Land use as a driver of soil fertility and biodiversity across an agricultural landscape in the Central Peruvian Andes

Abstract

Land use change and intensification in agricultural landscapes of the Andean highlands have resulted in widespread soil degradation and a loss in soil-based ecosystem services and biodiversity. This trend threatens the sustainability of farming communities in the Andes, with important implications for food security and biodiversity conservation throughout the region. Based on these challenges, we sought to understand the impact of current and future land use practices on soil fertility and biodiversity, so as to inform landscape planning and management decisions for sustainable agroecosystem management. We worked with local communities to identify and map dominant land uses in an agricultural landscape surrounding Quilcas, Peru. These land uses existed within two elevations zones (low-medium, 3200-3800 m, and high elevation, 3800-4300 m). They included three types of low-medium elevation forests (eucalyptus, alder, and mixed/native species), five pasture management types (permanent pasture, temporal pasture [in fallow stage], degraded pasture, high-altitude permanent pasture, and high-altitude temporal pasture [in fallow stage]) and six cropping systems (forage crops, maize/beans, and potato under four types of management). Soil fertility was evaluated in surface soils (0-20 cm) with soil physicochemical parameters (e.g., pH, soil organic matter, available nutrients, texture), while soil biological properties were assessed using the abundance and diversity of soil macrofauna and ground cover vegetation. Our results indicated clear impacts of land use on soil fertility and biological communities. Altitude demonstrated the strongest effect on soil physicochemical properties, but management systems within the low-mid elevation zone also showed important differences in soil biological communities. In general, the less-disturbed forest and pasture systems supported more diverse soil communities than the more intensively managed croplands. Degraded soils demonstrated the lowest overall soil fertility and abundance of soil macrofauna, but this may be reversible via the planting of alder forests. Our findings also indicated significant covariation between soil physicochemical parameters, soil macrofauna, and ground vegetation. This suggests that management for any one of these soil properties may yield unintended cascading effects throughout the soil subsystem. In summary, our findings suggest that shifts in land use across the landscape are likely to have important impacts on soil functioning and biodiversity.

Variation in Tree Community Composition and Carbon Stock under Natural and Human Disturbances in Andean Forests, Peru

“…Crop cultivation such as of beans, corns, and potatoes is popular in the agricultural landscapes. A recent study reported that rapid land use change including deforestation had a great impact on soil fertility and biodiversity, and threatened the sustainability of farming in this region [48]. Although crop cultivation and fire were significantly associated with community composition only in the NMDS analysis ( Figure 3) and not in GLMs for multivariate abundance data (Tables 1-4), it has been reported that Andean montane forests are suffering from human-induced fires which start in the flammable grassland region (locally called Puna) at relatively high elevation (>2000 m a.s.l.)…”

Agroecosystem patterns and land management co‐develop through environment, management, and land‐use interactions

“…As reported by farmers in the participatory community mapping, these patches of forest are often planted on already degraded land. Nevertheless, the fact that most of these patches of forest are still performing poorly after 20 or more years since establishment indicates that their potential to restore degraded land may be limited and that attention is needed to explore how best to encourage alternative mixed forestry for purposes of biomass production as suggested by de Valenc ßa et al (2017) and Hall et al (2012), rather than the planting of monoculture pine or eucalyptus patches of forest.…”

Soil Health Changes Over a 25-Year Chronosequence From Forest to Plantations in Rubber Tree (Hevea brasiliensis) Landscapes in Southern Côte d'Ivoire: Do Earthworms Play a Role?

“…This is particularly true in rubber tree landscapes presumably characterized by the successional replacement of land use and land cover that drive above and belowground interactions. This change also undermines the deliverance of soil-based ecosystem services which are driven by soil organisms among which soil macroinvertebrates play a critical role like any other land uses around the world (Spurgeon et al, 2013;Franco et al, 2016;de Valençia et al, 2017).…”