The vegetation dynamics of semi-arid and arid landscapes are temporally and spatially heterogeneous and subject to various disturbance regimes that act on decadal scales. Traditional field-based monitoring methods have failed to sample adequately in time and space in order to capture this heterogeneity and thus lack the spatial extent and the long-term continuous time series of data necessary to detect anomalous dynamics in landscape behavior. Time series of ecological indicators of land degradation that are collected synoptically from local to global spatial scales can be derived from the 33-year and continuing Landsat satellite archive. Consequently, a retrospective study was conducted on a commercially grazed sagebrush steppe dominated Utah landscape using a time series of standardized Landsat imagery for the period 1972 to 1997. The study had the objectives to (1) characterize and map the historical trends of a remotely-sensed index of vegetation response, a correlate of vegetation cover or phytomass, and (2) to retrospectively infer the cause of this response to historical records of grazing and wet and drought periods. A time series of dry season vegetation index maps were statistically clustered to generate a spatio-temporal map of three coarse trends of vegetation response, i.e., declining, stable, and increasing trends. This study showed that 71% of the landscape's locations had an increasing trend and 29% had a stable trend over the 26-year period. The increasing trend locations were positively correlated with site water balance [the Palmer Drought Severity Index (PDSI)], i.e., vegetation response increased during wet periods and decreased during drought. The increasing trend was positively and negatively (non-linearly) correlated with grazing in individual paddocks from 1980 to 1997.
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The North American landscape characterization Landsat Pathfinder Project363371)| false
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Retrospective Assessment of soil stability on a landscape subject to commercial grazingAfrican Journal of Range & Forage Science20127)| false
Washington-Allen, R.A., N.E. West and R. D. Ramsey. 2003b. Remote sensing-based dynamical systems analysis of sagebrush steppe vegetation in rangelands. African Journal of Range & Forage Science 20:100.
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Remote sensing-based dynamical systems analysis of sagebrush steppe vegetation in rangelandsAfrican Journal of Range & Forage Science20100)| false
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Change and Time Series Analysis. Explorations in Geographic Information Systems Technology1)| false
Madhur Anand, CAN (forest ecology, computational ecology, and ecological complexity)
S. Bagella, ITA (temporal dynamics, including succession, community level patterns of species richness and diversity, experimental studies of plant, animal and microbial communities, plant communities of the Mediterranean)
P. Batáry, HUN (landscape ecology, agroecology, ecosystem services)
P. A. V. Borges, PRT (community level patterns of species richness and diversity, sampling in theory and practice)
A. Davis, GER (supervised learning, multitrophic interactions, food webs, multivariate analysis, ecological statistics, experimental design, fractals, parasitoids, species diversity, community assembly, ticks, biodiversity, climate change, biological networks, cranes, olfactometry, evolution)
Z. Elek, HUN (insect ecology, invertebrate conservation, population dynamics, especially of long-term field studies, insect sampling)
T. Kalapos, HUN (community level plant ecophysiology, grassland ecology, vegetation-soil relationship)
G. M. Kovács, HUN (microbial ecology, plant-fungus interactions, mycorrhizas)
W. C. Liu,TWN (community-based ecological theory and modelling issues, temporal dynamics, including succession, trophic interactions, competition, species response to the environment)
L. Mucina, AUS (vegetation survey, syntaxonomy, evolutionary community ecology, assembly rules, global vegetation patterns, mediterranean ecology)
P. Ódor, HUN (plant communities, bryophyte ecology, numerical methods)
F. Rigal, FRA (island biogeography, macroecology, functional diversity, arthropod ecology)
D. Rocchini, ITA (biodiversity, multiple scales, spatial scales, species distribution, spatial ecology, remote sensing, ecological informatics, computational ecology)
F. Samu, HUN (landscape ecology, biological control, generalist predators, spiders, arthropods, conservation biology, sampling methods)