A few more thoughts regarding predator prey / resource consumer dynamics and population regulation: Food webs From: Bolen and Robinson (2003)

A few more thoughts regarding predator prey / resource consumer dynamics and population regulation: Top-down vs Bottom-up regulation From: Bolen and Robinson (2003)

A few more thoughts regarding predator prey / resource consumer dynamics and population regulation: Trophic cascade:Loss of key species in a community sparks indirect effects and subsequent changes to biological communities. Classic example: Kelp, Sea Otters, Sea Urchin

In this setting the sea otter is considered a keystone species

From Groom et al, 2006

Factors affecting population size and persistence: a quick review Species life history characteristics Density-dependent factors Density-independent factors Intraspecific and Interspecific relationships AND… interconnectedness/interaction between populations

Interactions and interconnectedness of populations Many species exist in more than 1 population Metapopulation = population of populations –set of semi-isolated subpopulations, between which movement is possible –linked by immigration and emigration –subpopulations disappear (extinction) and others appear (colonization) through time

Metapopulation Mountain Sheep in Southern CA (Bleich et al. 1990) Range of Total Population (within fenced highways) Subpopulations Area temporarily unoccupied Interpatch movement

What is Habitat?

Scale?

Urban sprawl in eastern King County, Washington, USA (1974  1998) Habitat loss, fragmentation and alteration

edge interior Habitat Loss & Fragmentation Overall loss of habitat (% cover) Isolates remaining habitat Increases edge habitat

Major causes overgrazing deforestation agriculture fuelwood urbanization industry pollution/contaminants

Stages of fragmentation stage 1: dissection

Stages of fragmentation stage 1: dissection stage 2: perforation

Stages of fragmentation stage 1: dissection stage 2: perforation stage 3: fragmentation

Stages of fragmentation stage 1: dissection stage 2: perforation stage 3: fragmentation stage 4: attrition **consider biological processes operating at different stages**

Stages of fragmentation stage 1: dissection stage 2: perforation stage 3: fragmentation stage 4: attrition Matrix Habitat for species ‘x’

Population and community-level consequences of fragmentation interrupts ecological patterns and processes –e.g. species interactions, behavior, dispersal, etc.

Population and community-level consequences of fragmentation interrupts ecological patterns and processes reduced habitat patch area –leads to small populations and/or disappearance of populations

Population and community-level consequences of fragmentation interrupts ecological patterns and processes reduced habitat patch area edge effect –impacts of non-habitat extend into habitat patch –effective patch size is smaller

Edge Effects Increased nest parasitism Brown-headed Cowbird Increased nest predation –Predators edge-affiliated: jays, ravens Barriers to movement Alter microclimate: drier and warmer Positive for some species, negative for other species Steller’s Jay Brown-headed Cowbird

Population and community-level consequences of fragmentation interrupts ecological patterns and processes reduced habitat patch area edge effect –impacts of non-habitat extend into habitat patch –effective patch size is smaller

size and edge effects –role of edge area vs. shape

Brood parasite

An eastern phoebe nest with a parasitic brown-headed cowbird chick. Courtesy of Jeffrey Hoover.

Songbird disappearance Eastern U.S. Artificial nests Predation rates 70% in suburbs, 2% in Smokies

Population and community-level consequences of fragmentation interrupts ecological patterns and processes reduced habitat patch area edge effect increased patch isolation –decreased successful movement (immigration and emigration) –increased likelihood of local extinction

Processes operating between fragments dispersal –increasing fragmentation decreasing colonization rates –leads to decreasing # of species within patch –increasing risk of local extinction of species within patch

Processes operating between fragments dispersal matrix –disturbed/converted habitat surrounding fragments –potential roles? matrix

Persistence of populations In which directions would you predict net movement of individuals? Which populations are more likely to persist? why? Disappear? What are the factors most important in determining a population’s likelihood to persist? Which populations, if they disappear, are most likely to be recolonized?

Grizzly bear 50,000 historic estimate Persecution and habitat changes == about 1,200 wild grizzlies remain in lower 48

Grizzly bear ecosystems <20 0? > ?

Y2Y Yukon to Yellowstone Conservation Initiative Goal: maintain and sustain region to allow wilderness, wildlife, native plants, and natural processes to function as an interconnected web of life Partnerships of NGOs, businesses, foundations, concerned citizens, scientists Based on science Balance area needs

Cascade Land Conservancy In conjunction with members of communities, work toward large- scale conservation Habitat Lands Farmland Working Forests Parks, Trails and Open Spaces Shorelines and Estuaries