habitat fragmentation and loss
DESCRIPTION
Habitat Fragmentation and Loss. Habitat fragmentation = the breaking apart of continuous habitat 1. reduction in the total amount of original habitat (i.e. habitat loss) 2. subdivision of the remaining habitat into fragments, remnants, or patches (i.e. habitat fragmentation) - PowerPoint PPT PresentationTRANSCRIPT
Habitat Fragmentation and Degradation
Habitat Fragmentation and Loss
Habitat fragmentation = the breaking apart of continuous habitat1. reduction in the total amount of original habitat (i.e. habitat loss)2. subdivision of the remaining habitat into fragments, remnants, or patches (i.e. habitat fragmentation)3. introduction of new forms of area-use to replace lost habitat
Stages of Landscape Change1. Intact landscapes
2. Variegated landscapes
3. Fragmented
4. Relict landscapesMcIntyre and Hobbs (1999)
Species-Area RelationshipsRelationship between the size of a habitat (or island) and the number of species presentGenerally, for every 10x increase in habitat area you can expect a doubling in species abundance
Theory of Island BiogeographyPreston (1962) and MacArthur & Wilson (1963, 1967)Proposed that the number of species on an island is in a dynamic equilibrium between immigration and extinction
Island Biogeography: Area Effect
Island Biogeography: Distance Effect
Island Biogeography and ConservationAreas of application:How large should preserves be?How does isolation affect species number in reserves?What kinds of species will survive if area is reduced?Fragmentation and its Effects on Community StructureLoss of species richness
Changes in species interactions
Changes to trophic levels
Loss of foundation species
Edge EffectsHigh perimeter length to area ratioGreatest effects occur in small remnant areas and those with complex shapes
Deterministic and Stochastic ProcessesDeterministic = factors that are not necessarily a direct consequence of habitat fragmentation but arise from land uses typically associated with it.
Stochastic (chance) = natural factors related to demographics, genetic variation, environmental fluctuations, catastrophic events
Effects of IsolationImpairs regular movements of organisms
Impairs seasonal/migratory movements
Impairs dispersal movementsMetapopulationsLocal populations interconnected by movements of individuals between them
Salt Marsh Habitat Fragmentation, Degradation and Loss
Problems Facing Salt MarshesAgricultureChannelizationFlood control/LeveesRoadwaysDevelopment
Case Study: Louisiana
http://gallery.usgs.gov/search/Case Study: Louisiana
Seagrass Habitat Fragmentation, Degradation and Loss
Prop Scars!
Coral Reef Habitat Fragmentation, Degradation and Loss
Global annual value of reefs32
Mangrove Habitat Fragmentation, Degradation and Loss
Conservation in Fragmented SeascapesProtect and expand the amount of habitatEnhance the quality of the habitatManage across the entire seascapeIncrease connectivityPlan for the long-termLearn from current and previous efforts