Effects of natural habitat fragmentation on the species richness, diversity, and composition of cliff vegetation

2000 ◽  
Vol 78 (6) ◽  
pp. 786-797 ◽  
Author(s):  
A.R. Haig ◽  
U. Matthes ◽  
D.W. Larson
Keyword(s):  
Species Richness ◽  
Habitat Fragmentation ◽  
Natural Habitat ◽  
Cliff Vegetation

Effects of natural habitat fragmentation on the species richness, diversity, and composition of cliff vegetation

2000 ◽  
Vol 78 (6) ◽  
pp. 786-797 ◽  
Author(s):  
A R Haig ◽  
U Matthes ◽  
D W Larson
Keyword(s):  
Species Richness ◽  
Habitat Fragmentation ◽  
Plant Species ◽  
Significant Relationship ◽  
Vascular Plants ◽  
Multivariate Analyses ◽  
Natural Habitat ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Cliff Vegetation

Plant species richness, diversity, and some aspects of species composition were measured on natural limestone cliff fragments of varying size within the Niagara Escarpment Biosphere Reserve, Canada. This information was collected because knowledge about how different components of community structure change in response to natural fragmentation may permit the prediction of the effects of future anthropogenic fragmentation. The number and relative abundance of vascular plant, bryophyte, and lichen species were determined on cliff fragments that varied in area from 185 to 126 000 m2. Latitude, aspect, percent available photosynthetically active radiation on the cliff face, distance from the nearest neighbouring cliff, and length of the nearest neighbouring cliff were also measured. Regression analysis was used to test for a significant relationship between fragment area and diversity of vascular plants, bryophytes, and lichens both separately and combined. Multiple regression with all subsets selection was used to find the best predictors of species richness from among all variables measured for the 21 cliff fragments. Multivariate analyses were used to study the effect of fragmentation on the structure of the vegetation as a whole. The results showed no significant relationship between cliff fragment area and richness or diversity for vascular plants and bryophytes, and only a marginally significant increase in richness with area for lichens. The multivariate analyses also showed that only one community type exists, and that its structure mainly varies as a function of latitude. These results indicate that very small fragments of cliff face can support a similar plant biodiversity as do large continuous portions of the Niagara Escarpment.Key words: habitat fragmentation, plant species richness, lichens, bryophytes, cliff vegetation.

scholarly journals Family graveyards form underappreciated local plant diversity hotspots in China's agricultural landscapes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cheng Gong ◽  
Liangtao Li ◽  
Jan C. Axmarcher ◽  
Zhenrong Yu ◽  
Yunhui Liu
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Natural Habitat ◽  
Plant Species Richness ◽  
Agricultural Landscapes ◽  
Natural Habitats ◽  
Landscape Features ◽  
Habitat Islands ◽  
Local Plant ◽  
Ecological Functioning

AbstractIn the intensively farmed, homogenous agricultural landscape of the North China Plain, family graveyards form distinct cultural landscape features. In addition to their cultural value, these graveyards represent semi-natural habitat islands whose potential roles in biodiversity conservation and ecological functioning has remained poorly understood. In this study, we investigated plant species richness on 199 family graveyards of different ages and sizes. In accordance with biogeography theory, both overall and insect-pollinated plant species richness increased with area and age of graveyards. Even small graveyards show a strong potential for conserving local plant richness, and a mosaic of both large and small family graveyards could play an important role in the conservation of farmland biodiversity and related ecosystem functions. The launch of agri-environmental measures that conserve and create semi-natural habitats, in turn benefitting agricultural biodiversity and ecological functioning, has proven difficult in China due to the shortage of dispensable arable land. Given the great value of family graveyards as semi-natural habitats reflected in our study, we propose to focus preliminary efforts on conserving these landscape features as existing, widespread and culturally important semi-natural habitat islands. This would represent an effective, complementary policy to a subsequent re-establishment of other semi-natural habitats for the conservation of biodiversity and ecological functioning in agricultural landscapes.

scholarly journals Environmental filtering and spillover explain multi-species edge responses across agricultural boundaries in a biosphere reserve

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. van Schalkwyk ◽  
J. S. Pryke ◽  
M. J. Samways ◽  
R. Gaigher
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Habitat Quality ◽  
Environmental Variables ◽  
Natural Habitat ◽  
Environmental Filtering ◽  
Biosphere Reserve ◽  
Natural Habitats ◽  
Habitat Specificity ◽  
Induced Changes

