Alley cropping with short rotation coppices in the temperate region: A land-use strategy for optimizing microclimate, soil organic carbon and ecosystem service provision of agricultural landscapes

Abstract

Conventional agricultural practices have been associated with negative effects, such as reduction of soil fertility, pollution of surface and groundwater and loss of biodiversity and ecosystem services (ES). To mitigate these effects, while sustaining high levels of crop production, innovative land-use practices are necessary. A promising land-use approach are alley cropping systems (ACS) with short rotation coppices, which are agroforestry systems, that combine the cultivation of conventional agricultural crops with fast-growing trees to produce biomass for energy purposes at the same time on the same piece of land. In the presented study, the effects of trees planted in ACS on agricultural land in Central Europe on microclimate, on soil organic matter (SOM) and on the provision of ecosystem services (ES) were elaborated, based on a review of relevant literature and results of recent research projects. The outcomes suggest that, due to their structural complexity, ACS can be more efficient regarding main microclimatic factors than either crop or tree monocultural systems. As a main factor, wind protection by the hedgerows in ACS was identified. Other microclimatic factors, such as light, temperature or evaporation, were also clearly influenced by the presence of trees; however, occurring interactions were often complex, and cause-effect relations were difficult to ascertain. A further outcome is that planting trees on agricultural sites potentially increases soil organic carbon (SOC) stocks, which can be considered as a main indicator for soil humus and soil fertility. However, it became evident that, in addition to the depth dimension (30 cm sampling depth can be considered as insufficient), the dimension of time needs to be taken more strongly into account. The authors suggest a division of the lifetime of agricultural trees in an initial (SOC stocks may decrease), a transitional (stocks approach steady state; SOC distribution pattern in the soil may change) and a steady-state phase (no major changes in stocks or distribution patterns) when interpreting effects of trees on SOC. Subsequently, in the attempt to value the effects of ACS on crop productivity and soil, suitable and transferable methods for the assessment of ES were discussed. It was demonstrated that the provision of ES from ACS was higher than from conventional agriculture and that ACS can increase productivity while sustaining high levels of SOC. Summarizing, the results suggested that ACS - if designed and managed appropriately - may function as a practical and diverse tool to mitigate negative effects of agricultural production.