Search results for "DIVERSITE"
showing 10 items of 180 documents
Solar PAR and UVR modify the community composition and photosynthetic activity of sea ice algae
2015
The effects of increased photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) on species diversity, biomass and photosynthetic activity were studied in fast ice algal communities. The experimental set-up consisted of nine 1.44 m(2) squares with three treatments: untreated with natural snow cover (UNT), snow-free (PAR + UVR) and snow-free ice covered with a UV screen (PAR). The total algal biomass, dominated by diatoms and dinoflagellates, increased in all treatments during the experiment. However, the smaller biomass growth in the top 10-cm layer of the PAR + UVR treatment compared with the PAR treatment indicated the negative effect of UVR. Scrippsiella complex (mainly…
Management diversity begets biodiversity in production forest landscapes
2022
How to manage forest for biodiversity conservation is an ongoing debate. We argue that maximizing biodiversity in managed forest landscapes requires a diversity of forest management regimes in space and time. This will generate high levels of habitat heterogeneity at a landscape scale, which in turn will support various groups of forest species. Based on concepts from landscape ecology, we formulate five hypotheses on how management diversity, i.e. combining various management approaches can benefit overall biodiversity across a production forest landscape. First, management diversity will increase habitat diversity and, therefore, beta diversity (the habitat diversity hypothesis). Second, …
Mammal assemblage composition predicts global patterns in emerging infectious disease risk
2021
Abstract As a source of emerging infectious diseases, wildlife assemblages (and related spatial patterns) must be quantitatively assessed to help identify high‐risk locations. Previous assessments have largely focussed on the distributions of individual species; however, transmission dynamics are expected to depend on assemblage composition. Moreover, disease–diversity relationships have mainly been studied in the context of species loss, but assemblage composition and disease risk (e.g. infection prevalence in wildlife assemblages) can change without extinction. Based on the predicted distributions and abundances of 4466 mammal species, we estimated global patterns of disease risk through …
Contrasting Effects of Chronic Anthropogenic Disturbance on Activity and Species Richness of Insectivorous Bats in Neotropical Dry Forest
2022
For prioritizing conservation actions, it is vital to understand how ecologically diverse species respond to environmental change caused by human activity. This is particularly necessary considering that chronic human disturbance is a threat to biodiversity worldwide. Depending on how species tolerate and adapt to such disturbance, ecological integrity and ecosystem services will be more or less affected. Bats are a species-rich and functionally diverse group, with important roles in ecosystems, and are therefore recognized as a good model group for assessing the impact of environmental change. Their populations have decreased in several regions, especially in the tropics, and are threatene…
Biofonctionnements des sols tropicaux et mode de gestion des terres
2000
L'effet de deux peuplements de nématodes phytoparasites a été étudié en conditions contrôlées sur la croissance du mil (#Pennisetum glaucum$). Les plants de mil (cv. IKMV 8201) ont été cultivés en pots sur du col collecté au Sud du Sénégal dans un champ cultivé (sol cultivé) et dans une jachère de 17 ans (sol de jachère). La moitié du sol de chacun des prélèvements à été stérilisée. Pour compenser l'effet de la stérilisation, six cycles de cultures de mil de deux mois ont été faits avant l'expérimentation. A l'issu de cette période, trois espèces ont été observées sur le sol cultivé non stérilisé : #Scutellonema cavanessi$, #Tylenchorhynchus gladiolatus$ et #Ditylenchus myceliophagus$, dans…
L'acacia au Sénégal
1996
La biodiversité des Glomales associés à #Acacia albida$ est étudiée en fonction de l'âge de l'arbre, des saisons et des propriétés physicochimiques du sol. Les Glomales sont récoltées jusqu'à 1,5 et 4,5 m dans les régions soudano-guinéennes et jusqu'à 16 et 35 m dans les régions sahéliennes. La culture in vitro de la forme intraracinaire des Glomales en présence de racines isolées a montré une diversité morphologique des souches. En complément à cette taxonomie morphologique, des marqueurs moléculaires ont permis d'étudier la variabilité génétique des Glomales en comparant les variations de séquences d'ADN extrait de spores et de fragments mycorhiziens. (Résumé d'auteur)
Catastrophic effects of sand mining on macroinvertebrates in a large shallow lake with implications for management
2019
Sand mining is a human activity that is increasing in inland waters and has profound effects on entire aquatic ecosystems. However, current knowledge of the effects of sand mining on freshwater lake ecosystems remains limited, especially for biotic communities. Here, we investigated the responses of macroinvertebrates to indiscriminate sand mining in a large shallow lake of China. Our results indicated that sand mining significantly increased the content of suspended particulate matter, total nitrogen, total phosphorus and chlorophyll a in the water column both in the sand mining area and the area adjacent to the dredging activities. While there was significantly lower total nitrogen and th…
Climate change reshuffles northern species within their niches
2022
Climate change is a pervasive threat to biodiversity. While range shifts are a known consequence of climate warming contributing to regional community change, less is known about how species' positions shift within their climatic niches. Furthermore, whether the relative importance of different climatic variables prompting such shifts varies with changing climate remains unclear. Here we analysed four decades of data for 1,478 species of birds, mammals, butterflies, moths, plants and phytoplankton along a 1,200 km high latitudinal gradient. The relative importance of climatic drivers varied non-uniformly with progressing climate change. While species turnover among decades was limited, the …
Community Turnover of Wood-Inhabiting Fungi across Hierarchical Spatial Scales
2014
For efficient use of conservation resources it is important to determine how species diversity changes across spatial scales. In many poorly known species groups little is known about at which spatial scales the conservation efforts should be focused. Here we examined how the community turnover of wood-inhabiting fungi is realised at three hierarchical levels, and how much of community variation is explained by variation in resource composition and spatial proximity. The hierarchical study design consisted of management type (fixed factor), forest site (random factor, nested within management type) and study plots (randomly placed plots within each study site). To examine how species richne…
The effect of peatland drainage and restoration on Odonata species richness and abundance
2015
Background Restoration aims at reversing the trend of habitat degradation, the major threat to biodiversity. In Finland, more than half of the original peatland area has been drained, and during recent years, restoration of some of the drained peatlands has been accomplished. Short-term effects of the restoration on peatland hydrology, chemistry and vegetation are promising but little is known about how other species groups apart from vascular plants and bryophytes respond to restoration efforts. Results Here, we studied how abundance and species richness of Odonata (dragonflies and damselflies) respond to restoration. We sampled larvae in three sites (restored, drained, pristine) on each o…