Biotic interactions Research Papers - Academia.edu (original) (raw)

In the last two decades, interest in species distribution models (SDMs) of plants and animals has grown dramatically. Recent advances in SDMs allow us to potentially forecast anthropogenic effects on patterns of biodiversity at different... more

In the last two decades, interest in species distribution models (SDMs) of plants and animals has grown dramatically. Recent advances in SDMs allow us to potentially forecast anthropogenic effects on patterns of biodiversity at different spatial scales. However, some limitations still preclude the use of SDMs in many theoretical and practical applications. Here, we provide an overview of recent advances in this field, discuss the ecological principles and assumptions underpinning SDMs, and highlight critical limitations and decisions inherent in the construction and evaluation of SDMs. Particular emphasis is given to the use of SDMs for the assessment of climate change impacts and conservation management issues. We suggest new avenues for incorporating species migration, population dynamics, biotic interactions and community ecology into SDMs at multiple spatial scales. Addressing all these issues requires a better integration of SDMs with ecological theory.

Knowledge about the current distribution of threatened and/or understudied species is a fundamental component of conservation biology. Mapping species distributions based on recent known occurrences is particularly important for those... more

Knowledge about the current distribution of
threatened and/or understudied species is a fundamental
component of conservation biology. Mapping species distributions
based on recent known occurrences is particularly
important for those that are rare or declining. Too
often, cryptic species go undetected throughout parts of
their range, whereas others just receive less research
attention. We used contemporary presence data for the
Pallas’s cat (Otocolobus manul), a small cryptic felid, to
characterize potential rangewide and regional habitat for
the species and identify those abiotic and biotic variables
most influencing its distribution. Several regions lacking
contemporary occurrence records contain potential habitat
for Pallas’s cats, including the Koh-i-Baba Mountains of
Afghanistan, Qinghai-Tibetan Plateau, steppes of Inner
Mongolia, Kunlun Mountains of China, and Tian Shan and
Pamir Mountains of Kyrgyzstan, Tajikistan, and China.
Some of these areas have not been included in prior rangewide
distribution assessments. The distribution of pikas
(Ochotona spp.), small mammals that likely represent a
critical prey species everywhere they are sympatric, was
the most important factor affecting the Pallas’s cat’s distribution.
This suggests Pallas’s cats may be prey specialists,
and that pika presence and habitat are critical
considerations for future Pallas’s cat surveys and in the
development of regional conservation actions.

Distributions of plant species over the earth's surface are neither random nor even, but are geographic specific and characterized by specific sets of environmental and climatic factors. The current study aimed to classify the vegetation... more

Distributions of plant species over the earth's surface are neither random nor even, but are geographic specific and characterized by specific sets of environmental and climatic factors. The current study aimed to classify the vegetation along the River Panjkora of the district Dir Lower, Khyber-Pakhtunkhwa, Pakistan into different phytogeographic units via exercising the Multivariate statistical techniques. Vegetation sampling was carried out through quadrat quantitative ecological techniques. Quadrats of various sizes i.e. 1 × 1 m 2 , 5 × 5 m 2 and 10 × 10 m 2 were taken for herbs, shrubs and trees, respectively. Inclusively 215 plant species belong to 22 different phytogeographic elements were analysed and documented. The most dominant category of phytogeographic element was Irano-Turanian with 77 species, followed by Cosmopolitan 25 species, Holarctic 23 species, Pluriregional 19 species,

Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small-scale studies on herbivore effects on aquatic plants,... more

Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small-scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquatic ecosystems. Our current knowledge of the regulation of primary producers has hindered efforts to understand the structure and functioning of aquatic ecosystems, and to manage such ecosystems effectively. We conducted a global meta-analysis of the outcomes of plant–herbivore interactions using a data set comprised of 326 values from 163 studies, in order to test two mechanistic hypotheses: first, that greater negative changes in plant abundance would be associated with higher herbivore biomass densities; second, that the magnitude of changes in plant abundance would vary with herbivore taxonomic identity. We found evidence that plant abundance declined with increased herbivore density, with plants eliminated at high densities. Significant between-taxa differences in impact were detected, with insects associated with smaller reductions in plant abundance than all other taxa. Similarly, birds caused smaller reductions in plant abundance than echinoderms, fish, or molluscs. Furthermore, larger reductions in plant abundance were detected for fish relative to crustaceans. We found a positive relationship between herbivore species richness and change in plant abundance, with the strongest reductions in plant abundance reported for low herbivore species richness, suggesting that greater herbivore diversity may protect against large reductions in plant abundance. Finally, we found that herbivore–plant nativeness was a key factor affecting the magnitude of herbivore impacts on plant abundance across a wide range of species assemblages. Assemblages comprised of invasive herbivores and native plant assemblages were associated with greater reductions in plant abundance compared with invasive herbivores and invasive plants, native herbivores and invasive plants, native herbivores and mixed-nativeness plants, and native herbivores and native plants. By contrast, assemblages comprised of native herbivores and invasive plants were associated with lower reductions in plant abundance compared with both mixed-nativeness herbivores and native plants, and native herbivores and native plants. However, the effects of herbivore–plant nativeness on changes in plant abundance were reduced at high herbivore densities. Our mean reductions in aquatic plant abundance are greater than those reported in the literature for terrestrial plants, but lower than aquatic algae. Our findings highlight the need for a substantial shift in how biologists incorporate plant–herbivore interactions into theories of aquatic ecosystem structure and functioning. Currently, the failure to incorporate top-down effects continues to hinder our capacity to understand and manage the ecological dynamics of habitats that contain aquatic plants.

Forest structure and composition have been used to assess the habitat characteristics that determine bird distributions. The patterns of distribution have been shaped by historical and ecological factors that play different roles at both... more

Forest structure and composition have been used to assess the habitat characteristics that determine bird distributions. The patterns of distribution have been shaped by historical and ecological factors that play different roles at both temporal and spatial scales. The objectives of this research were to characterize the habitat of the endangered Military Macaw (Ara militaris) and evaluate the potential distribution of this species based on trends of land use changes in Mexico. We characterized the community structure and floristic composition of 8 forests that are currently used by the Military Macaw for breeding and feeding and compared the results with 6 similar forests characterized in other studies but without historical records of the presence of the Military Macaw. The Military Macaw preferred sites with high diversity of plant species dominated by trees from 4 to 15 m in height and from 5 to 90 cm in diameter at breast height. We identified 236 plant species in the 8 forests with 20 species (8.4%) used for nesting and feeding by the Military Macaw. The floristic
composition is important for the presence of the Military Macaw because there were significant differences between forests with and without its presence. The potential area of distribution of the Military Macaw had decreased by 32% and the remnant areas are included in only 8 National Protected Areas. The protected areas of natural forests should be increased to preserve the sites of potential distribution and consequently the habitat of the Military Macaw in Mexico.

This paper discusses biotic interactions in agroecosystems and how they may be manipulated to support crop productivity and environmental health by provision of ecosystem services such as weed, pest and disease management, nutrient... more

This paper discusses biotic interactions in agroecosystems and how they may be manipulated to support crop productivity and environmental health by provision of ecosystem services such as weed, pest and disease management, nutrient cycling and biodiversity conservation. Important elements for understanding biotic interactions include consideration of the effects of diversity, species composition and food web structure on ecosystem processes; the impacts of timing, frequency and intensity of disturbance; and the importance of multitrophic interactions. All of these elements need to be considered at multiple scales that depend in part on the range of the movement of the organisms involved. These issues are first discussed in general, followed by an examination of the application of these concepts in agricultural management. The potential for a greater use of ecological management approaches is high; however, owing to the nature of complex interactions in ecosystems, there is some inhe...

Worldwide, the most species rich plant communities at small scale (< 10 m2 grid) are some types of temperate grassland communities, and of these, the calcareous grasslands of temperate Europe are the most diverse. Calcareous grasslands... more

Worldwide, the most species rich plant communities at small scale (< 10 m2 grid) are some types of temperate grassland communities, and of these, the calcareous grasslands of temperate Europe are the most diverse. Calcareous grasslands were once widespread in the hilly calcareous regions of Western Europe but due to changes in agricultural practices (either intensification or abandonment of grazing by sheep and cattle, and the consequent succession towards forest) their extent has decreased dramatically and the remaining ...