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Particular Plant Species (particular + plant_species)
Selected AbstractsIndication of antagonistic interaction between climate change and erosion on plant species richness and soil properties in semiarid Mediterranean ecosystemsGLOBAL CHANGE BIOLOGY, Issue 2 2009PATRICIO GARCÍA-FAYOS Abstract We analyzed the consequences of climate change and the increase in soil erosion, as well as their interaction on plant and soil properties in semiarid Mediterranean shrublands in Eastern Spain. Current models on drivers of biodiversity change predict an additive or synergistic interaction between drivers that will increase the negative effects of each one. We used a climatic gradient that reproduces the predicted climate changes in temperature and precipitation for the next 40 years of the wettest and coldest end of the gradient; we also compared flat areas with 20° steep hillslopes. We found that plant species richness and plant cover are negatively affected by climate change and soil erosion, which in turn negatively affects soil resistance to erosion, nutrient content and water holding capacity. We also found that plant species diversity correlates weakly with plant cover but strongly with soil properties related to fertility, water holding capacity and resistance to erosion. Conversely, these soil properties correlate weaker with plant species cover. The joint effect of climate change and soil erosion on plant species richness and soil characteristics is antagonistic. That is, the absolute magnitude of change is smaller than the sum of both effects. However, there is no interaction between climate change and soil erosion on plant cover and their effects fit the additive model. The differences in the interaction model between plant cover and species richness supports the view that several soil properties are more linked to the effect that particular plant species have on soil processes than to the quantity and quality of the plant cover and biomass they support. Our findings suggest that plant species richness is a better indicator than plant cover of ecosystems services related with soil development and protection to erosion in semiarid Mediterranean climates. [source] Vegetation, environment, and time: The origination and termination of ecosystemsJOURNAL OF VEGETATION SCIENCE, Issue 5 2006Stephen T. Jackson Abstract Terrestrial ecosystems originate when particular plant species attain dominance at specific locations under specific environmental regimes. Ecosystems terminate, gradually or abruptly, when the dominant species or functional types are replaced by others, usually owing to environmental change or severe and irreversible disturbance. Assessing whether current ecosystems are sustainable in the face of future environmental change can be aided by examining the range of environmental variation those ecosystems have experienced in the past, and by determining the environmental conditions under which those ecosystems arose. The range of environmental variation depends on the time scale at which it is assessed. A narrow time span (e.g. 200,300 years) may underestimate the range of variation within which an ecosystem is sustainable, and it may also underestimate the risk of major transformation or disruption of that ecosystem by environmental change. Longer time spans (e.g. 1000,2000 years) increase the range of variation, by encompassing a larger sample of natural variability as well as non-stationary variability in the earth system. Most modern ecosystems disappear when the time span is expanded to 10000,15 000 years owing to secular changes in earth's climate system. Paleo-ecological records can pinpoint the time of origination of specific ecosystems, and paleo-environmental records can reveal the specific environmental changes that led to development of those ecosystems and the range of environmental variation under which those ecosystems have maintained themselves in the past. This information can help identify critical environmental thresholds beyond which specific modern ecosystems can no longer be sustained. [source] Rare species in communities of tropical insect herbivores: pondering the mystery of singletonsOIKOS, Issue 3 2000Vojtech Novotný The host specificity, taxonomic composition and feeding guild of rare species were studied in communities of herbivorous insects in New Guinea. Leaf-chewing and sap-sucking insects (Orthoptera, Phasmatodea, Coleoptera, Lepidoptera and Hemiptera-Auchenorrhyncha) were sampled from 30 species of trees and shrubs (15 spp. of Ficus, Moraceae, six spp. of Macaranga and nine species of other Euphorbiaceae) in a lowland rain forest. Feeding trials were performed with all leaf-chewers in order to exclude transient species. Overall, the sampling produced 80,062 individuals of 1050 species. The species accumulation curve did not attain an asymptote, despite 950 person-days of sampling. Rare species, defined as those found as single individuals, remained numerous even in large samples and after the exclusion of transient, non-feeding species. There was no difference among plant species in the proportion of rare species in their herbivore communities, which was, on average, 45%. Likewise, various herbivore guilds and taxa had all very similar proportions of rare and common species. There was also no difference between rare and common species in their host specificity. Both highly specialised species and generalists, feeding on numerous plants, contributed to the singleton records on particular plant species. Predominantly, a species was rare on a particular host whilst more common on other, often related, host species, or relatively rare on numerous other host plants, so that its aggregate population was high. Both cases are an example of the "mass effect", since it is probable that such rare species were dependent on a constant influx of immigrants from the other host plants. These other plants were found particularly often among congeneric plants, less so among confamilial plants from different genera and least frequently among plants from different families. There were also 278 very rare species, found as one individual on a single plant species only. Their host specificity could not be assessed; they might have been either very rare specialists, or species feeding also on other plants, those that were not studied. The former possibility is unlikely since monophagous species, collected as singletons at the present sampling effort, would have existed at an extremely low population density, less than 1 individual per 10 ha of the forest. [source] Recent developments in the molecular discrimination of formae speciales of Fusarium oxysporumPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2008Bart Lievens Abstract Rapid and reliable detection and identification of potential plant pathogens is required for taking appropriate and timely disease management measures. For many microbial species of which all strains generally are plant pathogens on a known host range, this has become quite straightforward. However, for some fungal species this is quite a challenge. One of these is Fusarium oxysporum Schlechtend:Fr., which, as a species, has a very broad host range, while individual strains are usually highly host-specific. Moreover, many strains of this fungus are non-pathogenic soil inhabitants. Thus, with regard to effective disease management, identification below the species level is highly desirable. So far, the genetic basis of host specificity in F. oxysporum is poorly understood. Furthermore, strains that infect a particular plant species are not necessarily more closely related to each other than to strains that infect other hosts. Despite these difficulties, recently an increasing number of studies have reported the successful development of molecular markers to discriminate F. oxysporum strains below the species level. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||