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Shen et al. 2008 Proposed conservation landscape for Giant Pandas in the Mishan Mtns. China Cons Biol 22:1144-53 . Core Habitat CH 1,3,5,6,8 25% chance of extinction in 100yrs Recommend CORRIDORS PL1 -4. OUTLINE Corridors as a conservation tool benefits costs recent evidence

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slide1

Shen et al. 2008

Proposed conservation landscape for Giant Pandas in the Mishan Mtns. China

Cons Biol 22:1144-53

Core Habitat

CH 1,3,5,6,8

25% chance of extinction in 100yrs

Recommend

CORRIDORS

PL1 -4

slide2

OUTLINE

Corridors as a conservation tool

benefits

costs

recent evidence

large scale examples

slide3

MOVEMENT CORRIDORS: CONSERVATION BARGAINS OR POOR INVESTMENTS?

Simberloff et al 1992 Conservation Biology 493-504

slide4

“a wildlife corridor is a linear landscape element which serves as a linkage between historically connected habitat, and is meant to facilitate movement between these natural areas”

McEuan 1993

slide5

Benefits of corridors

1962- species-area relations

Corridors increase area

linking reserves should increase species richness

1974 - equilibrium theory of island biogeography

Corridors increase immigration

Equilibrium number of species should increase

Corridors may aid dispersal,

allow recolonization or rescue of populations,

increase genetic diversity, prevent inbreeding

reduce stochastic effects

---> general recommendation for reserve design

slide6

Benefits of corridors

Beier 1993,1995 - cougars in southern California

150km2

Hwy

75km2

Santa Ana mountains 2070 km2 - 20 adults

slide7

Beier 1993, 1995

Radiocollared cougars

Movement paths

use riparian corridors

Mortality

around housing developments

roads

Models found

- cougars will not persist in the small patches

- population in large patch will not persist without immigration from Palomar Range

Concluded A CORRIDOR IS ESSENTIAL

slide8

Benefits of corridors

Maintain pathways for migratory species

Eg quetzals in Costa Rica

Protected breeding habitat

Monteverde Reserve

Proposed corridors

Low elevation habitat used during non-breeding season

slide9

Benefits of corridors

Maintain connectivity for ecological processeses

Eg pollination by bees (Rudbeckia) and butterflies (Lantana)

SOURCE

Source pollen dusted with dayglo powder

Townsend and Levey 2005 Ecol 86: 466-75

slide10

Benefits of corridors

1 Aid dispersal

2. Allows migration

Maintains ecological processes

4. Allows range shifts due to climate change

5. Provision of escape routes from fire

6. Opportunity to avoid predation

slide11

Simberloff (1992): much cited paper

MOVEMENT CORRIDORS:

CONSERVATION BARGAINS OR POOR INVESTMENTS?

Data on corridor use is limited/

experiments are not rigorous

Data on consequences of corridors for demography and genetic structure is sparse

Costs of corridors may be better spent on making larger reserves -

slide12

Hazards of corridors

  • Corridors may provide avenue for catastrophes (predators, fire, disease)

corridors may attract edge-inhabiting predators

isolated reserves quarantine disease

  • Corridors may act as entry route for exotics

corridors may favour movement of introduced spp

corridors may be reservoir for weeds

  • Corridors may function as sinks
  • Corridors with no buffer zone may expose migrants to danger

Exposure to domestic animals, roads, etc

5. Corridors may facilitate poaching/trapping

slide13

Corridors: a philosophical slant

Corridors are easily understood.

Is it good conservation practise to sell the easiest program in the absence of evidence it is the most effective?

Is it beneficial for people to feel that they are doing something important for conservation in the absence of evidence they are doing anything

slide14

17 years after Simberloff

Do corridors provide connectivity?

Approaches

do animals/plants use corridors

do corridors influence demography

do corridors influence genetic structure

do corridors influence diversity

slide15

do animals/plants use corridors?

Experimental corridors in S Carolina

Corridors promote movement in diverse taxa

slide16

do animals/plants use corridors?

