Cropland physical disturbance intensity： plot-scale measurement and its application for soil erosion reduction in mountainous areas

Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers'management behavior.The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity(CLDI)to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas.The study was based on both plot survey and household interview data,collected from six typical catchments in mountainous areas of southwestern China.Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index.The rough set theory was referenced to avoid subjectivity during weight allocation.The results show that conventional tillage,deep fertilization,and manual weeding are the main causes of cropland soil erosion,whereas manure application in combination with seasonal fallow reduces soil erosion.Different crop types as well as cropland location factors determine the spatial pattern of CLDI.Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI,and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance.These results are critical to help better protect rural environments in mountainous areas.Based on the results,methods to reduce cropland soil erosion are suggested.

Effects of firewood harvesting intensity on biodiversity and ecosystem services in shrublands of northern Patagonia

Background: Forest management has historically focused on provisioning of goods (e.g. timber, biomass), butthere is an increasing interest to manage forests also to maintain biodiversity and to provide other ecosystemservices (ES).Methods: We evaluated the effects of firewood harvesting intensity on biodiversity and different ES in threecontrasting shrubland sites in northern Patagonia (Argentina). At each site, four harvesting treatments, representingvarious levels of harvest intensity, were randomly assigned to eight permanent sample plots of 31.5m× 45 mduring 2013–2014.Results: We found that the effects of increasing harvesting intensity on plant diversity changed from negative topositive (and from nonlinear to more linear responses) with increasing site productivity. Harvesting intensityshowed contrasting effects on variables related to fire protection ecosystem service, since it reduced fuel amount(potentially reducing fire spread) but also reduced live fuel moisture content (potentially increasing flammability) atthe three sites. Two variables related to soil formation and protection ES, leaf litter cover and aerial soil cover,decreased with harvesting intensity at the three sites.Conclusions: We conclude that shrubland management for firewood production may enhance biodiversity withoutcompromising certain important ES. The intensity of harvesting should be determined according to site conditionsand forecasted impacts on biodiversity, fire and soil formation and protection.

Differences in Soil Microbial Biomass and Activity for Six Agroecosystems with a Management Disturbance Gradient

Different management practices in six agroecosystems located near Goldsboro, NC, USA were conducted including a successional field (SU), a plantation woodlot (WO), an integrated cropping system with animals (IN), an organic farming system (OR), and two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT) to examine if and how microbial biomass and activity differ in response to alterations in disturbance intensity from six land management strategies. Results showed that soil microbial biomass and activity differed, with microbial activity in intermediately disturbed ecosystems (NT, OR, IN) being significantly higher (P ＜ 0.01) than systems with either high or low disturbance intensities. There was also a significant and a highly significant ecosystem effect from the treatments on microbial biomass C (MBC) (P ＜ 0.05) and on microbial activity (respiration) (P ＜ 0.01), respectively. Multiple comparisons of mean respiration rates distinctly separated the six ecosystem types into three groups: CT ＜ NT, SU and WO ＜ OR and IN.Thus, for detecting microbial response to disturbance changes these results indicated that the active component of the soil microbial community was a better indicator than total biomass.