Use of an extensive radio receiver network to document Pacific lamprey (Lampetra tridentata) entrance efficiency at fishways in the Lower Columbia River,USA

We used an extensive network of more than 170 radio receiving stations to document fine-scale passage efficiency of adult anadromous Pacific lamprey at Bonneville and The Dalles Dams in the lower Columbia River in the northwestern U.S.A. Each spring from 1997 to 2000, we released 197–299 lamprey with surgically implanted radio transmitters. Unique transmitter codes and the date and time of reception at each antenna site were downloaded electronically, and initial processing was conducted to eliminate false positive signals. The resulting large Oracle database was analyzed using an ArcView-based coding protocol. Underwater antennas positioned outside the fishway entrances detected lamprey approaches, and antennas positioned immediately inside the entrances indicated successful entries. Entrance efficiency (the number of lamprey that successfully entered a fishway divided by the number that approached that fishway) was compared for different types of entrances (main entrances versus orifice entrances) and entrance locations (powerhouse versus spillway). Lamprey used orifice-type entrances less frequently than main entrances, and passage success was generally low (< 50%) at all entrances to fishways at Bonneville Dam (the lowest dam in the system). Lamprey activity at the entrances was highest at night, and entrance success was significantly higher at The Dalles Dam (the next dam upstream from Bonneville Dam) than at Bonneville Dam. In 1999 and 2000, construction modifications were made to Bonneville Dam spillway entrances, and water velocity at these entrances was reduced at night. Modifications to increase lamprey attachment at the entrances improved lamprey entrance efficiency, but entrance efficiency during reduced velocity tests was not significantly higher than during control conditions.     

Phylogeography of the European brook lamprey (Lampetra planeri) and the European river lamprey (Lampetra fluviatilis) species pair based on mitochondrial data

The European river lamprey Lampetra fluviatilis and the European brook lamprey Lampetra planeri (Block 1784) are classified as a paired species, characterized by notably different life histories but morphological similarities. Previous work has further shown limited genetic differentiation between these two species at the mitochondrial DNA level. Here, we expand on this previous work, which focused on lamprey species from the Iberian Peninsula in the south and mainland Europe in the north, by sequencing three mitochondrial marker regions of Lampetra individuals from five river systems in Ireland and five in southern Italy. Our results corroborate the previously identified pattern of genetic diversity for the species pair. We also show significant genetic differentiation between Irish and mainland European lamprey populations, suggesting another ichthyogeographic district distinct from those previously defined. Finally, our results stress the importance of southern Italian L. planeri populations, which maintain several private alleles and notable genetic diversity.     

集合种群动态对生境毁坏空间异质性的响应

首次将分形几何(Fractal geometry)与元胞自动机(Cellular automata)相结合,研究了破碎化生境中集合种群的空间分布格局动态,以及集合种群动态对生境毁坏空间异质性的响应。研究发现:(1)各个物种种群在生境中的分布具有很好的分形特征,物种的计盒维数(Box dimension)不仅可以很好地反映种群的空间分布结构,也能很好地反映种群动态。(2)如果将空间因素考虑进来的话,生境毁坏的灭绝债务(Time debt)将大于空间隐含模式所模拟的结果。(3)物种灭绝同时存在强物种灭绝和弱物种灭绝。并且只有在生境随机毁坏下,才与空间隐含的模拟结果比较接近,即强物种中将是最强物种率先灭绝。而在边缘毁坏这种比较集中成块的开发方式下,将是较强的物种灭绝。(4)边缘毁坏相对随机毁坏有利于物种,尤其是弱物种的长期续存。     

Perceptual scales of spatial heterogeneity of periphyton for freshwater snails

The hypothesis that individuals recognize their environment as homogeneous when the scales of spatial heterogeneity of resources are smaller than a certain scale, but can distinguish them as patches when they are larger than that scale was tested using freshwater snails ( Physa acuta ) in various distributions in periphyton environments. In a pattern of periphyton distribution in which the size of algal cells was 47 mm, individuals moved significantly more slowly on algal cells than on nonalgal cells. However, in other patterns in which the sizes of algal cells were 23.5 mm and 15.7 mm, the speeds of individuals on algal and nonalgal cells were not significantly different. These results support the hypothesis that individuals use the environment homogeneously when the scales of spatial heterogeneity of resources are smaller than a certain scale, but they can distinguish between patches when the scales are larger.     

