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Displaying 1241 - 1245 of 1605Relative pollen productivity estimates of major anemophilous taxa and relevant source area of pollen in a cultural landscape of the hemi-boreal forest zone (Estonia)
Estimates of relevant source area of pollen (RSAP) and relative pollen productivity (PPE) are critical parameters for quantitative reconstructions of past vegetation and land cover. This study provides estimates for PPE relative to Poaceae for ten taxa, characterizing the cultural landscape of south Estonia and the RSAP for 40 lakes with an average radius of approximately 100m (22–274m, average 101m) in the region. We evaluate the effects on those estimates of various combinations of factors, such as the analytical methods (i.e.
Design of ecoregional monitoring in conservation areas of high-latitude ecosystems under contemporary climate change
Land ownership in Alaska includes a mosaic of federally managed units. Within its agency’s context, each unit has its own management strategy, authority, and resources of conservation concern, many of which are migratory animals. Though some units are geographically isolated, many are nevertheless linked by paths of abiotic and biotic flows, such as rivers, air masses, flyways, and terrestrial and aquatic migration routes.
Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in a temperate re-connected floodplain
The relative magnitudes of, and factors controlling, denitrification and dissimilatory nitrate reduction to ammonium (DNRA) were measured in the soil of a re-connected temperate floodplain divided into four different land management zones (grazing grassland, hay meadow, fritillary meadow and a buffer zone). Soil samples were collected from each zone to measure their respective potentials for nitrate attenuation using ¹⁵N both at the surface and at depth in the soil column and additional samples were collected to measure the lability of the organic carbon.
Developing effective sampling designs for monitoring natural resources in Alaskan national parks: An example using simulations and vegetation data
Monitoring natural resources in Alaskan national parks is challenging because of their remoteness, limited accessibility, and high sampling costs. We describe an iterative, three-phased process for developing sampling designs based on our efforts to establish a vegetation monitoring program in southwest Alaska. In the first phase, we defined a sampling frame based on land ownership and specific vegetated habitats within the park boundaries and used Path Distance analysis tools to create a GIS layer that delineated portions of each park that could be feasibly accessed for ground sampling.
Cross-fence comparisons: Theory for spatially comprehensive, controlled variable assessment of treatment effects in managed landscapes
Historically monitoring of grazing impacts in rangelands has been seriously compromised by the small area, infrequency and variability of field-based sampling plots. Remote sensing of vegetation cover, which can be a surrogate for overall ecosystem condition, permits adequate spatial and temporal monitoring of land condition but can still be compromised by considerable inter and intra-paddock (field) variability. Cross-fence sample pairs control for local clines and patchiness in spatial and temporal variables such as vegetation, landform, soil type, surface-flows, and rainfall.