PARENT SESSION
Oral Session 8: Forest Ecology I: Dynamics and Succession.
Presiding: A Fiala and D Kashian
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room B 117.

Environmental causes and consequences of disturbance: Topography, forest soils and agricultural land use in central New York.

Flinn, Kathryn^*,1, Vellend, Mark¹, Marks, P.¹, ¹ Cornell University, Ithaca, NY

ABSTRACT- Broad-scale patterns in plant distribution and abundance largely reflect variation in climate, topography and soils, but disturbance complicates relationships between environment and vegetation. Environmental and disturbance-related influences on plant distributions also interact; disturbances affect certain communities more than others, and they may cause persistent environmental changes that affect recovering vegetation. Across diverse landscapes, forest clearance for agriculture and subsequent field abandonment are dominant forms of disturbance shaping natural communities. Plant species richness and composition of mature forests on abandoned agricultural lands consistently differ from forests that were never cleared. To understand the processes creating this pattern, we asked whether environmental conditions differ among forests of different history, and whether initial decisions or land use itself created these differences. For one county in central New York, we related geographical patterns of forest clearance and field abandonment to variation in topography and soils using GIS. We evaluated the consequences of these decisions for the distribution of current forests, and we assessed the effects of agricultural land use on the chemical properties of forest soils with field-collected soil samples from adjacent postagricultural and uncleared forests. Steeper slopes, less accessible lands and lower-lime soils tended to remain forested, and farmers tended to abandon fields that were steeper, farther from roads, lower in lime and more poorly drained. Factors affecting land-use decisions also depended on location within the county. Soil properties of postagricultural and uncleared forests largely overlapped. Forests on lands abandoned from agriculture 80-100 years before had slightly higher pH and nutrient availability than adjacent, uncleared forests, but these changes were small compared to environmental variation across the county. Despite differential use of lands and direct effects of land use, many current forests share similar topography and soils, so that subtle environmental differences among forests of different history may affect plant distributions only at fine scales.

Key words: land use, GIS, forest history, soil