Measures of giant panda habitat selection across multiple spatial scales for species conservation

Examining ecological processes across spatial scales is crucial as animals select and use resources at different scales. We carried out field surveys in September 2005, March–September 2006, and April 2007, and used ecological niche factor analysis to determine habitat preferences for the giant panda (Ailuropoda melanoleuca) across 4 spatial scales: daily movement, core range, home range, and seasonal elevational migration. We found that giant pandas prefer conifer forest and mixed forest at higher than average elevation (2,157 m) of study area in the 4 scale models. However, we also observed significant scale differences in habitat selection. The strength of habitat preference increased with scale for the 2 disturbed forests (sparse forest and fragmented forest), and decreased with scale for 0–30° gentle slope and south- and north-facing aspect. Furthermore, habitat suitability patterns were scale-dependent. These findings highlight the need to determine species–environment associations across multiple scales for habitat management and species conservation. © 2012 The Wildlife Society.     

Environmental heterogeneity as a universal driver of species richness across taxa,biomes and spatial scales

Environmental heterogeneity is regarded as one of the most important factors governing species richness gradients. An increase in available niche space, provision of refuges and opportunities for isolation and divergent adaptation are thought to enhance species coexistence, persistence and diversification. However, the extent and generality of positive heterogeneity–richness relationships are still debated. Apart from widespread evidence supporting positive relationships, negative and hump‐shaped relationships have also been reported. In a meta‐analysis of 1148 data points from 192 studies worldwide, we examine the strength and direction of the relationship between spatial environmental heterogeneity and species richness of terrestrial plants and animals. We find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness. The use of equal‐area study units, spatial grain and spatial extent emerge as key factors influencing the strength of heterogeneity–richness relationships, highlighting the pervasive influence of spatial scale in heterogeneity–richness studies. We provide the first quantitative support for the generality of positive heterogeneity–richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identify specific needs for future comparative heterogeneity–richness research.     

Effects of longitudinal variations in stream habitat structure on fish abundance: an analysis based on subunit-scale habitat classification

SUMMARY 1. Stream reaches contain assortments of various habitat types that can be defined at different spatial scales, such as channel unit (e.g. pools, riffles) and subunit (patches within channel units). We described longitudinal (upstream–downstream) patterns of stream habitat structure by considering subunits as structural elements, and examined their effects on the abundance of masu salmon ( Oncorhynchus masou ) and rosyface dace ( Leuciscus ezoe ) in a third-order tributary of the Teshio River in northern Hokkaido, Japan.
2. Nine subunit types were determined on the basis of water depth, current velocity and substrate, using 0.5 × 0.5 m grids. Although both masu salmon and rosyface dace used pools as a major habitat, the former preferred a subunit type occurring at pool heads (PH subunit) while the latter preferred a slow-current edge type (SE-2 subunit).
3. Along the course of the stream, slow-edge subunits (SE-1, 2 and 3) increased in frequency downstream while fast-edge subunits (FE-1 and 2) decreased, suggesting a downstream development of slow-current edges. Regression analyses indicated that longitudinal variation in masu salmon abundance was explained by the area of PH, rather than pools. Masu salmon density increased with the area of PH. Rosyface dace abundance was explained by a combination of water depth and the area of SE-2, both effects being positive.
4. Longitudinal variations in the abundance of both species were related to the abundance of their preferred habitat at the subunit scale, rather than channel-unit scale. The results emphasise the importance of fine-scale patchiness when examining stream fish habitats.     

Determinants of avian species richness at different spatial scales

ABSTRACT. Studies of factors influencing avian biodiversity yield very different results depending on the spatial scale at which species richness is calculated. Ecological studies at small spatial scales (plot size 0.0025–0.4 km²) emphasize the importance of habitat diversity, whereas biogeographical studies at large spatial scales (quadrat size 400–50,000 km²) emphasize variables related to available energy such as temperature. In order to bridge the gap between those two approaches the bird atlas data set of Lake Constance was used to study factors determining avian species diversity at the intermediate spatial scales of landscapes (quadrat size 4–36 km²). At these spatial scales bird species richness was influenced by habitat diversity and not by variables related to available energy probably because, at the landscape scale, variation in available energy is small. Changing quadrat size between 4 and 36 km², but keeping the geographical extension of the study constant resulted in profound changes in the degree to which the amount of different habitat types was correlated with species richness. This suggests that high species diversity is achieved by different management regimes depending on the spatial scale at which species richness is calculated. However, generally, avian species diversity seems to be determined by spatial heterogeneity at the corresponding spatial scale. Thus, protecting the diversity of landscapes and ecosystems appears to ensure also high levels of species diversity.     

