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Claire Kremen, University of California, Berkeley

Jan 28, 2015
Dr. Claire Kremen

Dr. Claire Kremen

Much of your research focuses on biodiversity conservation within agricultural landscapes. Why do you focus on these environments?

Formerly, I worked primarily on setting up protected areas in the tropics, specifically in Madagascar, to protect imperiled and unique biodiversity. However, while I still believe deeply in the need to establish and maintain protected areas as repositories of biodiversity, I became convinced that these protected areas would never survive unless we could develop societies based on environmental, economic and social sustainability. Agriculture takes up nearly half of the terrestrial land surface—that’s why it’s so important to seek sustainability in agricultural landscapes. With such a large land area, the agricultural regions are also critical regions in which to conserve biodiversity, and if managed well, can serve as a favorable matrix around protected areas.

A native plant flowering hedgerow field margin – planted to enhance pollinator and natural enemy populations.  Photo by L. M’Gonigle.

A native plant flowering hedgerow field margin – planted to enhance pollinator and natural enemy populations. Photo by L. M’Gonigle.

What are some of the projects that are currently ongoing in your lab?

We work a great deal on understanding how diversification practices, both on the farm and in the landscapes surrounding the farm, affect critical “ecosystem services” in farming, like pollination, pest control and disease control. Currently we have two major projects, both in landscapes in California. In the region just north of the Bay Area (Solano, Yolo and Colusa Counties), we study how a single farm management technique—the integration of sequentially flowering, native plant hedgerows—affects pollinators, natural enemies and the services they provide of crop pollination and pest control. In the Central Coast region (Santa Cruz, Monterey and San Benito counties), we are investigating how a suite of diversification practices influences a multitude of ecosystem services (including pollination, pest control, disease control, water and air quality, and soils); how these practices affect the farm economy; how farmers perceive the costs and benefits of these practices; and what market and regulatory factors promote or prevent adoption of diversification practices.

Diversfied farming techniques can maintain and regenerate ecosystem services to agriculture.

Diversfied farming techniques can maintain and regenerate ecosystem services to agriculture.

What are some farming techniques that can increase diversity on farms?

I like to think of biological diversity across organizational scales (genetic to species to community to landscape), spatial scales (plot to field to surrounding landscape) and temporal scales (within year to across years). There are many practices that enhance biodiversity (and promote ecosystem services) at one or several of these scales. Planting a crop that has great genetic and/or varietal diversity can enhance pest and disease control, for example. Intercropping—planting more than one species together—can enhance nutrient and water use efficiency, create

synergies such as when one crop species fixes nitrogen that the other crop species can use, promote pest and disease control, and enhance yields. Integration of compost into the soil feeds the below-ground community (from microbes to millipedes) and literally creates sub-surface habitat for a myriad of organisms, enhancing diversity. Creation of a rich soil organic matter than serves as a sponge (promoting the uptake and storage of water so that heavy rainfalls don’t erode soils and pollute waterways with nutrients) and the stored water mitigates the effects of drought. Cover-cropping and crop rotation enhance the plant diversity on the farm over time, and lead to multiple benefits, including enhancement of soil fertility, nutrient and weed management, and interruption of cycles of pests and diseases. Finally, hedgerows and nearby natural habitats provide habitat for pollinator and pest control agents.

Diverse crop plantings also attract a wider diversity and greater abundance of pollinators. Photo by C. Kremen

Diverse crop plantings also attract a wider diversity and greater abundance of pollinators. Photo by C. Kremen

Organic farming is considered more environmentally friendly yet sceptics often claim that it cannot ‘feed the world.’ Is environmentally friendly farming synonymous with low yields?

I don’t believe so. There are a number of examples of organic or other agro-ecological farming systems that achieve yield parity or enhanced yields compared to industrial (chemically intensive) farming systems. We need to build from these examples. What are these growers doing right?  Or, when there are large yield gaps, what could be done differently for those specific crops in those farming regions?

We also need to recognize that yield isn’t everything. What if we do have slightly reduced yields?  Isn’t it more than made up for by farming in a way that won’t harm the workers on the farm, the co-habiting or neighboring wildlife, and our ability to feed future generations?  The truth is, we waste so much food (30-40%) annually. If we could cut just food waste by half, we’d already make up for any yield losses that occur when farmers care for the environment, rather than simply maximizing yields

Netting pollinaotrs at one of our hedgerow sites. Photo by C. Kremen

Netting pollinaotrs at one of our hedgerow sites. Photo by C. Kremen

Is all organic farming equally beneficial to biodiversity?

There are two aspects to my answer.

First, there are a wide variety of styles of organic farming. Some organic farms these days are minimally organic. They don’t use synthetic fertilizers or pesticides, but they may still practice monoculture farming and use methods of pest control that are highly energy intensive (such as vacuuming pests) or simply substitute for the synthetic inputs (i.e., use organic pesticides). Such farms are likely to harbor less biodiversity (and benefit less from those services that some components of biodiversity provide) than farms that base their soil fertility and pest control on the integration of a suite of diversifying practices.

However, farming systems in general, whether they are organic or conventional, are not going to support all of biodiversity. There are some species that simply only exist in natural or semi-natural environments. So we need to protect habitat for these species also.

 

What types of practices can organic farmers utilize to increase their yields?

Our recent meta-analysis suggests that complex rotations (including cover-cropping) and multi-cropping (growing multiple crops in the same field) both increase yields. Our analysis, however, brought

Stink bug eggs placed in fields next to and without hedgerows to monitor pest control on tomato. Photo by C. Kremen

Stink bug eggs placed in fields next to and without hedgerows to monitor pest control on tomato. Photo by C. Kremen

together a wide variety of studies on different crops in different regions. The common factor was that each study had to compare an organic system against a conventional one. Although we had a lot of studies and observations within those studies to work with, once the data get parsed and parsed into finer lots in order to identify the utility of a given technique, one finds that there are relatively few studies to work with, reducing our statistical ability (i.e., power) to detect differences. Thus, while our meta-analysis did not suggest that other farm management practices also reduce yield gaps, we know from individual studies, especially long-term ones such as those conducted at the Rodale Institute, that there are many other important techniques that can boost yields by reducing damage from pests, competition with weeds and losses due to diseases, as well as managing soil fertility and nutrient and water use, and maintaining resilience in the face of extreme weather events.

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One Response to “Claire Kremen, University of California, Berkeley”

  1. A. Alp-Ercelan says:

    Organic farming is considered more environmentally friendly yet sceptics often claim that it cannot ‘feed the world.’ Is environmentally friendly farming synonymous with low yields?

    I don’t believe so. There are a number of examples of organic or other agro-ecological farming systems that achieve yield parity or enhanced yields compared to industrial (chemically intensive) farming systems. We need to build from these examples. What are these growers doing right? Or, when there are large yield gaps, what could be done differently for those specific crops in those farming regions?

    We also need to recognize that yield isn’t everything. What if we do have slightly reduced yields? Isn’t it more than made up for by farming in a way that won’t harm the workers on the farm, the co-habiting or neighboring wildlife, and our ability to feed future generations? The truth is, we waste so much food (30-40%) annually. If we could cut just food waste by half, we’d already make up for any yield losses that occur when farmers care for the environment, rather than simply maximizing yields