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Reserve design features for persistence SIZE Edge to area ratio Shape Environmental gradients Disturbance regime Corridors Matrix habitat CONNECTIVITY Functional units SIZE Larger size • More species (interactions, functions), S-A relationship • More habitats (interactions, functions) • Larger populations – • Protects vulnerable species – Area demanding: large-bodied, high-trophic level, rare – Habitat specialists (if habitat included) – Species requiring multiple habitat types • Shape Reduced edge/area ratio, edge effects • Disturbance regime: maintenance of disturbancegenerated patch heterogeneity • Includes whole functional units • Includes whole environmental gradients Ecosystem Boundaries? • It is easy to picture ecosystems as having distinct boundaries. • The area of transition from one ecosystem to another is considered to be an ecotone. • Ecotones have a mixture of species from both ecosystems. – A marsh between a freshwater lake and dry land. – Zone of grasses, shrubs, and scattered small trees between forests and grasslands. Where does one ecosystem end and the other begin? Two examples of ecotones. Species Overlap in Ecotones Land zone Transition zone Number of species Species in land zone Species in aquatic zone Species in transition zone only Aquatic zone Edge Effect • Higher species diversity found on the edge of an ecosystem (ecotone) than in the interior – Marsh and open water (shrimp, crabs, juvenile finfish) • Edge species – those species that are concentrated in ecotones • Sharp edge usually a poor habitat – Clear cut – forest edge SIZE & EDGE EFFECTS Edges create core versus edge habitat Example: many songbirds experience high nest predation near edges in woodlots within sub-urban areas From Prim Shape and edge effects Meffe & Carroll 1997 Biological Consequences of Fragmentation • Edge Effects • One of the best documented effects of fragmentation are ‘edge effects’ • Edge effects have mostly been examined in forests • Sunlight and wind alter the micro-climate at the forest edge, changing which plant species are favored The forested areas of Warwickshire, England Habitat fragmentation • Above and beyond habitat loss • Isolation: reduced immigration, recolonization • Edge effects From Primack 2002 Biological Consequences of Fragmentation • In WI forests, edge zones of shadeintolerant plants may extend 10-15m into a forest (N,E,S) and 30m (W) • In Douglas Fir forests of Pacific NW, increased rates of blowdowns and other physical edge effects may extend over 200m into the forest • In Queensland, elevated rates of canopy and sub-canopy damage extend 500m in Biological Consequences of Fragmentation • In some landscapes, especially in warmer climates, sealing of edges occurs through accelerated growth and increased regeneration of understory trees and shrubs • In some cases animals are then attracted to these edges, which may then function as an ‘ecological trap’ • In MI, songbirds nest at higher rates Biological Consequences of Fragmentation • Consider the impact on birds • Roads and powerline corridors as narrow as 8m may produce edge effects • Cowbird parasitism may be significant for 100’s of m into a forest • Predation can also be significantly higher near the edges as densities and movements of raccoons, opossums, crows, foxes, jays, skunks, are all higher DISTURBANCE REGIME • Disturbance promotes habitat heterogeneity – By resetting successional sequence in parts of the landscape – Creating patchiness in the landscape which is determined by the temporal and spatial scale of the disturbance(s) • SIZE & DISTURBANCE REGIME Disturbance promotes habitat heterogeneity – mosaic of patches at different successional stages • Habitat heterogeneity: – supports species requiring multiple habitat types – Supports early successional species (e.g. Heath fritillary butterfly = “Woodman’s follower”) • Size of reserve ideally as big as or bigger than scale of likely disturbances Invasion HOMOGENIZATION – The distribution of species on Earth is becoming more homogenous – The rate of invasion is increasing over time Growth in Number of Marine Species Introductions in North America and Europe SIZE & FUNCTIONAL UNITS Functionally interdependent ecosystems: e.g. “a complex, dynamic patchwork of mangroves, sea grass bed and reefs” (Moberg & Ronnback 2003) Reserve design features for persistence SIZE: Bigger is better! Edge to area ratio Shape Environmental gradients Disturbance regime Corridors Matrix habitat CONNECTIVITY Functional units CONNECTIVITY • Isolation is a key factor causing loss of species from reserves – Preventing gene