Features of the spatial distribution and size structure of the Pacific lamprey <Emphasis Type="Italic">Lampetra tridentata</Emphasis> in the North Pacific

Results of long-term research on the spatial and vertical distribution of the Pacific lamprey Lampetra tridentata (Richardson, 1836) (the family Petromyzontidae) in the North Pacific, and data on its size structure are submitted. It was shown, that L. tridentate reached its greatest number in the Bering Sea. The maximum concentration of the Pacific lamprey was observed all year round about Navarin Cape, in the Koryak shelf area, at the East Aleutian Islands and at the west coast of the USA, which, apparently, spoke of the increased number of its prey there. On the bottom, the Pacific lamprey was the most numerous at depths of less than 500 m, and in the pelagic, in the upper 100-meter layer. The length of individuals varied in catches from 12 up to 85 cm. The existence of several size groups may indicate that the Pacific lamprey spend several years in the sea. No correlation was revealed between the length of body and fishing depth. The correlations between body length and body weight, body length and condition factor were analyzed. Seasonal dynamics of these parameters were considered.     

Foraging in nature: Contrasting responses to resource heterogeneity at small‐ and large‐spatial scales

A key problem faced by foragers is how to forage when resources are distributed heterogeneously in space. This heterogeneity and associated trade‐offs may change with spatial scale. Furthermore, foragers may also have to optimize acquiring multiple resources. Such complexity of decision‐making while foraging is poorly understood. We studied the butterfly Ypthima huebneri to examine how foraging decisions of adults are influenced by spatial scale and multiple resources. We predicted that, at a small‐spatial scale, the time spent foraging in a patch should be proportional to resources in the patch, but at large‐spatial scales, due to limitations arising from large travel costs, this relationship should turn negative. We also predicted that both adult and larval resources should jointly affect foraging butterflies. To test these predictions, we laid eleven plots and sub‐divided them into patches. We mapped nectar and larval resources and measured butterfly behavior in these patches and plots. We found that adult foraging behavior showed contrasting relationships with adult resource density at small versus large‐spatial scales. At the smaller‐spatial scale, butterflies spent more time feeding in resource‐rich patches, whereas at the large‐scale, butterflies spent more time feeding in resource‐poor plots. Furthermore, both adult and larval resources appeared to affect foraging decisions, suggesting that individuals may optimize search costs for different resources. Overall, our findings suggest that the variation in foraging behavior seen in foragers might result from animals responding to complex ecological conditions, such as resource heterogeneity at multiple spatial scales and the challenges of tracking multiple resources.     

Distinguishing area and habitat heterogeneity effects: a simulation test of the MacNally and Watson (1997) protocol

Distinguishing the roles that different factors, such as sampling effects and habitat heterogeneity, play in generating species‐area curves continues to be difficult in many communities. A recent response to this challenge is the proposal of a ‘zoom’ protocol in which species richness and habitat heterogeneity are sampled in successively larger units (transects or quadrats). The utility of this approach requires that there be justifiable, predictable and unambiguous relationships between richness and heterogeneity. Results of computer simulations that I have done to test the predicted relationships demonstrate, however, that the predicted patterns were not always observed and, on occasion, more complex relationships were observed in their place. While the development of such protocols may increase our understanding of species‐area curves, they are unlikely ever to pronounce unambiguously on their causes.     

