PARENT SESSION
Oral Session #100: Landscape Ecology.
Presiding: T. Crist
Friday, August 9. 9:00 AM to 12:00 PM. Gila Meeting Room, TCC.
Landscape structure effects on nutrient pools of recovering milpas in Belize, C.A.
Franklin, Scott*,1, Kupfer, John2, 1 Department of Biology, Memphis, TN2 Department of Geography and Regional Development, Tucson, AZ
ABSTRACT- While studies of tropical deforestation and forest fragmentation often focus on ecological changes in forest remnants, the altered spatial arrangement of ecosystems across the landscape may also influence processes in the newly-created agricultural matrix. Given the forested matrix which has long dominated tropical areas is being replaced by an agricultural matrix, we believe that it is important to clarify how such changes affect community structure and function. In an effort to document landscape structure effects on community recovery, we examined small-scale agriculture fields (milpas) of different chronological age (STATUS = 1-2 years in-use, 1-2 years fallow, and 3-10 years fallow) and distance from older forest (DISTANCE <100 m or >150 m) near Indian Church, Belize. Previous data found significant differences in vegetation composition and structure between near and far milpas. In this presentation, we focus on soil nutrient pools as indicators of milpa recovery, specifically ammonium (Amm), phosphorus (P), calcium (Ca), potassium (K), and cation exchange capacity (CEC). P, Mg, and K had a significant STATUS effect (decreasing throughout the chronosequence) but no significant DISTANCE effect. Amm, however, had a weak STATUS*DISTANCE effect. Amm was highest in near milpas, but increased more dramatically during the chronosequence recovery in far milpas. Lower Amm in far milpas matched results of a vegetation survey that showed legumes were more dominant in far milpas, suggesting a nitrogen-limited recovery following agriculture exacerbated by landscape fragmentation.
KEY WORDS: soil nutrients, vegetation succession, Central America, disturbance