Conversion of deciduous forest to silvopasture produces soil properties indicative of rapid transition to improved pasture

Abstract

Differences in soil properties between forests and pastures have been well documented in the literature, especially under coniferous forests. However, since nearly all of these reports have been time-point comparisons, utilizing long-term pairedsites, properties of transitional states and time of their appearance can only be inferred at present. In this study, a deciduous forest ecosystem was converted to a silvopasture ecosystem by tree thinning, fertilization, and sheep incorporation of seed and forest litter. After 2 years, topsoil (0-15 cm) physico-chemical properties, particularly P fractions, and phosphatases were monitored over the growing season in these ecosystems, and a nearby pasture ecosystem. Initially, before spring vegetative growth, differences were found for pH, exchangeable cations and soil moisture, most of which could be explained by management history. Compared to forest, organic-C (C o ) and organic-N (N o ) concentrations were reduced in silvopasture by 17 and 9%, respectively, indicative of substantial litter decomposition. Most values for all these physico-chemical properties for silvopasture were intermediate between forest and pasture, and generally remained so throughout the growing season. Initial total P (TP t ), organic-P (TP o ) and inorganic-P (TP i ) concentrations were generally as anticipated for the forest and pasture. Silvopasture, however, had 36 and 23% greater TP o than forest and pasture, respectively, presumably due to fertilizer-P immobilization induced by incorporation of forest litter. Total P components remained essentially constant over the growing season in all ecosystems, with the exception of pasture, likely due to high forage TP i uptake. Bray I-extractable-organic-P (BrP o ) and bicarbonate-extractable-organic-P (BiP o ) concentrations, although consistently highest in the forest and silvopasture soils, were not reflective of the increase in TP o under silvopasture. Acid phosphatase (PMEac) activities were highest in spring in all the ecosystems, then gradually declined to typically 25-50% initial activities. Alkaline phosphatase (PMEal) activities showed a broadly-similar pattern, with exception of forest and silvopasture soils, which exhibited low activities throughout the season. For the entire data set, PMEac and PMEal activities were poorly correlated with TP i, BrP i , and BiP i . These results demonstrate that conversion of forest to silvopasture results in soil changes indicative of its rapid transition to pasture and that an increased P o reservoir results that should be taken into account in fertilizer-P recommendations for temperate silvopastures.

Nitrate and fecal coliform concentration differences at the soil/bedrock interface in Appalachian silvopasture, pasture, and forest

“…Other studies have found that trees are able to capture much of the NO 3 -N that leaches past the herbaceous root systems in SP and agroforestry buffers (Huxley et al 1994;Schroth 1995;Udawatta et al 2002;Dougherty et al 2009). Staley et al (2008) found that soil chemical characteristics of these same SP sites were rapidly approaching pasture-like conditions, but they did not study NO 3 -N. Over time, SP NO 3 -N might be expected to approach the higher concentrations found in CP because of fertilizer amendments needed for forage growth, but regression analysis of NO 3 -N concentration versus time failed to show any movement in that direction. The higher fall NO 3 -N concentrations in CP and HF are probably related to return of N with leaf fall (Muller and Martin 1983) in HF and senescence of white clover (Whitehead 1995) in CP (see Fig.…”

“…The rate and magnitude of changes are unknown. Staley et al (2008) found that conversion of deciduous forest to silvopasture (SP) resulted in soil chemistry changes indicative of rapid transition to improved pasture. Surface litter changes and remnant macropores in SP recently established from deciduous forest resulted in changes in organic carbon transport to the soil/ bedrock interface (Boyer and Neel 2007).…”

Establishment and production from thinned mature deciduous-forest silvopastures in Appalachia

“…In Appalachia many soils are highly weathered and shallow. Silvopasture soil pH for the top 15 cm was 5.5, having increased from 4.7 prior to liming, while in pastures managed for many decades the pH was 6.8 (Staley et al 2008). Bray I extractable soil P was also significantly higher for pasture compared to silvopasture with values of 35.8 and 27.7 mg kg -1 , respectively compared to 6.1 mg kg -1 for silvopasture prior to fertilization.…”

The pool of organic carbon in the soils of Russia

“…Spatial distribution of particular land use types and ecosystem disturbances were obtained from the land cover map of Russia [45]. Published data were used to find correction coefficients for ecosystem disturbances (e.g., for the use of grass lands as pastures) [3,9,18,20,33,38,40,46]. The transformation of undisturbed steppe ecosystems into pastures leads to a decrease in the SOM pool in litter by 61%; the amount of carbon in the 1-m-thick soil layer is reduced by 25%.…”