Changes in the spatial variation of soil properties following shifting cultivation in a Mexican tropical dry forest |
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Authors: | Lucy O Diekmann Deborah Lawrence Gregory S Okin |
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Institution: | (1) Department of Environmental Science, Policy and Management, University of California, Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720, USA;(2) Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA;(3) Department of Geography, UCLA, Los Angels, CA 90095, USA |
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Abstract: | The role of secondary vegetation in restoring soil fertility during shifting cultivation in the tropics is well known. Yet
the effect of secondary succession on the spatial patterns of soil properties has received little attention. To determine
whether changes in the plant community as a result of shifting cultivation affect the scale of spatial dependence for biologically
important soil nutrients, we sampled three dry tropical forest stands in Campeche, Mexico. These stands represented a gradient
of cultivation history: one mature forest stand, a forest fallow that had undergone one cultivation-fallow cycle, and a forest
fallow that had undergone two cultivation-fallow cycles. We used an analysis of semivariance to quantify the scale and magnitude
of spatial dependence for organic matter content (OM), phosphorus (P), potassium (K), and aluminum (Al) in each stand. The
scale of spatial dependence varied with cultivation history, but the degree of spatial dependence did not differ among stands.
In the mature forest P and K were autocorrelated over distances >7.5 m. In the forest fallows 48–88% of the variation in soil
P and K was autocorrelated over distances up to 1.1–5.1 m. In contrast, the range of autocorrelation for Al (∼2.5 m) did not
differ among stands. We conclude that shifting cultivation changes the range of autocorrelation for biologically important
soil nutrients at a scale that may influence plant growth. The finer scaled pattern of soil nutrients in forest fallows is
likely to persist with continued shifting cultivation, since fallows are cleared every 3–15 years. |
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Keywords: | Tropical dry forest Geostatistics Mexico Shifting cultivation Soil nutrients Spatial heterogeneity |
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