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1.
Wali  Mohan K. 《Plant and Soil》1999,213(1-2):195-220
Plant and Soil - Soil and vegetation development on surface-mined coal sites in a mixed grass prairie region were studied as (a) naturally revegetated chronosequences of 1, 7, 17, 30 and 45-year...  相似文献   

2.
Self-similar distributions of species across a landscape have been proposed as one potential cause of the well-known species-area relationship. The best known of these proposals is in the form of a probability rule for species occurrence. The application of this rule to the number of species occurring in primary well-shaped rectangles within the landscape gives rise to a discrete power law for species-area relationships. However, this result requires a specific scheme for bisecting the landscape to generate the rectangles. Some additional, more general consequences of the probability rule are presented here. These include the result that the number of species in a well-shaped rectangle depends on its location, not just on its area. In addition, a self-similar landscape contains well-shaped rectangles that are, in fact, not self-similar. The probability rule in general produces testable predictions about how and where species are distributed that are independent of the power law.  相似文献   

3.
Peat accumulating mires are important sources of the greenhouse gas methane. Methane emissions and methanogenic Archaea communities have been shown to differ between fens and bogs, implying that mire succession includes an ecological succession in methanogen communities. We investigated methane production and the methanogen communities along a chronosequence of mires (ca. 100-2,500 years), which consisted of five sites (1-5) located on the land-uplift coast of the Gulf of Bothnia. Methane production was measured in a laboratory incubation experiment. Methanogen communities were determined by amplification of a methyl coenzyme M-reductase (mcr) gene marker and analyzed by terminal-restriction fragment length polymorphism. The terminal-restriction fragment length polymorphism fingerprinting resulted in 15 terminal restriction fragments. The ordination configuration of the terminal restriction fragments data, using nonmetric multidimensional scaling, showed a clear gradient in the methanogen community structure along the mire chronosequence. In addition, fingerprint patterns of samples from the water table level and 40 cm below differed from one another in the bog site (site 5). Methane production was negligible in the three youngest fen sites (sites 1-3) and showed the highest rates in the oligotrophic fen site (site 4). Successful PCR amplification using mcr gene primers revealed the presence of a methanogen community in all five sites along the study transect.  相似文献   

4.
Experimental studies reveal generally slow but variable colonization rates in deep-sea soft bottoms. Species successions following biological disturbance appear to be complex and unpredictable, potentially playing a role in structuring these diverse communities. In contrast, physical processes probably play a prominent role in the rapid species turnovers observed at hydrothermal vents. Better information concerning disturbance regimes, recruitment processes and resource utilization is required to elaborate successional mechanisms in both soft-bottom and vent environments.  相似文献   

5.
We examined the species-area relationship for three historically distinct subsets of Lesser Antillean birds identified by molecular phylogenetic analysis of island and continental populations. The groups comprised recent colonists from continental or Greater Antillean source populations, old taxa having recently expanded distributions within the Lesser Antilles, and old endemic taxa lacking evidence of recent dispersal between islands. The number of young taxa was primarily related to distance from the source of colonists in South America. In a multiple regression, the logarithmic slope of the species-area relationship for this group was shallow (0.066+/-0.016). Old endemic taxa were restricted to islands with high elevation, and within this subset, species richness was related primarily to island area, with a steep slope (0.719+/-0.110). The number of recently spread endemic taxa was related primarily to island elevation, apparently reflecting the persistence of such populations on islands with large areas of forested and montane habitats. Historical analysis of the Lesser Antillean avifauna supports the dynamic concept of island biogeography of MacArthur and Wilson, rather than the more static view of David Lack, in that colonists exhibit dispersal limitation and extinction plays a role in shaping patterns of diversity. However, the avifauna of the Lesser Antilles is probably not in equilibrium at present, and the overall species-area relationship might reflect changing proportions of historically distinguishable subsets of species.  相似文献   

