39 research outputs found
Spatial heterogeneity and irreversible vegetation change in semi-arid grazing systems
Recent theoretical studies have shown that spatial redistribution of surface water may explain the occurrence of patterns of alternating vegetated and degraded patches in semiarid grasslands. These results implied, however, that spatial redistribution processes cannot explain the collapse of production on coarser scales observed in these systems. We present a spatially explicit vegetation model to investigate possible mechanisms explaining irreversible vegetation collapse on coarse spatial scales. The model results indicate that the dynamics of vegetation on coarse scales are determined by the interaction of two spatial feedback processes. Loss of plant cover in a certain area results in increased availability of water in remaining vegetated patches through run-on of surface water, promoting within-patch plant production. Hence, spatial redistribution of surface water creates negative feedback between reduced plant cover and increased plant growth in remaining vegetation. Reduced plant cover, however, results in focusing of herbivore grazing in the remaining vegetation. Hence, redistribution of herbivores creates positive feedback between reduced plant cover and increased losses due to grazing in remaining vegetated patches, leading to collapse of the entire vegetation. This may explain irreversible vegetation shifts in semiarid grasslands on coarse spatial scales
Excavation of an early 17th-century glassmaking site at Glasshouse, Shinrone, Co. Offaly, Ireland
An archaeological research excavation was conducted in the area immediately surrounding an upstanding glassmaking furnace near Shinrone, Co. Offaly, Ireland. It dates to the early to mid 17th century and was built and operated by French Huguenots, probably de Hennezells (de Hennezel/Henzeys/Hensie) who had settled in this region as part of the Crown plantation of King’s County (now Co. Offaly). This furnace, which employed wood rather than coal as a fuel, is a very rare survival, with no other upstanding examples known in Ireland, Britain or the Lorraine region of France where the form probably originated
Mouse Chromosome 11
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46996/1/335_2004_Article_BF00648429.pd
Angioplasty balloon occlusion of internal thoracic artery in redo surgery in patients with coronary artery bypass operations
Polymorphism for PCR-analyzed microsatellites between the inbred mouse strains LG and SM
Resolution of the staggerer (sg) mutation from the neural cell adhesion molecule locus (Ncam) on mouse Chromosome 9
Spatial heterogeneity and irreversible vegetation change in semi-arid grazing systems
Recent theoretical studies have shown that spatial redistribution
of surface water may explain the occurrence of patterns
of alternating vegetated and degraded patches in semiarid grasslands.
These results implied, however, that spatial redistribution processes
cannot explain the collapse of production on coarser scales observed
in these systems. We present a spatially explicit vegetation model to
investigate possible mechanisms explaining irreversible vegetation
collapse on coarse spatial scales. The model results indicate that the
dynamics of vegetation on coarse scales are determined by the interaction
of two spatial feedback processes. Loss of plant cover in a
certain area results in increased availability of water in remaining
vegetated patches through run-on of surface water, promoting
within-patch plant production. Hence, spatial redistribution of surface
water creates negative feedback between reduced plant cover and
increased plant growth in remaining vegetation. Reduced plant cover,
however, results in focusing of herbivore grazing in the remaining
vegetation. Hence, redistribution of herbivores creates positive feedback
between reduced plant cover and increased losses due to grazing
in remaining vegetated patches, leading to collapse of the entire
vegetation. This may explain irreversible vegetation shifts in semiarid
grasslands on coarse spatial scales