Drivers of temperate woodland condition through time in an agricultural landscape

Abstract

Conversion of natural woodlands to grazing pastures is a major driver of biodiversity loss. In response to this threat, regenerative management approaches have been proposed to balance agriculture with biodiversity conservation. Yet rigorous experiments investigating the effectiveness of such approaches are rare. We used time‐series data from a broad‐scale experiment in south‐eastern Australian woodlands to explore the effects of agricultural practices and environmental factors on regeneration, bare ground, and native and exotic cover and richness. Our study included historical fertilization, three past grazing regimes (continuous, short‐conversion rotational, and long-conversion rotational), two present‐day grazing measures (grazing duration and stocking rate), and three environmental covariates (natural soil fertility, native woody cover, and rainfall). We found that fertilizer application was associated with altered trajectories of native overstorey cover, native plant richness, exotic cover, and bare ground. Changes in woodland condition also were associated with a combination of present‐day grazing and environmental drivers. Natural regeneration, native plant richness, and native herb cover were negatively associated with increased grazing intensity. Conversely, increased landscape‐scale native woody cover and local‐scale natural soil fertility were associated with increases in native overstorey cover and native plant richness and decreases in exotic cover and bare ground. Our results indicate that land‐use history, present grazing intensity, and landscape context alter woodland ecosystem responses to intervention. This may explain why some conservation actions fail to meet objectives. Our results indicate that the effectiveness of conservation actions can be improved by considering the combined influence of past and present agricultural management and landscape context on woodland condition.