6.
Although many forensic entomological studies have described patterns of carrion insect succession and theoretical studies have explained interspecific interactions that drive succession, empirical studies on the quantitative and ecological aspects of carrion insect succession, such as the degree of historical contingency in community assembly and interspecific interactions during succession, are limited. In this study, I investigated variability in the successional pathways of carrion insect communities in rat carcasses and their decomposition processes, and examined the interspecific interactions involved in succession, such as the effects of carcass utilization by early‐arriving species on late‐arriving species. Members of the families Calliphoridae and Formicidae and the species Eusilpha japonica (Motschulsky) and Nicrophorus concolor Kraatz were chiefly observed. In almost all carcasses, formicid species arrived first, and calliphorid species and E. japonica arrived simultaneously or immediately after. Nicrophorus concolor arrived last, with its time of colonization occurring earlier in carcasses with greater E. japonica abundance. Meanwhile, the early‐arriving species decreased when N. concolor arrived. Nicrophorus concolor tended to reproduce on carcasses with lower cumulative abundance of early‐arriving species and tended to feed on carcasses with greater cumulative abundance of early‐arriving species. These results show that the successional pathways of the chief carrion insect species are highly consistent among carcasses. In contrast, early‐arriving species seem to influence the utilization patterns of carcasses by late‐arriving species, and therefore produce variability in the decomposition process. These results also show that succession could be driven by facilitation and interspecific competition between early‐arriving and late‐arriving species.  相似文献   

7.
Estimates of paleodiversity patterns through time have relied on datasets that lump taxonomic occurrences from geographic areas of varying size per interval of time. In essence, such estimates assume that the species–area effect, whereby more species are recorded from larger geographic areas, is negligible for fossil data. We tested this assumption by using the newly developed Miocene Mammal Mapping Project database of western North American fossil mammals and its associated analysis tools to empirically determine the geographic area that contributed to species diversity counts in successive temporal bins. The results indicate that a species–area effect markedly influences counts of fossil species, just as variable spatial sampling influences diversity counts on the modern landscape. Removing this bias suggests some traditionally recognized peaks in paleodiversity are just artifacts of the species–area effect while others stand out as meriting further attention. This discovery means that there is great potential for refining existing time-series estimates of paleodiversity, and for using species–area relationships to more reliably understand the magnitude and timing of such biotically important events as extinction, lineage diversification, and long-term trends in ecological structure.  相似文献   

8.
We studied microbial community composition in a primary successional chronosequence on the forefront of Lyman Glacier, Washington, United States. We sampled microbial communities in soil from nonvegetated areas and under the canopies of mycorrhizal and nonmycorrhizal plants from 20- to 80-year-old zones along the successional gradient. Three independent measures of microbial biomass were used: substrate-induced respiration (SIR), phospholipid fatty acid (PLFA) analysis, and direct microscopic counts. All methods indicated that biomass increased over successional time in the nonvegetated soil. PLFA analysis indicated that the microbial biomass was greater under the plant canopies than in the nonvegetated soils; the microbial community composition was clearly different between these two types of soils. Over the successional gradient, the microbial community shifted from bacterial-dominated to fungal-dominated. Microbial respiration increased while specific activity (respiration per unit biomass) decreased in nonvegetated soils over the successional gradient. We proposed and evaluated new parameters for estimating the C use efficiency of the soil microbial community: “Max” indicates the maximal respiration rate and “Acc” the total C released from the sample after a standard amount of substrate is added. These, as well as the corresponding specific activities (calculated as Max and Acc per unit biomass), decreased sharply over the successional gradient. Our study suggests that during the early stages of succession the microbial community cannot incorporate all the added substrate into its biomass, but rapidly increases its respiration. The later-stage microbial community cannot reach as high a rate of respiration per unit biomass but remains in an “energy-saving state,” accumulating C to its biomass. Received: 4 June 1998 / Accepted: 11 January 1999  相似文献   

9.
Human impacts on the species-area relationship in reef fish assemblages   总被引:2,自引:0,他引:2  
The relationship between species richness and area is one of the oldest, most recognized patterns in ecology. Here we provide empirical evidence for strong impacts of fisheries exploitation on the slope of the species–area relationship (SAR). Using comparative field surveys of fish on protected and exploited reefs in three oceans and the Mediterranean Sea, we show that exploitation consistently depresses the slope of the SAR for both power-law and exponential models. The magnitude of change appears to be proportional to fishing intensity. Results are independent of taxonomic resolution and robust across coral and rocky reefs, sampling protocols and statistical methods. Changes in species richness, relative abundance and patch occupancy all appear to contribute to this pattern. We conclude that exploitation pressure impacts the fundamental scaling of biodiversity as well as the species richness and spatial distribution patterns of reef fish. We propose that species–area curves can be sensitive indicators of community-level changes in biodiversity, and may be useful in quantifying the human imprint on reef biodiversity, and potentially elsewhere.  相似文献   

