Environmental Disturbance in the Greater Yucatan (EDGY) Project

1. Environmental Disturbance in the Greater Yucatan (EDGY) Project Southern Yucatan, Mexico Jennifer A. Holm, Dr. Deborah Lawrence, Dr. Laura Schneider, Dr. John Rogan, Birgit Schmook Funded and working in collaboration with: SYPR Project, NASA, NSF, UVa, Gordon and Betty Moore Foundation

2. Background - Rationale • Current: • Purpose: Study the effect of weather extremes in seasonally dry-tropical forests of the Southern Yucatan. • Level of study: ecosystem and landscape level responses to the increased frequency of large scale disturbances. • Looking at the damage effects of Hurricane Dean • Determining changes in forest structure, soil nutrients, fire frequency, spread of invasive species, and lastly changes in farmer’s agricultural practices and migration. • Many past projects and research: • 10+ yrs research in Southern Yucatan by research team • All focused on disturbances in the form of land cover/land use change/deforestation in the Southern Yucatan • Southern Yucatan Peninsular Region (SYPR) Project

3. Study Site – Southern Yucatan • Area: Southeastern coast of Quintana Roo to the southeastern portion of Campeche, Mexico. • 27,000 m^2 • Topography: Occupies both Caribbean coastal plains and uplands rising to 150m elevation. • Dry tropical forests • Multiple forest types • 2 biosphere reserves, many communally owned ejidos. • Xeric forests in the north and more wet, humid forests in the south region • Species Richness = 186 species • 3 hurricane impact zones (Category 5, 4, and 3) • 9000 m^2 each

4. Results - Overall • Past Overall Results from Disturbance Studies: • Deforestation resulting from land use change results: • Significant decline in available soil P over multiple cycles • Correlated with a decline in biomass recovery with each cycle • Smaller statured forests results in lower inputs of P from atmospheric dust • From less canopy trappings • Downward spiral and feedback • Lower input of new P feeds back to lower soil available P • Current EDGY Project: • Mapping of region into 3 damage levels via remote sensing/NDVI data (red, yellow, green). • Vegetation damage the same in impact zone 5 and 4. Damage to species did not change until reaching impact zone 3. • Potential correlation with change in environmental gradients • Red RS plots: No clear trend of damage to species between each impact zone (zone 5, 4, and 3). • Therefore red level damage consistent over whole study region. • Yellow and green RS plots: did show decrease in major damage to species in each impact zone. Lawrence et al. 2007, PNAS

5. SYPR Project • Southern Yucatan Peninsular Region Project – LCLUC • QUESTIONS: • What are the types, pace, and scale of land-use/cover change in the region, especially deforestation and agriculture? • What are the causes of these changes? Are they geographically explicit? • What are the implications of these changes on forest structure and function, the Calakmul Biosphere reserve, and regional carbon cycle. • APPROACHES: • Historical reconstructions, household surveys, econometric analysis, imagery classification and analysis, GIS data bases, forest ecology studies, nutrient cycling studies, hurricane impacts reconstruction • Using ecological, social (geography and economics), and GIS skills to understand sub-tropical land change and the human and environmental interactions. Full project description: http://earth.clarku.edu/lcluc/index.html B. L. Turner II (PI), J. Geoghegan (Co-PI), B. Savitsky (Co-PI)

6. Results – SYPR Project • Responding to 100 yrs of modern disturbance, SYPR forests continue to increase in biomass and tree height and size. • Biomass gained more by canopy height then basal area • Peak litter fall (forest productivity) occurs in old regrowth (12-25 yrs) forest – not mature forests. • Tree species composition same in old secondary and mature forests. • TM image analysis have identified = • 3 stages of forest regrowth, arrested growth, upland vs. bajo forest, cultivation, grassland vs. pasture. • Greatly enhanced through GPS’ed historical sketch maps • Major human disturbances are related to major Mexican policy changes. • Invasive species = • Inhibit forest regeneration, interrupt the crop-fallow cycle, reduce fallows on other lands, contribute to less standing biomass. • The amount of land disturbance could be assisting in precipitation declines. • Slash and Burn cycles are degrading soils • The selva mediana forest type is most effected by disturbance (decreasing in amount and structural changes). Full project description: http://earth.clarku.edu/lcluc/index.html

7. Final Thoughts • The Southern Yucatan has been and will continue to be an area subject to disturbance and land use change. • Relating and comparing results to dry tropical forests in other locations. • Human disturbance coupled with natural (hurricane) disturbance and a need to understand related ecosystem effects. • Forest productivity decreases with repeated deforestation. • Upland, moist forest most likely to be cut and anthropogenically disturbed. • Understanding land use history over whole region and relationship to natural disturbances. • 40% lower canopy level in secondary forest then in mature forest.

8. Next Steps • Current hurricane disturbance research: • Finish remote sensing validation and mapping • Finish damage data analysis on vegetation: • Various forest types, forest age, land use history, and soil fertility • Estimate damage disturbance level at large landscape level

9. Acknowledgments • Thank you! • Comments – Questions? • Acknowledgements: Rishiraj Das, Tana Wood, Karen Vandecar, Marcia DeLonge, Dana Richards, Marco Millones, Willy , Mirna Canul, NASA, NSF, Goore and Betty Moore Foundation, UVa, ECOSUR, Clark University, Rutgers University.