The effects of agricultural history on forest ecological integrity as determined by a rapid forest assessment method

Abstract

Forests are an important terrestrial biome, comprising large areas of the earth’s surface and providing important ecosystem services. Conservation efforts frequently focus on minimizing perceived threats to forests that could impact these services, but often without a clear understanding of the site specific factors that affect local forest composition, structure and threat magnitude. In this study, we examined the factors affecting forest ‘ecological integrity’ in a 334ha forest that includes mature forest remnants and areas recovering from agricultural activity. We developed a rapid upland forest assessment (RUFA) method to facilitate our examination of forest integrity since forest quality can vary at fine spatial scales (e.g., 100m) and time consuming assessment methods may not be feasible for many local conservation organizations. In general, we found that land use history and especially soil conditions associated with history were the primary factors affecting forest ‘ecological integrity’ (i.e. composition, structure and threat presence). In forests that developed after agricultural abandonment, soil pH significantly increased, while soil carbon and nitrogen content declined. This was associated with increased presence of invasive, early successional tree, shrub and herb species and a general lack of some structural components, such as the presence of light gaps, within the forest. Our results are discussed in light of conservation efforts that seek to enhance overall forest quality and how rapid assessment methods, such as the one presented here, can be used to further conservation objectives in forest systems.