10.
Community assembly during succession can be constrained by both local and regional factors. Despite an increasing regional species pool size during succession, we found a limit on the number of species in 1 × 1 m plots in dune slacks. Three alternative hypotheses (habitat heterogeneity, dispersal limitation and niche limitation) explaining this community saturation were tested. A null model analysis showed that species richness in the plots had an unusually low variance suggesting that beta habitat diversity was not likely to explain the limitation on species richness. Because we did not find a correlation between the distribution of species over the slack and their dispersal capacity, we also excluded the dispersal limitation hypothesis. Finally, a guild proportionality analysis revealed that the abundances of forb, graminoid and ruderal species showed low an unusually low variance over all age classes involved. This provides evidence for nonrandom community assembly during succession, likely to be determined by competitive exclusion among species of the same guild.  相似文献   

11.
12.
Aims Studying plant ecological succession provides insights into the spatiotemporal processes underlying community assembly and is of primary importance for restoration ecology. We investigate here colonization events and local community assembly over an original primary succession occurring on roadcuts after roadwork. For this, we addressed both the changes in species presence-absence (incidence data) to highlight pre-establishment filters and in species relative abundances to further assess the influence of local biotic processes.Methods We studied 43 limestone roadcuts in Mediterranean France, covering five age classes up to an age of 80 years, along with 13 natural cliffs as a reference, and we counted 14322 plant individuals on these sites. We applied a constrained nonsymmetric correspondence analysis of both the incidence (presence-absence) and abundance data to assess the variation of these data along the chronosequence.Important findings Along the first 30 years, the initially abundant short-lived species declined both in terms of incidence and abundance and were replaced by longer lived herbaceous and woody species. This first phase was characterized by species that are widespread in the surrounding scrublands and was comparable to an early secondary succession there. After 30 years, there were continuing changes in incidence data with age, but no more significant change in species' abundances. This second phase was marked by the late colonization of specialists that did not become dominant. Although colonization and establishment limitation was thereby apparent for specialist species, a slow convergence of community composition toward the situation of natural cliffs could be detected in the older stages of the chronosequence. These findings convey insights into the natural dynamics of man-made outcrop plant communities and may be useful for the ecological management and restoration of such contexts. It also illustrates the interest of comparing incidence and abundance data to investigate the relative influence of ecological determinants on the assembly of plant communities.  相似文献   

13.
Eutrophication, coupled with loss of herbivory due to habitat degradation and overharvesting, has increased the frequency and severity of macroalgal blooms worldwide. Macroalgal blooms interfere with human activities in coastal areas, and sometimes necessitate costly algal removal programmes. They also have many detrimental effects on marine and estuarine ecosystems, including induction of hypoxia, release of toxic hydrogen sulphide into the sediments and atmosphere, and the loss of ecologically and economically important species. However, macroalgal blooms can also increase habitat complexity, provide organisms with food and shelter, and reduce other problems associated with eutrophication. These contrasting effects make their overall ecological impacts unclear. We conducted a systematic review and meta‐analysis to estimate the overall effects of macroalgal blooms on several key measures of ecosystem structure and functioning in marine ecosystems. We also evaluated some of the ecological and methodological factors that might explain the highly variable effects observed in different studies. Averaged across all studies, macroalgal blooms had negative effects on the abundance and species richness of marine organisms, but blooms by different algal taxa had different consequences, ranging from strong negative to strong positive effects. Blooms' effects on species richness also depended on the habitat where they occurred, with the strongest negative effects seen in sandy or muddy subtidal habitats and in the rocky intertidal. Invertebrate communities also appeared to be particularly sensitive to blooms, suffering reductions in their abundance, species richness, and diversity. The total net primary productivity, gross primary productivity, and respiration of benthic ecosystems were higher during macroalgal blooms, but blooms had negative effects on the productivity and respiration of other organisms. These results suggest that, in addition to their direct social and economic costs, macroalgal blooms have ecological effects that may alter their capacity to deliver important ecosystem services.  相似文献   

