob basin: Barnaulka, Bol’shaya Losikha, and lower Inya. It has been shown that the phytoplankton of a large river system in Eurasia, exemplified by the Ob basin, is characterized by spatial heterogeneity in its taxonomic composition.     

Fire survival of lowland tropical rain forest trees in relation to stem diameter and topographic position

The objective of this study was to relate patterns in forest structure, tree species diversity, and tree species composition to stem diameters and topography in unburned, once burned and twice burned lowland dipterocarp rain forests in East Kalimantan, Indonesia. To do this four unburned old growth forests were compared with three forests that burned once (1997/1998) and three forests that burned twice (1982/1983 and 1997/1998). Fire resulted in a strong reduction of climax tree density which was negatively related to tree diameter. However, a disproportionate reduction in small diameter understorey climax tree species occurred only after repeated fires. Climax tree species in both burned forest types were most common in swamps, river valleys and on lower slopes, while their density was much lower on places higher along hillsides. In unburned forest the opposite was observed, with climax tree density increasing steadily from swamp and river valleys to upper slopes and ridges. In contrast to climax trees, pioneer trees were abundant throughout the burned forest, with highest numbers on hill sides and ridges. Our results indicate that both diameter and topographic position of trees strongly affect their fire survival chances in tropical lowland forests.     

Diversity and vertical distribution of epiphytic macrolichens in lowland rain forest and lowland cloud forest of French Guiana

Recent work on bryophyte diversity in lowland forests of northern South America has suggested the existence of a new type of cloud forest, the “tropical lowland cloud forest” (LCF). LCF occurs in river valleys with high air humidity and radiation fog, and is rich in epiphytes. We explored the lichenological characteristics of putative LCF in a lowland area (200–400 m a.s.l.) near Saül, central French Guiana, using macrolichens (including large crustose species) as indicator taxa. We analyzed macrolichen diversity on 16 trees in two 1 ha plots, in LCF and in lowland rain forest without fog (LRF). Sampling efficiency was ca. 80% in both forest types. Canopies of both LRF and LCF were richer in lichen species than understory trunks. Species richness of macrolichens was rather similar in the two forest types but species composition was significantly different. Cyanolichen richness in LCF was ca. 2.5 times higher than in LRF; in contrast, LRF had 4 times more species of green-algal Parmeliaceae. Our study suggests that cyanolichens except for Coccocarpiaceae serve as indicators of LCF. We explain the detected diversity patterns by differences in water availability due to fog precipitation and higher humidity. This is indicated by the higher relative air humidity in the lowland cloud forest, which was >6% higher than in the rain forest.     

Dynamics of agricultural use differentially affect soil properties and crop response in East African wetlands

Agricultural land use changes differentially affect soil fertility and crop production potential of wetlands. We studied East African wetlands with contrasting hydro-geological characteristics (high- and lowland floodplains and valley swamps). Land uses ranged from no use and grazing over crop production in flooded and drained fields to abandonment. We classified the dynamics of wetlands’ conversion into agricultural sites and assessed selected soil fertility attributes associated with land use changes, and their effect on the crop production potential in aerobic and anaerobic soils. A conversion of pristine wetlands, differing in soil physical and chemical attributes, into sites of production tended to negatively affect soil total C and N. Effects were stronger with soil drainage and in the coarse-textured soils of the lowland floodplain and the mid-hill valleys. Mineral P application in drained valleys significantly increased available soil P. Crop response followed these patterns with usually higher biomass accumulation and nutrient uptake in flooded than aerobic soils. Wetlands of fine soil texture in the highlands appeared more resilient than coarse-textured soils, particularly when drained. Enhanced crop performance in flooded soils indicates the possibility for partial recovery of the production potential and the rehabilitation of some wetlands.     

