Ecological network analysis to link interactions between system components and performances in multispecies livestock farms
Résumé
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 can
enhance their performance by increasing the level of interactions between system components. We therefore performed an
ecological network analysis to characterize both within-farm and farm-environment interactions. Flows were expressed on an
annual basis according to the quantity of biomass exchanges multiplied by nitrogen content. Seventeen organic farms were
surveyed in French grassland areas, each associating beef cattle with either sheep, pigs, or poultry. The ecological network
analysis was then coupled with the assessment of farm economic, environmental, and social performances. A hierarchical
clustering 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, can
limit the implementation of a homogeneous flow network within the system. A higher level of within-system interactions did not
lead to better farm economic, environmental, and social performances. Systems with large monogastric production enterprises
were highly dependent on inputs, which led to less homogeneous flow networks and a poor farm nitrogen balance without
gaining economic efficiency. Managing a complex system with a dense and complex flow network did not appear to increase
farmers’ mental workload. To our knowledge, this study is the first to quantify farm-scale interactions using ecological network
indicators in temperate livestock farms and to analyze the links between farm performance and operating processes. The
ecological 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
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