Search results for "LAND"
showing 10 items of 9939 documents
Net ammonification as influenced by plant diversity in experimental grasslands
2012
Abstract Previous plant diversity experiments have mainly reported positive correlations between diversity and N mineralization. We tested whether this relationship can be explained by plant diversity-induced changes i) in the quantity or quality of organic matter or ii) in microclimatic conditions of central European grassland mixtures. We measured ex-situ net ammonification in a laboratory incubation of aboveground plant material and soil sampled in differently diverse plant mixtures. Secondly, in-situ net ammonification was assessed in a field incubation with mineralization cores containing standardized material in four treatments: soil only (control), and soil mixed with field-fresh pla…
Soil feedback on plant growth in a sub-arctic grassland as a result of repeated defoliation
2008
In the long term, defoliation of plants can be hypothesized to decrease plant carbon supply to soil decomposers and thus decrease decomposer abundance and nutrient mineralization in the soil. To test whether defoliation creates changes in soil that can feedback to plant growth, we collected soil from sub-arctic grassland plots that had been either defoliated or non-defoliated for three years and followed the growth of different plant species combinations in these soils in greenhouse conditions. Plant N acquisition and plant growth were lower in the soil collected from the defoliated field plots than in the soil collected from the non-defoliated plots. This response did not depend on the spe…
Defoliation and patchy nutrient return drive grazing effects on plant and soil properties in a dairy cow pasture
2009
Large herbivores can influence plant and soil properties in grassland ecosystems, but especially for belowground biota and processes, the mechanisms that explain these effects are not fully understood. Here, we examine the capability of three grazing mechanisms-plant defoliation, dung and urine return, and physical presence of animals (causing trampling and excreta return in patches)-to explain grazing effects in Phleum pratense-Festuca pratensis dairy cow pasture in Finland. Comparison of control plots and plots grazed by cows showed that grazing maintained original plant-community structure, decreased shoot mass and root N and P concentrations, increased shoot N and P concentrations, and …
50,000 years of ice and seals: Impacts of the Last Glacial Maximum on Antarctic fur seals
2021
Abstract Ice is one of the most important drivers of population dynamics in polar organisms, influencing the locations, sizes, and connectivity of populations. Antarctic fur seals, Arctocephalus gazella, are particularly interesting in this regard, as they are concomitantly reliant on both ice‐associated prey and ice‐free coastal breeding areas. We reconstructed the history of this species through the Last Glacial Maximum (LGM) using genomic sequence data from seals across their range. Population size trends and divergence events were investigated using continuous‐time size estimation analysis and divergence time estimation models. The combined results indicated that a panmictic population …
Diversity and endemism of woody plant species in the Equatorial Pacific seasonally dry forests
2009
The biodiversity hotspot of the Equatorial Pacific region in western Ecuador and northwestern Peru comprises the most extensive seasonally dry forest formations west of the Andes. Based on a recently assembled checklist of the woody plants occurring in this region, we analysed their geographical and altitudinal distribution patterns. The montane seasonally dry forest region (at an altitude between 1,000 and 1,100 m, and the smallest in terms of area) was outstanding in terms of total species richness and number of endemics. The extensive seasonally dry forest formations in the Ecuadorean and Peruvian lowlands and hills (i.e., forests below 500 m altitude) were comparatively much more specie…
Interactions between Climate Change and Infrastructure Projects in Changing Water Resources: An Ethnobiological Perspective from the Daasanach, Kenya
2021
The fast and widespread environmental changes that have intensified in the last decades are bringing disproportionate impacts to Indigenous Peoples and Local Communities. Changes that affect water resources are particularly relevant for subsistence-based peoples, many of whom already suffer from constraints regarding reliable access to safe water. Particularly in areas where water is scarce, climate change is expected to amplify existing stresses in water availability, which are also exacerbated by multiple socioeconomic drivers. In this paper, we look into the local perceptions of environmental change expressed by the Daasanach people of northern Kenya, where the impacts of climate change …
Understanding the long-term effects of species invasions
2006
We describe here the ecological and evolutionary processes that modulate the effects of invasive species over time, and argue that such processes are so widespread and important that ecologists should adopt a long-term perspective on the effects of invasive species. These processes (including evolution, shifts in species composition, accumulation of materials and interactions with abiotic variables) can increase, decrease, or qualitatively change the impacts of an invader through time. However, most studies of the effects of invasive species have been brief and lack a temporal context; 40% of recent studies did not even state the amount of time that had passed since the invasion. Ecologists…
Conservation of the Grey Bush Cricket Platycleis albopunctata (Orthoptera: Tettigoniidae) Under Differing Habitat Conditions: Implications From an In…
2009
Assessing the chance of survival of any species is a great challenge in conservation biology. In this chapter, we analyse the vulnerability of the grey bush cricket Platycleis albopunctata in habitats of different food availability under current and increased temperature conditions applying an individual-based model. Our simulations show that populations in warmer habitats with a higher food limitation have a much lower extinction risk than those living in habitats that are less food-limited and colder. An increase in mortalities of life stages severely increases the risk of population extinction, whereas a shift in the termination of egg diapause towards the beginning of the year caused by…
Variability and cryptic heteromorphism of Ambrosia artemisiifolia seeds: What consequences for its invasion in France
2007
International audience; Background and Aims:Ambrosia artemisiifolia is a ruderal weed introduced from North America to Europe. It produces large amount of achenes which are highly heterogeneous in size. Due to the preponderant role of propagules in invasive plant processes, the achene mass variability related to germination, dispersal strategy and life history traits of offspring were investigated within this species. Methods:The variability in achene mass was quantified among six populations sampled in different habitats. The effects of achene mass variation on germination were studied. The percentages of floating and non-floating achenes were evaluated in the studied populations. The cons…
First estimates of metabolic rate in Atlantic bluefin tuna larvae.
2020
Atlantic bluefin tuna is an iconic scombrid species with a high commercial and ecological value. Despite their importance, many physiological aspects, especially during the larval stages, are still unknown. Metabolic rates are one of the understudied aspects in scombrid larvae, likely due to challenges associated to larval handling before and during respirometry trials. Gaining reliable estimates of metabolic rates is essential to understand how larvae balance their high growth needs and activity and other physiological functions, which can be very useful for fisheries ecology and aquaculture. This is the first study to (a) estimate the relationship between routine metabolic rate (RMR) and …