Abstract To ensure integrity of protected areas we need to understand how species respond to anthropogenic borders. We investigate, from a metacommunity perspective, the direct and indirect mechanisms by which transformed areas affect distribution patterns of ground-living arthropod assemblages inhabiting an extensive protected area adjacent to fruit orchards in an important biosphere reserve. Arthropods and environmental variables were sampled along transects perpendicular to natural-orchard edges. Influence of distance from orchard boundary, degree of impermeability of the boundary, orchard habitat quality (local scale land-use intensity), and edge-induced changes in local environmental variables on arthropod species richness and composition in non-crop habitats were assessed. Arthropod groups were assessed in terms of habitat fidelity: species associated with natural habitat (stenotopic species), those within crop habitat (cultural species), and those showing no preference for either habitat (ubiquitous species). Spillover resulted in higher cultural species richness near edges, but not higher overall species richness. Environmental filtering was important for stenotopic species composition, which was influenced by edge-induced changes in environmental variables. Ubiquitous species composition was determined by orchard impermeability. Increased orchard habitat quality was associated with higher cultural and ubiquitous species richness. The effects of orchards on assemblages in natural habitats can be variable, but predictable when using species habitat specificity in conjunction with a metacommunity framework. High intensity orchards may act as sink habitats, especially for species that readily disperse between crop and natural habitats. Here we recommend that local buffer strips are > 85 m wide, which will reduce the influence of cultural species spillover on sensitive natural ecosystems.

scholarly journals The Habitat Amount Hypothesis implies negative effects of habitat fragmentation on species richness and occurrence

2020 ◽  
Author(s):  
Santiago Saura
Keyword(s):  
Species Richness ◽  
Habitat Fragmentation ◽  
Spatial Configuration ◽  
Spatial Scales ◽  
Conservation Strategies ◽  
Negative Effects ◽  
Habitat Amount ◽  
Habitat Configuration ◽  
Habitat Amount Hypothesis ◽  
Individual Site

AbstractThe Habitat Amount Hypothesis (HAH) predicts that species richness, abundance or occurrence in a habitat site increases with the amount of habitat in the ‘local landscape’ defined by an appropriate distance around the site, with no distinct effects of the size of the habitat patch in which the site is located. It has been stated that a consequence of the HAH, if supported, would be that it is unnecessary to consider habitat configuration to predict or manage biodiversity patterns, and that conservation strategies should focus on habitat amount regardless of fragmentation. Here, I assume that the HAH holds and apply the HAH predictions to all habitat sites over entire landscapes that have the same amount of habitat but differ in habitat configuration. By doing so, I show that the HAH actually implies clearly negative effects of habitat fragmentation, and of other spatial configuration changes, on species richness, abundance or occurrence in all or many of the habitat sites in the landscape, and that these habitat configuration effects are distinct from those of habitat amount in the landscape. I further show that, contrary to current interpretations, the HAH is compatible with a steeper slope of the species-area relationship for fragmented than for continuous habitat, and with higher species richness or abundance for a single large patch than for several small patches with the same total area (SLOSS). This suggests the need to revise the ways in which the HAH has been interpreted and can be actually tested. The misinterpretation of the HAH has arisen from confounding and overlooking the differences in the spatial scales involved: the individual habitat site at which the HAH gives predictions, the local landscape around an individual site, and the landscapes or regions (with multiple habitat sites and different local landscapes) that need to be analysed and managed. The HAH has been erroneously viewed as negating or diminishing the relevance of fragmentation effects, while it actually supports the importance of habitat configuration for biodiversity. I conclude that, even in the cases where the HAH holds, habitat fragmentation and configuration are important for understanding and managing species distributions in the landscape.

scholarly journals Hymenopteran Parasitoid Diversity & Tri-Trophic Interactions: the Effects of Habitat Fragmentation in Wellington, New Zealand

2021 ◽  
Author(s):  
◽  
Franz-Rudolf Schnitzler
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
New Zealand ◽  
Habitat Fragmentation ◽  
Plant Species ◽  
Plant Species Richness ◽  
Forest Fragment ◽  
Plant Richness ◽  
Parasitoid Community ◽  
Parasitism Rates

