A workshop on Biodiversity and Resilience of Ecosystems will be held in Montpellier on 7-8 March under the joint auspices of Bioversity International and CIRAD, the French agricultural research for development centre. The workshop is one of several preliminary events leading up to the Resilience 2014 conference. In this blog post Fabrice DeClerck, leader of WLE’s theme on ecosystem services and resilience, reflects on agrobiodiversity and resilience.
On a recent plane trip I was reading a book on how animals work, an engineering perspective on ecological form and function. My neighbour, a well-built ex-marine of Jamaican heritage, peered over with evident curiosity and we started to chat in a conversation that moved swiftly to the role of biodiversity in global systems, and particularly in ensuring system resilience. This neighbour, a securities analyst for a Dutch internet company, immediately understood the issue, and the dilemma – monocultural landscapes are akin to having a single password (your birthday) for all your online activities: computer, email, bank accounts, etc. Crack one, you’ve cracked them all.
We all deplore constant reminders to change passwords, to have a different password for each application, to have passwords that include symbols and numerals. But we all also know the risk of depending on a single password – and our vulnerability to prowling internet pests and diseases. Why should we expect anything different for agriculture?
Agrobiodiversity is central to maintaining agroecosystem health, and understanding how to harness these contributions is a critical element in ensuring agricultural sustainability. One of the many system services that agricultural biodiversity provides is to help regulate pests and diseases, the focus of much research. Doing some of that research is Dr Rose Nankya, National Project Manager for the Pest & Disease component of the Agrobiodiversity & Ecosystem Services Programme at Bioversity International. Rose is based in Kampala, Uganda, where her research is demonstrating how the conservation and use of crop genetic diversity can control pests and diseases in support of sustainable agriculture.
The work in Uganda is part of a four-country effort that is beginning to show clear results. In Uganda and China, as the number of varieties in a farmer’s field increases, the damage caused by specific pests and diseases decreases. What is more striking, according to Rose Nankya, is that the variance of disease damage also goes down as diversity increases. While monocultures may have a winning crop one year, damage can be much greater the following year as pests and diseases change. Maintaining crop diversity in their production system enables resource-poor farmers to become more resilient to fluctuations in pests and diseases, increases their capacity to adapt to unpredictable environmental changes, and reduces their dependence on expensive agrochemicals which, while effectively reducing pest and disease outbreaks, can cause harm and reduce the resilience of the agroecosystem.
The evidence in favour of managing agrobiodiversity is mounting, but significant challenges remain in translating greater agricultural biodiversity into economic empowerment for farmers. Polycultures, multiple crop farms or fields, can be more labour intensive to manage, and require farmers to interact with multiple markets. Increasing diversity in a single field or farm is not the only option however, and the impacts of increasing agrobiodiversity may be even greater when whole landscapes are managed as diversified mosaics of fields, farms, and gardens.
Over-reliance on a single crop species, particularly at large scales, threatens food security in the same way that over-reliance on a single password threatens computer security. Newly-developed varieties may be able to resist pests and diseases, but growing them over a large area poses two risks. First, a large area of genetically similar plants puts more pressure on pests and diseases to mutate into new forms that can overcome the resistance. And secondly, once the pest or disease has broken the password, it can attack all the plants in the area, resulting in devastating epidemics.
In this context, conserving agrobiodiversity in situ -- on the farm -- is akin to ensuring multiple and regularly changing passwords. Unfortunately, current trends are driving the rapid disappearance of local species and varieties, simplifying security measures. Genebanks – ex situ conservation -- provide a fallback position, but in situ conservation allows varieties to continue to evolve and adapt in response to pests and diseases and all the other factors that impinge on a plant’s survival.
The research of Rose Nankya and others in the team helped me to explain to my neighbour on that flight how convinced I am that @gr0b10d1v3r$1ty is the password to sustainable food security.