Environmental causes and consequences of forest clearance and agricultural abandonment in central New York, USA

Abstract

Aim Climate, topography and soils drive many patterns of plant distribution and abundance across landscapes, but current plant communities may also reflect a legacy of past disturbance such as agricultural land use. To assess the relative influences of environmental conditions and disturbance history on vegetation, it is important to understand how these forces interact. This study relates the geographical distribution of land uses to variation in topography and soils; evaluates the consequences of land-use decisions for current forests; and examines the effects of agricultural land use on the chemical properties of forest soils.Location Tompkins County occupies 1250 km 2 in central New York's Finger Lakes region. Like much of eastern North America, this area underwent forest clearance for agriculture during the 1800s and widespread field abandonment and forest recovery during the 1900s. The current landscape consists of a patchwork of forests that were never cleared, forests that developed on old fields and active agricultural lands.Methods We investigated relationships among topography, soils and land-use decisions by gathering information about land-use history, slope, aspect, elevation, soil lime content, soil drainage and accessibility in a geographic information system (GIS). To assess the effects of agriculture on forest soil chemistry, we measured pH, organic matter content and extractable nutrient concentrations in field-collected soil samples from 47 post-agricultural and uncleared forests.Results Steeper slopes, less accessible lands and lower-lime soils tended to remain forested, and farmers were more likely to abandon fields that were steeper, farther from roads, lower in lime and more poorly drained. Slope had by far the greatest impact on patterns of clearance and abandonment, and accessibility had a surprisingly strong influence on the distribution of land uses. The effects of other factors varied more, depending for example on location within the county. Current forest types differed accordingly in topography and soil attributes, particularly slope, but they also showed much overlap. Post-agricultural and uncleared forest soils had similar chemical properties. Forests on lands abandoned from agriculture 80-100 years before had slightly higher pH and nutrient concentrations than adjacent, uncleared forests, but these changes were small compared to environmental variation across the county.Main conclusions Despite differential use of lands according to their topography and soils, the substantial influence of accessibility and the relatively small scale of land-use decisions allowed for broad similarity among forest types. Thus, the topography and soil differences created by land-use decisions probably contribute little to landscape-level patterns of diversity. Subtle changes in forest Journal of Biogeography (J. Biogeogr.) (2005) 32, 439-452 ª 2005 Blackwell Publishing Ltd www.blackwellpublishing.com/jbi

Recovery of Forest Plant Communities in Post-Agricultural Landscapes

“…Recent forest soils may continue to reflect their agricultural history over 100 years after reforestation (Koerner et al 1997;Verheyen et al 1999;Dupouey et al 2002). Alternatively, as an equal number of studies have found, they may become broadly similar to ancient forest soils within that time (Kalisz 1986;Compton and Boone 2000;Flinn et al 2005). This regional variation can be difficult to predict because it depends on complex interactions between inherent soil fertility, the nature and duration of agricultural use, and time since abandonment.…”

“…A major caveat in interpreting environmental differences between ancient and recent forests, as well as the implications for plant communities, is that geographical patterns of land use and environmental variation are often confounded. Steeper slopes, poorer soils, and wetter areas are less likely to be cleared for agriculture and more likely to be abandoned (Foster 1992;Matlack 1997;Flinn et al 2005). Differences in environment and vegetation among current forest types may result from initial conditions rather than agricultural land use itself.…”

“…One way to control for pre-existing environmental variation is to focus on regions where past land use varies across an area homogenous in topography and soils (Motzkin et al 1996). Within more diverse landscapes, the effects of variation in prior conditions can be eliminated by selecting adjacent pairs of sites that share similar topography and soils, but that differ in history (Kalisz 1986;Singleton et al 2001;Flinn et al 2005).…”

Avaliação Das Relações Entre Os Parâmetros Da Modelagem Geomorfológica E a Cobertura Florestal No Noroeste Do Rio Grande Do Sul / Assessment of Relations Between the Geomorphological Modeling Parameters and the Forest Cover in the Northwest of Rs

“…al., 1999) e tem papel importante no manejo e restauração de ecossistemas (SWETNAM et al, 1999;LUNT e SPOONER, 2005;BALÉE, 2006). O uso da terra está frequentemente associado a aspectos físicos, morfológicos e fisiográficos das paisagens (FOSTER, 1992;FLINN et al, 2005;SIMONSON e JOHNSON, 2005) e, muitas vezes, é limitado pelas condições adversas de relevo, ou costuma ser intensificado quando o relevo é favorável para a agricultura (p.ex., plano). A interação entre uso da terra e relevo é um dos aspectos determinantes da configuração de uma paisagem.…”

“…A interação entre uso da terra e relevo é um dos aspectos determinantes da configuração de uma paisagem. Ao se associar o histórico de uso da terra às características geomorfológicas de uma região, é possível distinguir a contribuição de cada um desses fatores na determinação de padrões ecológicos, ou ainda, padrões resultantes da interação entre estes aspectos (FLINN et al, 2005;SIMONSON e JOHNSON, 2005;CINGOLANI et al, 2008).…”