Animal species diversity driven by habitat heterogeneity/diversity: the importance of keystone structures

Aim In a selected literature survey we reviewed studies on the habitat heterogeneity–animal species diversity relationship and evaluated whether there are uncertainties and biases in its empirical support. Location World-wide. Methods We reviewed 85 publications for the period 1960–2003. We screened each publication for terms that were used to define habitat heterogeneity, the animal species group and ecosystem studied, the definition of the structural variable, the measurement of vegetation structure and the temporal and spatial scale of the study. Main conclusions The majority of studies found a positive correlation between habitat heterogeneity/diversity and animal species diversity. However, empirical support for this relationship is drastically biased towards studies of vertebrates and habitats under anthropogenic influence. In this paper, we show that ecological effects of habitat heterogeneity may vary considerably between species groups depending on whether structural attributes are perceived as heterogeneity or fragmentation. Possible effects may also vary relative to the structural variable measured. Based upon this, we introduce a classification framework that may be used for across-studies comparisons. Moreover, the effect of habitat heterogeneity for one species group may differ in relation to the spatial scale. In several studies, however, different species groups are closely linked to ‘keystone structures’ that determine animal species diversity by their presence. Detecting crucial keystone structures of the vegetation has profound implications for nature conservation and biodiversity management.     

不同尺度上环境因子对常绿阔叶林群落的谱系结构的影响

群落的谱系结构是反映作用于群落组成的各种生态过程的综合指标。通过研究群落的谱系结构, 能够有效地推断形成群落谱系结构的生态过程。该文从环境因子(海拔、地形、pH、土壤湿度和土壤元素等)对群落谱系结构的影响这一视角出发, 采用圆形随机取样, 在半径为5、25、50、75和100 m 5个尺度上, 深入研究了古田山24 hm²永久样地群落的谱系结构。研究发现: 古田山样地在所有研究尺度上(半径 > 5 m)都表现为谱系聚集, 随着尺度的增加, 群落的聚集程度呈现出先增加后下降的格局。采用多元线性回归模型分析环境因子对群落谱系结构的影响时发现: 随着尺度的增加, 环境因子对群落谱系结构的影响逐渐增强; 在小尺度上, 环境因子对谱系结构没有显著影响, 这可能是由于小尺度上近缘种之间较强的竞争排斥作用所致。当尺度达到100 m半径时, 高海拔区域表现出谱系发散格局, 而低海拔区域保持谱系聚集, 这可能是由于古田山样地海拔较高的地带生境异质性较强和较大的干扰所致。该研究在所有的尺度上都表现出显著的谱系聚集, 与中性理论所预测的群落是物种的随机组合、无谱系结构相反, 因而为生态位理论提供了证据。     

Drivers for genetic structure at different geographic scales for Pacific red snapper (Lutjanus peru) and yellow snapper (Lutjanus argentiventris) in the tropical eastern Pacific

The tropical eastern Pacific (TEP) is a highly dynamic region and a model system to study how habitat discontinuities affect the distribution of shorefishes, particularly for species that display ontogenetic habitat shifts, including snappers (Lutjanidae). To evaluate the genetic structure of the Pacific red snapper (Lutjanus peru) and the yellow snapper (Lutjanus argentiventris) throughout their distribution range along the TEP, 13 and 11 microsatellite loci were analysed, respectively. The genetic diversity of L. peru (N = 446) and L. argentiventris (N = 170) was evaluated in 10 and 5 localities, respectively, showing slightly higher but non-significant values in the Gulf of California for both species. The genetic structure analysis identified the presence of significant genetic structure in both species, but the locations of the identified barriers for the gene flow differed between species. The principal driver for the genetic structure at large scales >2500 km was isolation by distance. At smaller scales (<250 km), the habitat discontinuity for juveniles and adults and the environmental differences throughout the distribution range represented potential barriers to gene flow between populations for both species.     

Scale effects of habitat selection in breeding Nuthatches (Sitta europaea) in two different woodlands

Summary Observations over a 14 year study revealed that Nuthatches had significantly higher breeding densities in a deciduous woodland than in coniferous-mixed woodland. However, the variability in breeding densities between years correlated in the two woodlands. In selecting a breeding site, birds may have to decide on different spatial scales. Possibly, these scales are reflected in a hierarchical series of decisions that might differ according to habitat quality. We correlated the frequency of nest box occupation by Nuthatches over 14 years with habitat parameters and PCA scores of different spatial scales (roughly 0.1 ha and 1 ha). In the coniferous-mixed woodland Nuthatches preferred similar habitat parameters at the small and the large scale like oaks, open areas and forest edge. In the deciduous woodland, however, a marked difference in habitat preference between small and large scale was shown: on the small scale parameters directly associated with nest box characteristics were significantly preferred. On the large scale only structural and floristic parameters associated with the general quality of the woodland were important for breeding site selection. Here tree stands with a superabundance of pine trees were avoided and the abundant oak trees were not important for the selection of a nest box. By further subdividing the very heterogeneous deciduous woodland into two parts, a stand of young trees and the rest of the woodland, opposing habitat choices could be shown. Thus scale effects of habitat choice are dependent upon habitat quality and heterogeneity.