<p>Habitat fragmentation and the resulting decline in biodiversity through the loss of habitat are thought to be the main threat to insect extinctions. According to the trophic level hypothesis, habitat fragmentation affects parasitoids more severely than their herbivorous hosts. Parasitoids also may be correlated with plant species richness, because plants host a variety of phytophagous insects acting as hosts for parasitoids, or plants provide food or act as shelter for parasitoids. In this study, the effects of the forest fragment properties; area, isolation, percentage of residential area surrounding focal fragments and plant richness on parasitic wasps and their interactions were examined. These fragmentation effects were examined in 10 urban native bush remnants in the Wellington and Hutt Valley region of the lower North Island, New Zealand. Fragmentation effects on species abundance, richness and diversity and on community assemblages were examined for the wasp families Ichneumonidae, Pompilidae and Proctotrupidae. Correlations between beta diversity of the plant community and the parasitoid community were analysed and the study investigated whether individual parasitoid occurrences can be predicted by the range of their host's host plants. This study focused on interactions between the kawakawa moth larva Cleora scriptaria, its primary host plant Macropiper excelsum and the parasitism rates by two parasitoids Aleiodes declanae (an endemic species) and Meteorus pulchricornis (an exotic species) and the herbivory caused by C. scriptaria larvae. In addition to interaction responses to forest fragmentation properties, interaction responses were also examined with respect to the properties of the plot and individual plant. Individual species showed different trends in response to the fragmentation properties, making interpretation of a general community response difficult. The abundance, richness and diversity of small-bodied parasitoids were inversely related to increasing area and plant species richness. Parasitoid community composition changed with fragment isolation and plant species richness. Ichneumonidae strongly responded to isolation in one year, whereas the Pompilidae responded to plant species richness. The Proctotrupidae community structure showed no response to any of the fragmentation properties. Correlations between plant and parasitoid community structures were not significant and individual parasitoid-plant associations were weak and inconclusive. Parasitism rates for A. declanae were significantly higher in more isolated fragments with smaller trees, and were negatively affected by overall parasitism rates, more so in isolated fragments. Parasitism rates by M. pulchricornis responded positively to larval densities and declined with increasing plant richness. Herbivory was positively related to the abundance of M. excelsum, tree size and larval density. The current study provides evidence that the forest fragment properties examined are, on their own, not always sufficient predictors of community structure and interactions for parasitoids. Aspects of the results from this thesis conflict with the trophic-level hypothesis with species responding in a negative or positive way, or not responding at all to forest fragmentation effects. The findings of this thesis support to conserving species diversity by maintaining and enhancing all types of existing forest fragments to prevent species extinctions.</p>

scholarly journals Decapod crustaceans associated with an artificial reef (Adriatic Sea)

2013 ◽  
Vol 14 (3) ◽  
pp. 64 ◽  
Author(s):  
A. SANTELLI ◽  
E. PUNZO ◽  
G. SCARCELLA ◽  
P. STRAFELLA ◽  
A. SPAGNOLO ◽  
...  
Keyword(s):  
Species Richness ◽  
New Species ◽  
Adriatic Sea ◽  
Benthic Communities ◽  
Natural Habitat ◽  
Artificial Reef ◽  
Artificial Substrates ◽  
Decapod Crustaceans ◽  
Soft Bottom ◽  
Abundance And Diversity

The aim of this study is to increase the knowledge on the distribution of decapod crustaceans associated with an artificial reef positioned on sandy-mud bottoms in the central Adriatic Sea. The reef is constituted of concrete modules assembled in pyramids and concrete poles. Hard and soft bottom samples were collected from 2001, just after reef construction, to 2005 (4 surveys per year). Regarding the soft seabed, three sites close to a pyramid, three inside the reef area at a distance of 10-15 m from the structures, and three 200 m outside the reef (control sites) were randomly sampled during each survey. At the same time, three pyramids (vertical and horizontal walls) and three poles were also investigated. After taxonomical analysis, decapod crustaceans were analysed using abundance and species richness. Sites and years were compared using a balanced, fixed effect, 2-way ANOVA and PERMANOVA. In addition, SIMPER analysis was performed to identify those species typifying each community inhabiting both the soft bottom and the artificial substrates. The results showed that the artificial reef induced an increase in both abundance and diversity of the decapods of the natural habitat. In fact, man-made substrates may offer new available space for biological colonization and allow the settlement of new species usually living on hard bottoms, thus increasing the complexity of the original benthic communities.

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