Ronald M. Welch (PI)

Vani Starry Manoharan

University of Alabama in Huntsville

Environmental Stability of Forest Environmental Stability of Forest Corridors in the Corridors in the

Mesoamerican Biological Corridor (MBC) Mesoamerican Biological Corridor (MBC) RegionRegion

ContributorsContributorsUniversity of Alabama in HuntsvilleUniversity of Alabama in Huntsville

– Central American Land Use Changes and ClimateCentral American Land Use Changes and Climate» Ronald Welch, PIRonald Welch, PI» Vani Starry Manoharan Vani Starry Manoharan » Robert LawtonRobert Lawton» Tom SeverTom Sever» Daniel IrwinDaniel Irwin

- - Modeling land use change and climate using GEMRAMSModeling land use change and climate using GEMRAMS» Aaron Song Aaron Song » Udayasankar NairUdayasankar Nair

– Precipitation Processes over forested and deforested Precipitation Processes over forested and deforested regionsregions

» John Mecikalski John Mecikalski » Matt WingoMatt Wingo

Proposed Mesoamerican Biological Proposed Mesoamerican Biological CorridorCorridor

Primary Objective

• Determine the extent of which land use change disturbances have affected and are affecting regional and local climatic conditions…

• in ways that influence the environmental stability of protected regions and proposed corridors in the Mesoamerican Biological Corridor

Land use change disturbancesLand use change disturbances

Land use change impacts the local climate primarily by changing the surface energy budget.

1.Vegetation type2.Surface roughness 3.Soil type4.Soil moisture5.Albedo6.Land surface

temperature

Surface Energy Budget

1. Petén Basin – Guatemala1. Petén Basin – Guatemala

• Characterized by low relief (<300m)

• 30x30 km2 samples of forested deforested and partially forested region were picked

Manoharan et al., 2009

Data and methodologyData and methodologyMODIS Level 1B calibrated radiance data for March to

September, 2000 and 2008 are used to derive Normalized Difference Vegetation Indices (NDVI), surface temperatures and soil moisture values.

March - April peak of dry season [Ray et al., 2006] May - July dry to wet season August - September peak of the wet season.

MODIS channels 1 (0.645m – visible red) and 2 (0.858m – near infra red) are used to derive NDVI values, and channel 31 (11.3m) is used for the land surface temperature retrievals.

A supervised maximum likelihood classification was performed to estimate the rate of deforestation.

Pixels are broadly classified into two classes as forested and deforested regions, and these classes are well-separated with an accuracy of 94%.

ResultsResultsPartially

Deforested10 11 12

2000 17.7% 12.9% 13.4%

2008 2.9% 8.3% 4.7%

2.64% of the overall region has been deforested from 2000 to 2008

2. GEMRAMS2. GEMRAMSImpacts of deforestation on the proposed Impacts of deforestation on the proposed

corridors in northern Guatemala corridors in northern Guatemala [[Welch et al.,Welch et al., 2010 (submitted)] 2010 (submitted)]

• GEMRAMS: Regional Atmospheric Modeling System (RAMS) coupled with General Energy and Mass Transport Model (GEMTM) (Beltrán et al., 2005)

• GEMRAMS simulates dynamic interactions between the atmosphere and growing canopy

• Use GEMRAMS to simulate the vegetation in the Petén areas for half forested and half deforested for half forested and half deforested scenario (dry and wet day during March 2003).scenario (dry and wet day during March 2003).

March 8March 8thth, 2003 – 12 noon LT, 2003 – 12 noon LT

Forests

Pastures

Forests

Pastures Pastures

Forests

Temp 2m

Latent heat flux (W/m2)Sensible heat flux (W/m2)

Topography

Circulation pattern along ABCirculation pattern along AB (March 23(March 23rdrd))

Pasture Forest

Pasture

PasturePasture

Pasture

Forest

Forest Forest

Forest

ResultsResults

Dry day• LHforest and LHpasture very low

(30W/m2) • SH ~ 3 to 10 times LH• PBL ~ 2000m(afternoon)• Cloud cover ~ 13%• No precipitation

Convective Day• Convection started early over

the pastures• By mid-day convection was

over forest and pasture• Later noon convection

decreases over F and P, but much faster over F

• LH very large ~ 700 W/m2

• Cloud cover higher over P• Precippasture (~60mm)>Precipforest

(~25mm)

• PBLpasture < PBLforest

ResultsResults

• In terms of the sustainability of the lowland corridors, forested corridors will experience warmer conditions due to higher temperatures in surrounding deforested areas.

• Precipitation: The forested corridors will receive higher than normal precipitation rates due to the fact that surrounding deforested regions generate higher convective activity.

• The above scenario implies a “climate tipping point” will not occur in the proposed corridor regions which would threaten their stability and sustainability.

Cloud top cooling rate (GOES – E)Cloud top cooling rate (GOES – E)

There were no significant differences in cloud top height in the forested and deforested regions in either the dry or wet seasons, but deep convection is

more prevalent in the dry season.

ConclusionConclusion

• Deforestation is a continuing process

• Partially deforested regions in Guatemala 9.3% decrease in forests from 2000-2008

• Forested regions have a relatively stable environment

• Forested corridors in low lands are not threatened by the surrounding deforestation

Next Step

• Look at the corridors in high altitude regions