Prediction of plant species distribution in lowland river valleys in Belgium: modelling species response to site conditions

In ecological modelling, limitations in data and their applicability for predictive modelling are more rule than exception. Often modelling has to be performed on sub-optimal data, as explicit and controlled collection of (more) appropriate data would not be feasible. An example of predictive ecological modelling is given with application of generalized additive and generalized linear models fitted to presence–absence records of plant species and site condition data from four nutrient-poor Flemish lowland valleys. Standard regression procedures are used for modelling, although explanatory and response data do not meet all the assumptions implicit in these procedures. Data were non-randomly collected and are spatially autocorrelated; model residuals retain part of that correlation. The scale of most site-condition records does not match the scale of the response variable (species distribution). Hence, interpolated and up-scaled explanatory variables are used. Data are aggregated from distinct phytogeographical regions to allow for generalized models, applicable to a wider population of river valleys in the same region. Nevertheless, ecologically sound models are obtained, which predict well the distribution of most plant species for the Flemish river valleys considered.     

不同沙地生境下黄柳(Salix gordejevii)种群若干数量特征的比较研究

对分布于３种不同沙地生境（半固定沙丘、固定沙丘、丘间低地）黄柳灌丛的个体形态、生长和群体数量特征进行了比较研究,同时测定了灌丛下草本层植物种类组成及频率。结果显示：分布于丘间低地的黄柳灌丛当年枝平均长度增加缓慢,短枝条的比例较高,枝长频度分布（当年枝）峰值偏左,分枝也较多,叶片短而狭,长宽比大;与之相比,分布于半固定沙丘上的灌丛当年枝平均长度增加较快,长枝条比例较高,枝长频度分布趋于正态分布,分枝     

Efficacité de la mémoire associative inhérente à la potentiation post-tétanique

An associative memory is modeled in networks of cells that are assumed to have the short-term plasticity of the neuromuscular junction of the frog. The data relating synaptic transmission efficiency and stimulation frequency for post-tetanic potentiation of the neuromuscular junction are represented by polynomial expansions. Simulation of storage and retrieval demonstrates that functional associative memory is feasible based on this particular synaptic plasticity. Retrieval reaches a maximum efficiency at a delay of three minutes after storage and is lost after about 9 min. The signal to noise ratio of the retrieved pattern drops steadily as additional associations are stored in memory but retrieval appears to be possible with up to four stored associations. Although the data are derived from synapses not normally proposed as a basis for memory functions, the results here will generalize to other synaptic junctions located more centrally that have similar characteristics. This simulation technique allows the efficiency of associative memory based on various types of synaptic plasticity to be evaluated.     

Phytogeographical relations of the Andean dry valleys of Bolivia

Aim The objective of this study is to examine the phytogeographical affinities of the Andean dry valleys of Bolivia in order to contribute to a better understanding of the Andean dry flora's distribution, origin and diversity. Particular emphasis is given to the analysis of the floristic connections of this flora with more austral parts of South America. Location The dry valleys of Bolivia are located in the Andes of the southern half of the country, at elevations between 1300 and 3200 m. Methods An extensive floristic list compiled by the author to evaluate plant diversity in these Andean regions was used as the base for this study. To accomplish this, all recorded genera and species were assigned, respectively, to 11 and 12 phytogeographical elements established previously by the author. Two phytogeographical spectra were thus obtained and analysed. Results At the genus level, the Andean dry valleys of Bolivia are clearly dominated by genera that have widespread distributions (cosmoplitan and subtropical genera). Many of these reached the Andes from the lowland region of the Chaco. At species level, Andean elements constitute more than 60% of the species total, most of which are restricted to the central‐southern Andes. This suggests that Chaco‐related and Andean genera had considerable levels of speciation in these valleys. Many genera and more than half the species have their northernmost distribution in the dry valleys of Bolivia, thereby underlining strong relationships with central‐southern South America (mainly Argentina, Paraguay and southern Brazil). The data supports the belief of the existence, in central‐southern Peru, of a floristic disjunction in dry to arid environments that separates a tropical dry flora north of this limit from a dry subtropical/warm temperate flora south of it. Main conclusions The Andean dry valleys of Bolivia are diverse plant communities with high levels of endemism (c. 18% of the species). The species of this region are more related to those present in central‐southern South America than to the flora of northern South America that ranges southwards to Peru. Many of the species have restricted distributions in the dry Andes of Bolivia and Argentina, and many genera of these dry valleys have their northernmost distribution in Bolivia/southern Peru, too. The data point to high levels of speciation also in the central Andes.