Ecological network analysis to link interactions between system components and performances in multispecies livestock farms

Summary

Organic farming relies on ecological processes to replace chemical inputs, and organic farmers have developed various strategies,including several forms of diversification, to remain viable. Herein, we hypothesized that diversified organic farming systems canenhance their performance by increasing the level of interactions between system components. We therefore performed anecological network analysis to characterize both within-farm and farm-environment interactions. Flows were expressed on anannual basis according to the quantity of biomass exchanges multiplied by nitrogen content. Seventeen organic farms weresurveyed in French grassland areas, each associating beef cattle with either sheep, pigs, or poultry. The ecological networkanalysis was then coupled with the assessment of farm economic, environmental, and social performances. A hierarchicalclustering on principal components distinguished five groups of farms based on farm and herd size, presence of monogastrics,percentage of crops in the farm area, and system activity indicators. A large farm size, in terms of area or number of workers, canlimit the implementation of a homogeneous flow network within the system. A higher level of within-system interactions did notlead to better farm economic, environmental, and social performances. Systems with large monogastric production enterpriseswere highly dependent on inputs, which led to less homogeneous flow networks and a poor farm nitrogen balance withoutgaining economic efficiency. Managing a complex system with a dense and complex flow network did not appear to increasefarmers’ mental workload. To our knowledge, this study is the first to quantify farm-scale interactions using ecological networkindicators in temperate livestock farms and to analyze the links between farm performance and operating processes. Theecological network analysis thus potentially provides a common framework for comparing a wide range of livestock farms.Given the variability of multispecies livestock farms, a larger database will be used to extend our conclusions