What evidence exists on the impact of agricultural practices in fruit orchards on biodiversity? A systematic map

BACKGROUND: Biodiversity loss, partly due to intensification of agriculture, has become a global issue. In this context, fruit producers have been looking for nature-friendly production methods. By reducing intensive pesticide use and enhancing orchard management, they aim to create habitats suitable for beneficial organisms. Fruit production, especially in low-stem orchards, requires several interventions (plant protection, tillage, greenwork) throughout the year, each of them representing a disturbance. Thus, an expert system that evaluates and aggregates the impact of individual farming activities on a set of biodiversity indicators would be a valuable tool for developing new, less biodiversity-damaging scenarios. This expert system should be based on expert knowledge and scientific evidence. Surprisingly, our literature searches suggested that international journals contain few publications on the impact of most practices (except pesticide use) in orchards on biodiversity in general and beneficial organisms in particular. However, in the last decade, an increasing number of published articles have pointed out the rising importance of biodiversity in life cycle assessment. We therefore compiled and structured the available evidence to (1) assess the state of research on discrete biodiversity indicators and agricultural practices, (2) identify the literature relevant for assessing production impact and habitat suitability for supporting biodiversity and (3) provide a wide-ranging overview of existing evidence of the impact of agricultural practices in fruit orchards on biodiversity. METHODS: A systematic literature search was performed in scientific journals, agronomy magazines and across the internet in English, German and French. The main reviewer followed a step-by-step eligibility scheme that was validated by a Kappa test between two reviewers. Additionally, a third reviewer checked a subset of articles. We mapped a large range of parameters, which were structured in code sets. To compute a study validity assessment, we used 13 parameters that reflected the relevance of each article to the impact of agricultural practices in fruit orchards on biodiversity indicator species groups. RESULTS: The search returned 947 included articles. The map identified major differences in the attention given to different indicators and practices over time, ranging from closely investigated (clusters) to neglected (gaps)—e.g. spiders and birds or amphibians and reptiles, respectively. The majority of studies were short-term surveys, mainly done in low-stem orchards. Main areas studied were Western Europe and Eastern North America. The resulting database is presented along with descriptive statistics of the distribution and abundance of evidence across time, interventions and outcomes. CONCLUSIONS: The current systematic map reveals that rigorous and comprehensive investigations on the suitability of orchards as perennial habitats for wildlife, run on the long-term and following a holistic approach, are still basically lacking. Although evidence base on orchard management effects on particular organisms has grown over the past two decades, information to develop reliable close-to-nature management tools and strategies is insufficient. The implications for policy and research suggest that—in view of worldwide biodiversity loss, which may cause a major threat for food production—a better understanding of the role played by orchards and their management in agricultural landscapes for biodiversity is required.