Ecological intensification: harnessing ecosystem services for food security, Bommarco et al. 2013

Compendium Volume 3 Number 1 July 2019

This review examines the concept of ecological intensification as a way to increase global food production by enhancing the ecological functionality of farmland.

We present ecological intensification as an alternative approach for mainstream agriculture to meet [future climatic, economic and social] challenges. Ecological intensification aims to match or augment yield levels while minimizing negative impacts on the environment and ensuing negative feedbacks on agricultural productivity, by integrating the management of ecosystem services delivered by biodiversity into crop production systems [Bommarco 2013: 230].

The idea of ecological intensification stems from the concept of ecosystem services, which refers to the benefits humans derive from ecosystems. These services are grouped into four types: supporting (such as soil formation by microorganisms), regulating (such as pest control, crop pollination, climate regulation and water purification), provisioning (such as food, fiber, fuel and water) and cultural (such as education, recreation and aesthetic).

Ecological intensification is based on managing service-providing organisms that make a quantifiable direct or indirect contribution to agricultural production [Bommarco 2013: 230].

The authors specify that: “crop yield has been defined as a provisioning ecosystem service, but the yield that is harvested in a given location depends largely on several supporting and regulating services” [Bommarco 2013: 231], such as soil production and pollination. And they note that these supporting and regulating ecosystem services underpin all agricultural production, including high-input industrial systems. For example, no matter how healthy and productive a crop is, yield will suffer if it’s not well pollinated, an observation consistent with Liebig’s Law of the Minimum. “One or several of these services can limit production and, even if all other services are optimized, no or little additional output will be attained until this ecosystem service shortfall is addressed” [Bommarco 2013: 231].

Beyond fulfilling a simple mechanistic role as a medium for crops to root into, soils provide multiple ecosystem services that support crop growth.

Soil services that promote plant growth include pest and disease regulation, nutrient flow, and soil formation and structure that allow for root penetration, gas exchange, water retention, and erosion control. These processes are mediated by an immense, diverse, and largely unexplored biological community of mainly bacteria and fungi, but also protozoa, nematodes, arthropods, and earthworms [Bommarco 2013: 232].

Soil services that promote plant growth include pest and disease regulation, nutrient flow, and soil formation and structure that allow for root penetration, gas exchange, water retention, and erosion control. These processes are mediated by an immense, diverse, and largely unexplored biological community of mainly bacteria and fungi, but also protozoa, nematodes, arthropods, and earthworms [Bommarco 2013: 232].

The management practices required to activate and optimize these soil services involve increasing soil organic matter (SOM) and diversifying crop rotation.

Ecosystems also provide the regulating services of biological pest control and crop pollination. Natural pest control can enhance or maintain yield even in pesticide-based production systems. However, the overuse of pesticides can severely damage ecosystem-based pest regulation, leading to pest resurgence or crop production system collapse. Strategies to enhance pest-predator populations “include landscape-level diversification by creation or conservation of natural and resource-rich habitat, combined with directed or diversified crop rotation and decreased pesticide pressure” [Bommarco 2013: 234]. Similarly, “pollinators can be promoted at the field or farm scale by enhancing floral resources and nesting sites, thereby potentially reducing the part of the yield gap caused by pollination deficits” [Bommarco 2013: 234].

In conclusion, the authors recommend that ecological intensification strategies increasingly replace conventional, industrial practices in developed countries, where the average yield potential has largely already been met, while using ecological intensification in combination with conventional strategies to close the yield gap in parts of the world where yields are low.

Bommarco, Ricardo, David Kleijn & Simon Potts, 2013, Ecological intensification: harnessing ecosystem services for food security, Trends in Ecology and Evolution 28:4, https://www.sciencedirect.com/science/article/abs/pii/S016953471200273X.

For the full PDF version of the compendium issue where this article appears, visit Compendium Volume 3 Number 1 July 2019