14.
An experiment was carried out in two heathland ecosystems, one dominated by Calluna vulgaris and the other by Molinia caerulea, to analyse the effects of soil organic matter accumulation and nutrient mineralization on plant species dynamics during succession. The experiment included one treatment that received nutrient solution and two treatments where the rate of soil organic matter accumulation was reduced by removing litter or accelerated by adding litter. In a fourth treatment the C. vulgaris litter produced in the C. vulgaris-dominated plots was replaced by litter of M. caerulea and vice versa. Treatments were applied over 8 years. Addition of nutrient solution caused C. vulgaris to decline, and grass species to increase sharply, compared to the control plots. Addition of litter enhanced both N mineralization and the biomass of M. caerulea and Deschampsia flexuosa but reduced the biomass of C. vulgaris. The effects of replacing C. vulgaris litter by M. caerulea litter, or vice versa, on N mineralization and species dynamics could not be attributed to differences between the decomposability of the different litter materials that were transferred. The results confirm the hypothesis that increased litter inputs accelerate the rate of species replacement during succession.  相似文献   

15.
We analysed the relationship between plant species richness and productivity on first-year-old fields at two similar sites in central Europe. At both sites, a wide range of productivity levels was available resulting from different long-term fertilisation. In order to identify underlying mechanisms of the species richness–productivity relationship we included the seasonal dynamics and the number of individuals of each species in our analysis. We sampled 10 and 21 plots, respectively, at the two sites in May, June and July by harvesting all aboveground parts of vascular plants in 0.25 m2 subplots. Species richness, number of individuals of each species and community biomass as a surrogate of productivity were recorded in each sample.At one site, the relationship between species richness and biomass was significantly positive in the May and June harvest. This relationship disappeared in the July harvest due to a reduction in species richness at high productivity levels. The relations between species richness and number of individuals and between number of individuals and biomass paralleled the species richness–productivity relation but the individual number–biomass relationship remained positive until the last harvest. Between-species differences in individual number–community biomass relationships and their seasonal dynamics revealed “interspecific competitive exclusion” even though the species richness–biomass relationships were not negative or hump-shaped. At the second site, species richness was not related to productivity or to number of individuals. Our study demonstrated the importance of temporal dynamics and regional processes in understanding species richness–productivity patterns.  相似文献   

16.
《Ecology and evolution》2021,11(24):17744
Biotic and abiotic factors interact with dominant plants—the locally most frequent or with the largest coverage—and nondominant plants differently, partially because dominant plants modify the environment where nondominant plants grow. For instance, if dominant plants compete strongly, they will deplete most resources, forcing nondominant plants into a narrower niche space. Conversely, if dominant plants are constrained by the environment, they might not exhaust available resources but instead may ameliorate environmental stressors that usually limit nondominants. Hence, the nature of interactions among nondominant species could be modified by dominant species. Furthermore, these differences could translate into a disparity in the phylogenetic relatedness among dominants compared to the relatedness among nondominants. By estimating phylogenetic dispersion in 78 grasslands across five continents, we found that dominant species were clustered (e.g., co‐dominant grasses), suggesting dominant species are likely organized by environmental filtering, and that nondominant species were either randomly assembled or overdispersed. Traits showed similar trends for those sites (<50%) with sufficient trait data. Furthermore, several lineages scattered in the phylogeny had more nondominant species than expected at random, suggesting that traits common in nondominants are phylogenetically conserved and have evolved multiple times. We also explored environmental drivers of the dominant/nondominant disparity. We found different assembly patterns for dominants and nondominants, consistent with asymmetries in assembly mechanisms. Among the different postulated mechanisms, our results suggest two complementary hypotheses seldom explored: (1) Nondominant species include lineages adapted to thrive in the environment generated by dominant species. (2) Even when dominant species reduce resources to nondominant ones, dominant species could have a stronger positive effect on some nondominants by ameliorating environmental stressors affecting them, than by depleting resources and increasing the environmental stress to those nondominants. These results show that the dominant/nondominant asymmetry has ecological and evolutionary consequences fundamental to understand plant communities.  相似文献   

17.
The mycorrhizal association between fungi and plants is thought to be an important component of the functional diversity of plant communities, although evidence is weak. We explored community-level changes to mycorrhizal features and leaf traits along a primary successional gradient on a sedimentation coast. We found that community weighted mean values of mycorrhizal features and leaf traits varied systematically along the successional series, representing a transition from communities dominated by more stress-tolerant plant species (less mycorrhizal colonization and lower specific leaf area) to less stress-tolerant plant species (higher mycorrhizal colonization and specific leaf area). Despite the co-variation in leaf traits and mycorrhizal features at the community level, only mycorrhizal features showed an increasing functional diversity with successional age. These results suggest that mycorrhizal fungi should not be forgotten in trait-based plant community ecology.  相似文献   

