Passar para o conteúdo principal

page search

Displaying 1525 - 1536 of 2218

Integration of multi-sensor data to assess grassland dynamics in a Yellow River sub-watershed

Journal Articles & Books
Dezembro, 2012

Grasslands form the dominant land cover in the upper reaches of the Yellow River and provide a reliable indicator by being strongly correlated with regional terrestrial ecological status. Remote sensing can provide information useful for vegetation quality assessments, but no single sensor can meet the needs for the high temporal–spatial resolution required for such assessments on a watershed scale.

Measuring Natural Pest Suppression at Different Spatial Scales Affects the Importance of Local Variables

Journal Articles & Books
Dezembro, 2012

The role biodiversity plays in the provision of ecosystem services is widely recognized, yet few ecological studies have identified characteristics of natural systems that support and maintain ecosystem services. The purpose of this study was to identify landscape variables correlated with natural pest suppression carried out by arthropod natural enemies, predators and parasitoids. We conducted two field experiments, one observational and one experimental, where landscape variables at broad and local scales were measured and related to natural pest suppression.

Adoption of Policy Incentives and Land Use: Lessons From Frontier Agriculture in Southeastern Peru

Journal Articles & Books
Dezembro, 2012

Literature on environmental change often highlights the importance of public policies as a key driver of land use and land cover change. However, demonstration of policy impacts in agricultural settings has been hampered by the lack of systematic analysis across landholders, who may not universally adopt government policy incentives, or time periods, which may be associated with differing policy regimes.

Comparative Investigation of Image Fusion in the Context of Classification

Journal Articles & Books
Dezembro, 2012
Índia

Image fusion assists in visual interpretation, mapping, change detection and many other applications. Multispectral and Panchromatic images are fused to produce images having enhanced spatial and spectral properties. These properties are generally distorted from original images. The aim of this paper is to identify the effectiveness of the several fusion techniques based on the distortions and applications.

Objective classification of air quality monitoring sites over Europe

Journal Articles & Books
Dezembro, 2012
Europa

The observation sites that make up air quality monitoring networks can have very different characteristics (topography, climatology, distance to emission sources, etc), which are partially described in the meta-information provided with data sets. At the scale of Europe, the description of the sites depends on the institute(s) in charge of the air quality monitoring in each country, and is based on specific criteria that can be sometimes rather subjective.

Shifting cultivation effects on creek water quality around Barkal Upazila in Chittagong Hill Tracts, Bangladesh

Journal Articles & Books
Dezembro, 2012
Bangladesh

We report the effects of shifting cultivation on water quality in 16 creeks investigated once in 2007 and twice in 2008 in 16 apparently similar small neighboring watersheds, each of 3 to 5 ha, at four locations around Barkal sub-district under Rangamati District of Chittagong Hill Tracts in Bangladesh. Concentrations of SO₄ ²⁻ and K⁺, and pH in creek water were lower, and NO₃-N and Na⁺ concentrations were higher in shifting-cultivation land compared to land with either plantation or natural forest or a combination of these cover types.

Sensitivity of predicted pollutant levels to urbanization in China

Journal Articles & Books
Dezembro, 2012
China

Urbanization in China accompanies economic development and population growth. Changes in land use leads to changes in both meteorological and chemical fields. In this study, the impact of land use change in Jing-Jin-Ji (JJJ, indicating Beijing–Tianjin–Hebei) and Yangtze River Delta (YRD) areas on meteorology and ozone concentrations are studied using the WRF–Chem model. Land use change is represented by two different land cover data sets: USGS and MODIS.

Detection and analysis of land-use and land-cover changes in the Midwest escarpment of the Ethiopian Rift Valley

Journal Articles & Books
Dezembro, 2012

This study detects patterns of land-use and land-cover changes in the last three decades (1972–2004) and analyses its causative factors in the Upper Dijo River catchment, Midwest escarpment of Ethiopian Rift Valley. Data captured through the synergy of an aerial photo, satellite image and ground-based socio-economic survey were analysed by GIS and SPSS. The results showed a decline in shrub-grassland and riverine trees at 21.5 and 16.3 ha per year, respectively, and increase in plantation trees, annual crops and bare/open grasslands at 2.8, 12.5 and 24.8 ha per year, respectively.

Estimating urban vegetation cover fraction using Google Earth® images

Journal Articles & Books
Dezembro, 2012
Estados Unidos

We exploited publicly available satellite- and aircraft-based imagery to estimate urban vegetation cover fraction and land use by class for a semiarid urban area that includes Phoenix, AZ, USA, using low-cost and technologically modest tools. This technique is also used to evaluate two satellite-derived tree cover datasets as well as to compare estimates from the present study with land cover data generated from another study performed using the same study domain.

Local landscape composition and configuration around North American Breeding Bird Survey routes: Ecological Archives E093‐215

Journal Articles & Books
Dezembro, 2012

Large‐scale monitoring of avian species is often conducted by observers driving rural roads and highways. Surveys along roads allow for easy and reliable access over time and the ability to survey large geographic areas in a relatively short period of time. However, if the landscape directly adjacent to these roadside transects is not representative of the greater landscape inhabited by the bird species, then estimates of abundance along the route may not be accurate for the greater landscape.

Can active restoration of tropical rainforest rescue biodiversity? A case with bird community indicators

Journal Articles & Books
Dezembro, 2012

There is vigorous debate about the potential for reforestation to offset losses in biodiversity associated with tropical deforestation, but a scarcity of good data. We quantified developmental trajectories following active restoration (replanting) of deforested pasture land to tropical Australian rainforest, using 20 different bird community indicators within chronosequences of multiple sites. Bird species composition in restored sites (1–24years old) was intermediate between that of reference sites in pasture and primary rainforest.

global land-cover validation data set, part I: fundamental design principles

Journal Articles & Books
Dezembro, 2012

A number of land-cover products, both global and regional, have been produced and more are forthcoming. Assessing their accuracy would be greatly facilitated by a global validation database of reference sites that allows for comparative assessments of uncertainty for multiple land-cover data sets. We propose a stratified random sampling design for collecting reference data.