flow, maintenance of genetic diversity – Reducing recolonization following extinction (rescue effect) – Preventing access between summer/winter grounds for migratory species – Preventing access to multiple habitat types needed for different life stages – Preventing response to global warming CONNECTIVITY:Multiscale responses PROBLEM of FRAGMENTATION RESPONSE – Preventing gene flow, maintenance of genetic diversity – Reducing recolonization following extinction (rescue effect) •Create corridors between reserves •Manage the matrix around reserves – Preventing access between summer/winter grounds for migratory species – Preventing access to multiple habitat types needed for different life stages – Preventing response to global warming Wildlife overpass Transportation Equity Act for the 21st Century provides funding Managing the Matrix Making matrix “friendly” to wildlife --- Reserve zonation: core, buffer, transition Wildlife friendly farming/Restoration CONNECTIVITY: Multiscale responses PROBLEM of FRAGMENTATION RESPONSE – Preventing gene flow, maintenance of genetic diversity – Reducing recolonization following extinction (rescue effect) •Create corridors between reserves •Manage the matrix around reserves – Preventing access between summer/winter grounds for migratory species Protect migratory routes/stop-overs – Preventing access to multiple habitat types needed for different life stages – Preventing response to global warming Stop-over sites along songbird migration routes • Neotropical birds • Use radar to detect nocturnal bird movement – Timed to get departure events from stopover points (20-40 min after sunset) – Signal characteristics http://www.njaudubon.org/Education/Oases/RadImages.html Breeding wintering CONNECTIVITY: Multi-scale responses PROBLEM of FRAGMENTATION RESPONSE – Preventing gene flow, maintenance of genetic diversity – Reducing recolonization following extinction (rescue effect) •Create corridors between reserves •Manage the matrix around reserves – Preventing access between summer/winter grounds for migratory species Protect migratory routes/stop-overs – Preventing access to multiple habitat types needed for different life stages •Include whole functional units, disturbance regimes, environmental gradients within reserves or reserve networks – Preventing response to global warming •Include elevational or latitudinal gradients within reserves New Reserve Design Methods • Represent species or habitats efficiently • Minimize edge effects, maximize clustering • Maximize connectivity Leslie et al. 2003 Ecol App. Conclusions • Biodiversity has great value, both intrinsically, and also because human life depends on it • But, it is under threat, from habitat loss and degradation, invasive species, climate change, pollution and over-exploitation • Conservation biologists have many tools to protect biological diversity, from genetic to ecosystem levels. Conclusions • Protected areas are an important tool for biodiversity conservation. • The design of protected areas and reserve networks should foster representation of biodiversity and its persistence. – Reserves need to be sited efficiently to represent biodiversity. – Size, shape and connectivity of reserves and relationship with the surrounding landscape matrix are essential considerations for biodiversity persistence. Species Overlap in Ecotones Land zone Transition zone Number of species Species in land zone Species in aquatic zone Species in transition zone only Aquatic zone Ecosystem Function • A combination of production, respiration, and decomposition • What are the anthropogenic impacts on ecosystem function? • Ecological Footprint – a measure of the anthropogenic effect on the environment Ecological Footprint • • Ecological footprint – amount of land needed to produce the resources needed by the average person in a country Methods: 1. Correct consumption data for trade imports and exports Consumptionwheat= production + imports – exports 2. Convert to land area needed to produce the item Awheat = Cwheat / ywheat A=total area needed, C=consumed, Y=yield 3. Obtain per capita ecological footprint by dividing by population size fwheat = awheat/population size Ecological footprint in relation to available ecological capacity. It would take about 3 times the current land area of Earth if all 6.1 billion people consumed the same as the 276 million people in the US Per Captia Ecological Footprint (Hectares of land per person) Country 10.9 United States 5.9 The Netherlands India Country 1.0 Total Ecological Footprint (Hectares) 3 billion hectares United States The Netherlands India 94 million hectares 1 billion hectares