18.
Interpretations of successional patterns in ecological communities have traditionally adhered to the dichotomy between the Clementsian view that emphasizes community level processes and the Gleasonian view that stresses individual population responses. The present study evaluates the relative importance of each type of process during protistan primary succession in initially barren aquatic isolates (200-1 plastic pools) over a 170-d period. Species availability to these systems was manipulated by erecting exclosures around individual mesocosms to successively eliminate access to different dispersal vectors responsible for passive protistan dispersal. Increased exclosure significantly reduced access of autotrophs to the pools, but had little effect on heterotroph species availability. The species replacement process was directional through time and occurred at similar rates in all treatments. Both lower and upper temporal boundaries of heterotrophic and autotrophic species were contagious through time, as predicted by the Clementsian hypothesis, although the independence of these two boundary types suggested an individualistic model. Dominant and subdominant species were correlated into four temporal groups: pioneer, early successional, mid-successional, late successional. The dominance of several mid- and late successional species was reduced with increased exclosure. The loss of these species from successional pathways in more exclosed pools had no significant effect on the distribution of other species within the same temporal group. However, the establishment of these other mid- and late successional species may be dependent on initial colonization by pioneer and early successional species. Increased abundances of mid- and late successional species in less exclosed pools coincided with significant attenuations in the distribution of many early successional species. Interactions between successional groups may be related to the supply of inorganic resources as well as allelopathic effects. Patterns of protist succession are the result of both population and community processes; while species-specific characteristics (i.e., dispersal ability) may dominate the process in more isolated systems, increased species availability increases the relative importance of interspecific interactions.  相似文献   

19.
The effects of patch size on the colonisation and succession of intertidal invertebrates and algae were investigated in an estuary near Sydney, New South Wales, Australia. The specific aim was to test explicitly for the presence of a species-area relationship, and examine whether this could be explained by the random placement hypothesis (i.e. that the number of species per unit area was the same on patches of different sizes). In addition, I tested the extent to which differences in numbers of species reflected differences in the composition of assemblages. Wooden panels of three different sizes (10 × 10 cm, 20 × 20 cm and 40 × 40 cm) were placed in the field on intertidal oyster leases in each of two different experimental trials: spring (October 1994) and summer (January 1995). Independent replicate measures of the number of colonising species on panels were obtained after different periods of time, up to 25 months. I also obtained measures of abundance of individual species and composition of assemblages on panels of different sizes. This allowed specific tests of the hypothesis that the size of the patch being colonised is important in structuring these assemblages. The strength of the species-area relationship increased through time on panels submersed in October, but the trend was reversed for panels submersed in January. There was a significant interaction between factors of patch size and time of submersion for multivariate measures of differences in composition among replicates. The random placement hypothesis was supported in certain situations, but not in others. When rejected, it was for different reasons on panels submersed in the two different trials. Panels initiated in October tended to have proportionally greater numbers of species per unit area on larger panels, while the panels initiated in January tended to have more species per unit area on smaller panels. There was an identifiable relationship between differences in numbers of species and differences in species composition for panels submersed in October. This was not true, however, for panels submersed in January, where the species-area relationship did not hold after longer periods. The succession of organisms through time was, overall, more important in structuring the assemblages than was the size of the patch being colonised. The species-area relationship should not necessarily be regarded as a truism – it did not always hold in this system. The initial timing of experiments with respect to recruitment and succession influenced the results. Received: 16 March 1998 / Accepted: 5 October 1998  相似文献   

20.
Using a natural microecosystem, I test the contribution of the metapopulation effect to the species-area relationship, relative to that of the combined effects of habitat heterogeneity and sampling. The relative contributions were approximately equal, but with further relaxation of the fragmented community, the metapopulation effect is expected to increase. Predators had a greater slope to their species-area relationship than non-predators, and the habitat-plus-sampling effect was greater in predators than non-predators. This is the first attempt, to my knowledge, to quantify the causes of the species-area relationship.  相似文献   

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