Landscape Ecology - Landscape archaeology has a lot to offer to landscape ecology, being an interdisciplinary approach that emphasizes the study of long-term human–environment dynamics. We... 相似文献
Landscape Ecology - Landscape ecology early on developed the awareness that central objects of investigation are not stable over time and therefore the historical dimension must be included, or at... 相似文献
Conservation for the Indiana bat (Myotis sodalis), a federally endangered species in the United States of America, is typically focused on local maternity sites; however, the species is a regional migrant, interacting with the environment at multiple spatial scales. Hierarchical levels of management may be necessary, but we have limited knowledge of landscape-level ecology, distribution, and connectivity of suitable areas in complex landscapes.
Objectives
We sought to (1) identify factors influencing M. sodalis maternity colony distribution in a mosaic landscape, (2) map suitable maternity habitat, and (3) quantify connectivity importance of patches to direct conservation action.
Methods
Using 3 decades of occurrence data, we tested a priori, hypothesis-driven habitat suitability models. We mapped suitable areas and quantified connectivity importance of habitat patches with probabilistic habitat availability metrics.
Results
Factors improving landscape-scale suitability included limited agriculture, more forest cover, forest edge, proximity to medium-sized water bodies, lower elevations, and limited urban development. Areas closer to hibernacula and rivers were suitable. Binary maps showed that 30% of the study area was suitable for M. sodalis and 29% was important for connectivity. Most suitable patches were important for intra-patch connectivity and far fewer contributed to inter-patch connectivity.
Conclusions
While simple models may be effective for small, homogenous landscapes, complex models are needed to explain habitat suitability in large, mixed landscapes. Suitability modeling identified factors that made sites attractive as maternity areas. Connectivity analysis improved our understanding of important areas for bats and prioritized areas to target for restoration.
Stream fish distributions are commonly linked to environmental disturbances affecting terrestrial landscapes. In Great Plains prairie streams, the independent and interactive effects of watershed impoundments and land cover changes remain poorly understood despite their prevalence and assumed contribution to declining stream fish diversity. We used structural equation models and fish community samples from third‐order streams in the Kansas River and Arkansas River basins of Kansas, USA to test the simultaneous effects of geographic location, terrestrial landscape alteration, watershed impoundments and local habitat on species richness for stream‐associated and impoundment‐associated habitat guilds. Watershed impoundment density increased from west to east in both basins, while per cent altered terrestrial landscape (urbanisation + row‐crop agriculture) averaged ~50% in the west, declined throughout the Flint Hills ecoregion and increased (Kansas River basin ~80%) or decreased (Arkansas River basin ~30%) to the east. Geographic location had the strongest effect on richness for both guilds across basins, supporting known zoogeography patterns. In addition to location, impoundment species richness was positively correlated with local habitat in both basins; whereas stream‐species richness was negatively correlated with landscape alterations (Kansas River basin) or landscape alterations and watershed impoundments (Arkansas River basin). These findings suggest that convergences in the relative proportions of impoundment and stream species (i.e., community structure) in the eastern extent of both basins are related to positive effects of increased habitat opportunities for impoundment species and negative effects caused by landscape alterations (Kansas River basin) or landscape alterations plus watershed impoundments (Arkansas River basin) for stream species. 相似文献
Fish eggs and larvae are often subject to very high mortality, and variation in early life survival can be important for population dynamics. Although longnose suckers (Catostomus catostomus) are widespread in northern North America, little is known about their early life history. We examined fecundity and early larval survivorship during sucker spawning events in three small Lake Michigan tributaries. Although egg deposition varied 25% among spawning events, estimated larval export to the lake varied over 25,000‐fold from around 1000 to 26 million. Based on variation in environmental conditions across years, it appears that spring flow and temperature may be important determinants of egg survival to larval outmigration. Larval age data suggest that most individuals that survived to outmigration hatched during a 2‐day period despite adult spawning across at least 10 days. Most larvae spent <2 weeks in the stream and emigrated around the time of transition from endogenous to exogenous feeding before substantial growth occurred. In two of three cases, larvae drifted exclusively at night; however, high drift rates occurred during both day and night in the case where larvae were very abundant, suggesting density‐dependent drift behaviour. Our results indicate that survival in tributary streams from egg deposition to larval export is highly variable in longnose suckers. These large differences in early life survival may translate into variability in recruitment, thereby influencing population structure and dynamics. 相似文献
It has been found that mechanical activation of amorphous carbon obtained from Katerina SV corn waste encourages formation of carbon nanotubes. At the same time, carbon tube output after 7 and 42 hours of mechanical activation is 11 and 42% by weight, respectively. 相似文献
The molecular analysis of the arbuscular mycorrhizal (AM) symbiosis started at the beginning of this decade. The paper summarises the work of the ‘Laboratorium für Molekulare Genetik arbuskulärer Mykorrhiza’ at the MPI für terrestrische Mikrobiologie in Marburg on three major topics. Firstly, the plant response to the mycorrhizal colonisation was analysed using both, targeted and non‐targeted approaches. As an example, the localisation of the gst1 mRNA in potato mycorrhiza is shown. Second, molecular techniques were established to analyse gene expression of the fungal partner of the symbiosis. We present a differential RNA display analysis of spore germination in two AM fungi and the cloning of a gene from Glomus mosseae that shows expression at all stages of the fungal life cycle. In the last part, we introduce the work we are carrying out with a new root endophytic fungus, Piriformospora indica. Infection experiments on maize showed that despite the fungus performs as a root necrotroph, it has a positive effect on plant growth. 相似文献
Reviewing the situation of quinoa production in southern Bolivia, Jacobsen (2011, J. Agron. Crop Sci. 197: 390) argues that the booming export market has a negative effect on the environment and on the home consumption of quinoa, thereby leading to an environmental disaster in the region. In view of the scarcity of scientific knowledge on the rapid social and environmental dynamics in the region, we consider that Jacobsen’s review misrepresents the situation of quinoa production in southern Bolivia. Specifically, we argue that (i) the data presented by Jacobsen (2011, J. Agron. Crop Sci. 197: 390) do not support any drop in quinoa crop yield supposed to reflect soil degradation and (ii) his demonstration regarding home consumption of quinoa is ill‐founded from both a nutritional and a cultural point of view. We suggest that the diffusion of the arguments exposed by Jacobsen (2011, J. Agron. Crop Sci. 197: 390), because of their flaws, might have strong negative impacts on those concerned with sustainable food production and fair‐trade with developing countries. We conclude that, rather than reinforced agro‐technical controls on local farmers, the rising competition in the international quinoa market requires a shift towards an ethical economy and ethical research cooperation with quinoa producers. 相似文献