Experimental corridors in S Carolina

Obs

Birds usually fly parallel to edge

Model

Predict bird and seed movement in connected/unconnected patches

Expt

Feed birds-track seeds of wax myrtle

slide17

do corridors influence demography?

Control corridor fragment

5700 individuals

22600 captures

Survival higher in corridor linked grids

Population sizeless variable in corridor linked grids

Coffman et al 2001 Oikos 93: 3-21

slide18

do corridors influence demography?

Mountain pygmy possum

Contiguous Fragmented by ski development

Males can’t move

--> lower female survival

and skewed sex ratio

+ TUNNEL

normal sex ratio and survival

Females winter at higher elevation

Males move to lower elevations

slide19

do corridors influence genetic structure?

  • Red squirrels
  • Deforestation in 19th century -->
    • Dwindling poplations in small isolated patches
    • Populations become genetically distinct
  • Reforestation 1950’s --->
  • Kielder forest
  • links some populations
  • Genetic data - 1920’s museum skins
  • - 2001 resampled populations
slide20

do corridors influence genetic structure?

Red squirrels

Fragmented Linked by stepping stone corridor

Reforestation has allowed genetic mixing of Scottish and Cumbrian populations

slide21

do corridors influence species diversity?

Gilbert et al. 1998 ProcRSoc 265: 577-82

Moss micro-arthropod communities on rocks

What is predicted?

slide22

do corridors influence species diversity?

Gilbert et al. 1998 ProcRSoc 265: 577-82

Moss micro-arthropod communities on rocks

What is predicted?

slide23

Corridors and connectivity

Diverse taxa do use corridors

- reasonable evidence

Corridors can influence demography

- some evidence

Corridors can influence genetic processes

- some evidence

Corridors can influence diversity

- some evidence

Despite criticisms

Corridors may be best solution to a complex problem

slide24

Conservation corridors

Example 1. The Terai Arc

250 bengal tigers

11 protected areas

slide25

Conservation corridors

Example 1. The Terai Arc

250 bengal tigers

WWF+ partners

Goal - link the 11 protected areas

Khata corridor - 3 km long

Links Royal Bardia to Kataniaghat

2001 - restoration commenced

community forests and plantations

2004 - Elephant and tiger using corridor

slide26

Conservation corridors

Example 2. The Mesoamerican corridor

Wildlife Conservation Society initiative

7 countries

Chiapas, Mexico to

Darrien Gap, Panama

1996 GIS model linking reserves, remaining forest

Progress slow

Costa Rica 39

Mexico/Belize 4

slide27

Corridors- unresolved questions

Which spp use corridors? Which benefit

How do residency and movement rates differ among taxa

“passage” vs “corridor dwellers”

How does utilization change with shape, width, length, landscape?

Will corridors promote the movement of exotics and disease?

slide28

Gibert ert al. 1998 Corridors maintain species richness in the fragmented landscapes of a microecosystem. P Roy Soc Lond B 265: 577-582

Damschen, EI et al. 2006 Corridors increase plant species richness at large scales

SCIENCE 313: 1284-6

Shepherd, B and Whittington, J 2006. Response of wolves to corridor restoration and human use management ECOLOGY AND SOCIETY 11

Dixon, JD et al. 2006. Effectiveness of a regional corridor in connecting two Florida black bear populations CONSERVATION BIOLOGY 20: 155-162

Martensen et al. 2008. Relative effects of fragment size and connectivity on bird community ib the Atlantic Rainforest BIOLOGICAL CONSERVATION 141: 2184-92

Lees AC and Peres CA 2008 Conservation value of remnant riparian corridors of varying quality for Amazonian birds and mammals Conservation Biology 22 439-449

Beier P et al. 2008 Forks in the road: choices in procedures for designing wildland linkages. CONSERVATION BIOLOGY 22: 836-51

slide29

Points for discussion

Corridors - are benefits taxon specific

- how can we examine costs

- what do we want them to do

- how do we design them