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Einfluß des räumlichen Maßstabs auf die Habitatwahl von Kleibern (Sitta europaea) zur Brutzeit in zwei unterschiedlichen Waldgebieten

Zusammenfassung In einer Langzeituntersuchung über 14 Jahre wurde die Nistkastenbelegung durch Kleiber in zwei unterschiedlichen Waldgebieten, einem Laubwald und einem Nadel-Laub-Mischwald, untersucht. Im Laubwald waren 80 Nistkästen, im Nadel-Laub-Mischwald 92 Nistkästen in 30 × 30 m Rastern aufgehängt. In jedem dieser Rasterquadrate wurden 18 Habitatparameter aufgenommen. Beide Waldgebiete unterschieden sich in den meisten Parametern signifikant. Die Brutpaardichten waren im Laubwald signifikant höher als im Nadel-Laub-Mischwald. Jedoch korrelierte die Variabilität der Brutpaardichten zwischen den Untersuchungszeiträumen in beiden Gebieten. Nistplatzwahl wurde in zwei räumlichen Maßstäben untersucht. Der kleine Maßstab umfaßte die Fläche von 30 × 30 m um jeden Nistkasten (ca. 0,1 ha), der große Maßstab hatte die Fläche von ca. 1 ha (9 Nistkästen, 90 × 90 m). Auf dem kleinen Maßstab wurde die Nistkastenbelegung für jeden Nistkasten über den Untersuchungszeitraum aufsummiert. Auf dem großen Maßstab wurde für jeden Nistkasten und die ihn umgebenden 8 Nistkästen die Belegung gemittelt. Dadurch ergaben sich für großen und kleinen Maßstab identische Stichprobengrößen. Die so ermittelten Nistkastenbelegungen wurden mit den Habitatparametern und entsprechenden Hauptkomponentenfaktoren korreliert.Im Nadel-Laub-Mischwald bevorzugten Kleiber bei beiden Maßstäben Eichen, offene Flächen und Waldränder. Im Laubwald unterschied sich die Habitatpräferenz zwischen den Maßstäben: bei kleinem Maßstab wurden Nistkasten-Parameter (wie z. B. die Höhe) signifikant bevorzugt. Bei großem Maßstab hingegen waren nur Strukturparameter sowie Pflanzenarten für die Nistplatzwahl entscheidend. Waldbereiche mit einem Überangebot an Kiefern wurden gemieden, die häufig und gleichmäßig vorkommenden Eichen hatten bei der Nistplatzwahl keine Bedeutung. Bei weiterer Unterteilung des sehr heterogenen Laubwaldes in zwei Einheiten, einen jungen Baumbestand und den Rest des Waldes, wurde gegensätzliche Habitatwahl nachgewiesen. Daraus folgt, daß bei der Habitatwahl durch unterschiedliche Maßstäbe verursachte Effekte von Habitatqualität und -heterogenität abhängen.

     

Morphometric discrimination of early life stage Lampetra tridentata and L. richardsoni (Petromyzonidae) from the Columbia River Basin

The effectiveness of morphometric and meristic characteristics for taxonomic discrimination of Lampetra tridentata and L. richardsoni (Petromyzonidae) during embryological, prolarval, and early larval stages (i.e., age class 1) were examined. Mean chorion diameter increased with time from fertilization to hatch and was significantly greater for L. tridentata than for L. richardsoni at 1, 8, and 15 days postfertilization. Lampetra tridentata larvae had significantly more trunk myomeres than L. richardsoni; however, trunk myomere numbers were highly variable within species and deviated from previously published data. Multivariate examinations of prolarval and larval L. tridentata (7.2-11.0 mm; standard length) and L. richardsoni (6.6-10.8 mm) were conducted based on standard length and truss element lengths established from eight homologous landmarks. Principal components analysis indicated allometric relationships among the morphometric characteristics examined. Changes in body shape were indicated by groupings of morphometric characteristics associated with body regions (e.g., oral hood, branchial region, trunk region, and tail region). Discriminant function analysis using morphometric characteristics was successful in classifying a large proportion (> 94.7%) of the lampreys sampled.     

