Are biological corridors helping ecosystems to adapt to climate change in Costa Rica ?

(1)

Are biological corridors helping ecosystems to adapt

to climate change in Costa Rica?

Bruno Locatelli

1 , Pablo Imbach

2 and Yves Laumonier

1

CIRAD-CIFOR, Bogor, Indonesia

2

CATIE, Turrialba, Costa Rica

For further information, please contact b.locatelli@cgiar.org

Introduction

As the distribution of biomes relates mainly to temperature and precipitation, it will be affected by climate change. The future distribution depends on the ability of plants to

migrate, which may be reduced by landscape fragmentation. Biological corridors have been proposed for facilitating the adaptation of ecosystems to climate change. In Costa Rica,

as protected areas are increasingly isolated, biological corridors are being progressively implemented (Figure 1).

Objective

Assessing the contribution of biological corridors (BC) to the adaptation of protected areas (PA) to climate change in Costa Rica

Methods and data

Model overview: We developed a spatial model with cellular automata, a resolution of 2

arc min (~5 km) and time steps of 10 years (from 1990 to 2050). Species can move between pixels when climate evolves, depending on their capacities and the landscape (Figure 2).

Vegetation representation: We used the Holdridge bioclimatic classification of life zones

(Figure 3). Assumption: the vegetation adapted to each life zone is composed of 5 species with different migration capacities.

Data: We used altitude and climate data from WorldClim, land use, protected areas and

corridors from CCAD & World Bank.

Model runs:

Analysis: Index of climate change impact = status of vegetation in PA in 2050, compared

to two hypothetical scenarios (index = 0 for full natural vegetation in the country, i.e. unavoidable impact; index = 1 without migration, i.e. maximum impact).

Contributions of individual corridors: difference between the impacts of climate change on PA between a scenario with all BC and a scenario with all BC but one.

Results and discussion

The enhancement of BC reduces the impacts of climate change on PA (Figure 4)

Analysis of sensitivity: results differ significantly with different climate scenarios (p<0.05) but not with different migration representations.

The PA most potentially impacted by climate change are located in the mountains and the dry northwest part of the country (results not shown).

The PA benefiting the most from BC are located in the Northwest, where PA are potentially highly impacted and poorly connected (Figure 5).

Corridors are benefiting less to PA in the southeast central mountains, because the PA are already connected.

Conclusion

Corridors play an important role in facilitating the adaptation of protected areas in Costa Rica, especially altitudinal corridors and dry area corridors. This role is clear, even when

uncertainties on climate and migration are taken into account. Climatic uncertainties have more influence on the results than uncertainties on migration processes. Several climate

scenarios should therefore be considered when planning corridors for adaptation to climate change.

Figure 4. Impact of climate change on PA

with different policies (bars represent the standard deviation of the results of the 16 runs for each policy option)

Figure 5. Contribution of individual

corridors to the adaptation of protected areas

Figure 3.

Holdridge life zones

Figure 2. Algorithm

4 migration representations

4 climate scenarios X X 3 policy options = 48 runs

Species can migrate through contiguous or non

contiguous pixels

Two sets of values for migration capacities of the 5 species (100, 250, 500, 1000 & 2000 m/yr and 50,

100, 250, 500 & 1000 m/yr) HADCM3 and CCCMA climate models A2 and B2 greenhouse gas emission scenarios

- Enhanced corridors (natural vegetation in BC) - Status quo (current vegetation in BC)

- Degraded corridors (no vegetation in BC)

Estimate 1990 Life Zone (lz₁₉₉₀) Estimate Current Life Zone (lz_current)

Controller Pixel

px

Species

sp

Create baseline: presence(px,sp)=1 if sp is adapted to lz₁₉₉₀

Initialize

Run

Is sp adapted to lz_current? No: reduce presence

Yes: Is sp already present in px? Yes: increase presence

(with upper bound: carrying capacity) No: Is sp present in neighbourhood? (radius= migrationCapacity (sp))

Yes: introduce species No: nothing Update indicators Ne xt d ec ad e

Enhanced corridors Status quo Degraded corridors

0 0.05 0.1 0.15 0.2 0.25 CC Im pa ct In de x

Figure 1. Corridors and

protected areas in Costa Rica

thorn steppe / woodland desert scrub dry forest moist

forest forestwet forestrain desert

scrub thorn

woodland very dryforest forestdry moistforest forestwet forestrain desert

desert

steppe moist

forest forestwet forestrain desert

scrub desert

dry

scrub forestmoist forestwet forestrain desert

dry

tundra tundramoist tundrawet tundrarain desert desert desert

annual precipitation (mm) 62.5 125 250 500 1000 2000 4000 8000 1600 0 0.125 0.25 0.5 1 2 4 8 16 32

potential evapotranspiration rati o humidity provinces super-humid per-humid humid sub-humid semi-arid arid perarid super-arid polar subpolar boreal warm temperate subtropical tropical cool temperate 1.5 °C 3 °C 6 °C 24 °C 12 °C latitudinal regions biotemperatur e critical temperature line alvar alpine subalpine lower montane premontane montane altitudinal belts