Determinants of preferred intertidal feeding habitat for Eastern Curlew: A study at two spatial scales

Abstract Broadscale habitat use by Eastern Curlews (Numenius madagascariensis) in their non‐breeding range in eastern Australia was assessed using low tide surveys on feeding grounds, where 60 skilled volunteers made repeated counts of the birds on intertidal flats, across 41% (9500 ha) of the intertidal habitat within Moreton Bay, Australia. We analysed 32 defined sections of intertidal flat, of roughly equal area (mostly 200–400 ha), which varied greatly in their curlew density (2–47 birds per 100 ha) and also in substrate and other environmental features. Sites with the least resistant substrates had densities three times those with the most resistant substrates. Of 10 environmental characteristics measured for each site, substrate resistance was the best predictor of curlew density (r² = 0.45). Characteristics that were poor predictors included distance to the nearest roost, level of human disturbance and distance to urban settlement. For a finer‐scale assessment, microhabitat use and feeding behaviour were recorded during low tide within 12 intertidal flats, which varied in size (23–97 ha), substrate, topography and other features. Across all flats, curlews strongly preferred to feed relatively close (0–50 m) to the low‐water line. They fed on a variety of substrates (including sand, sandy‐mud, mud and seagrass) in broadly similar proportions to their occurrence in the habitat. There was a statistically significant preference for sand, although its magnitude was not strong. These results indicate that curlews select habitat most strongly at a between‐flat rather than within‐flat scale.     

Floristic heterogeneity at Ngogo,Kibale National Park,Uganda and possible implications for habitat use by chimpanzees (Pan troglodytes)

Tropical forest tree communities exhibit heterogeneity at multiple spatial scales, with important implications for animals relying on these resources. However, different organisms may perceive heterogeneity in the floristic community in very different ways. Here, we characterize the overall extent of heterogeneity in the floristic community at Ngogo, in Kibale National Park, Uganda. Also, using information from studies on the diet of chimpanzees (Pan troglodytes) inhabiting Ngogo, we quantify the extent to which the habitat is likely perceived as heterogeneous by this species. The forest as a whole is slightly more diverse than comparable sites in the Congo Basin, but this diversity is driven by a relatively high proportion of rare species represented by few individuals. From the perspective of chimpanzees, the forest is, unsurprisingly, even more heterogeneous. Species that provide fruit for chimpanzees during times of low overall fruit abundance and that display interindividual synchrony in fruiting were the most common chimpanzee resource in our sample, whereas species that provide fruit during times of low overall fruit abundance and that display asynchronous fruiting were the least common. We discuss the implications of the differences in density and distribution of various classes of resources for chimpanzee habitat use and foraging efficiency.     

老龄阔叶红松林下层木空间分布的生境关联分析

基于老龄阔叶红松林30 hm2(500 m×600 m)固定监测样地,分析了老龄阔叶红松林下层(1 cm≤DBH≤5 cm)14个主要树种(个体数>300)的空间分布与空间距离、地形因子及郁闭度之间关联性。结果显示:(1)14个种都显示出了聚集分布,绝大多数种呈现出了在小距离级上呈显著正空间自相关大距离级上呈现显著负空间自相关的趋势。(2)6个种显示与空间距离显著相关即存在本身的聚集效应,占被检验种的42.86%;7个种显示出与环境(地形、郁闭度)有显著相关性即存在显著的生境偏好,占50%。个体数大于1000的7优势种中有5个种空间分布与生境显著相关,5个种与空间距离显著相关。(3)色木槭、千金榆显示出了对低海拔、向阳坡生境类型的偏好,簇毛槭、花楷槭、毛榛显示出对高海拔、坡度陡、向阴坡生境类型的偏好。这表明,老龄阔叶红松林下层木多数树种为聚集分布,其聚集性的空间分布受生境及自身聚集效应的重要影响。多个树种对同种生境的偏好体现了植物利用资源的相似性和生态位的重叠,对不同生境的偏好体现了物种间的排斥性,这是长期适应不同微环境,利用不同空间资源的结果,也是生态位分离的反映。     

Probing whole‐stream metabolism: influence of spatial heterogeneity on rate estimates

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