Climate Change Benefits of Farmscaping in Yolo County
What is farmscaping?
"Farmscaping" refers to a broad range of management practices that involve planting various tree, shrub, and grass species within agricultural landscapes to maximize the ecosystem services provided to the adjacent farmland and the wider environment.
Vegetation sampling in Yolo County. Photo credit: Annie Young-Mathews
Farmscaping Practices Include:
- Reforesting rangelands and riparian corridors
- Planting hedgerows and windbreaks along field margins
- Installation of filter strips, grassed waterways and tail-water ponds
- Winter cover-cropping
Photo credit: Susan Ellsworth
What ecosystem services are provided by farmscaping?
- Establishes habitat for beneficial insects and animals (e.g. pollinators, natural enemies of insect pests)
- Buffers the drift of dust or pesticides and controls micro-climate by reducing or redirecting wind
- Stabilizes waterways and reduces runoff and soil erosion
- Prevents nutrients from entering waterways and improves water quality
- Uptake of excess nitrogen by vegetation can minimize nitrous oxide emissions which have a high global warming potential.
- Stores carbon in plant vegetation and soil
- Increases ecosystem biodiversity
- Adds to the aesthetic value of the agricultural landscape
What are the specific climate change benefits of farmscaping?
1. Carbon Storage and Greenhouse Gas Mitigation
One of the most common strategies for mitigating greenhouse gas emissions is to plant trees that remove carbon dioxide from the atmosphere as they grow. During photosynthesis, trees break apart carbon dioxide and incorporate the carbon into their wood while releasing the oxygen back into the atmosphere. Since trees and shrubs can store relatively large amounts of carbon in their biomass over the course of their life cycle, efforts to plant trees in rangelands, riparian corridors and around field edges is a viable means of "offsetting" emissions from other sources. Under California's Global Warming Solutions Act (AB 32), the state plans to implement a carbon market (i.e. cap-and-trade system) with protocols for the sale of carbon offset credits for activities such as forestry and urban forestry projects. Adapting these protocols to include farmscaping practices such as reforesting riparian corridors and rangelands is already under consideration.
Figure 1. Illustration of riparian zones in cropland and rangeland use types _
To do this, we must first determine how much carbon could be stored in our local landscape by adopting various farmscaping practices. A recent study by Young-Mathews et al. (2010) measured the amount of carbon present in both the soil and permanent vegetation (i.e. trees and shrubs) for 12 cropland and 8 rangeland sites throughout Yolo County. At each site, riparian zones were paired with adjacent agricultural fields that were either planted in row crops or grazed in the case of the rangeland field (Figure 1). Two findings of this study deserve note (Figure 2). First, riparian zones in rangelands stored nearly 2 times as much carbon per acre relative to the neighboring grazed field. Second, riparian zones in croplands stored less than those in rangelands, but still stored 25% more carbon than the adjacent cropped field. In both cases, virtually all of the difference in carbon storage was due to the amount of woody vegetation present. The carbon stored in woody vegetation accumulates gradually over time until the forest reaches maturity, at which point the amount of new carbon stored is approximately the same as that being lost through natural decomposition. Riparian forests in Yolo County generally take about 80 years to reach maturity, each year sequestering between 0.5 - 2.0 metric tons of carbon per hectare of forest (1 Mg = 1 metric ton) , .
Figure 2. Carbon storage in soil and woody vegetation for fields and riparian zones as found in both cropland and rangeland use types. This study was based on 20 riparian sites with adjacent fields all located in Yolo County _.
2. Biodiversity, Resilience and Adaptation
Climate change is expected to have a large impact on natural and agroecosystems both locally and globally. In response, farmscaping practices may help to mitigate loss of biodiversity by providing habitat for various plant, animal, insect, and microbial species. Young-Mathews et al. (2010) found increases in plant species diversity in riparian areas adjacent to rangeland and cropland areas in Yolo County. They also found that the diversity of soil organisms was dependent on aboveground productivity. Similarly, Smukler et al. (2010) found vegetation diversity to be the highest in riparian zones, hedgerows, and tail water ponds as compared to cropped areas. Distinct nematode and bacterial functional groups were identified and a greater earthworm biomass was found in the farmscaped areas as compared to cropped areas. The results from Smukler and Young-Mathews studies show that farmscaping can improve biodiversity. In addition to the intrinsic value of preserving habitat, biodiversity also contributes to multiple ecosystem functions. For example, biodiversity supports ecosystem stability and resilience, characteristics which enhance our capacity to adapt to climate change.
Farmscaping can help farmers manage pests by providing habitat for beneficial insects. Pest insects destroy crops by feeding on them or using them for reproduction, and beneficial insects are those that help to pollinate crops or prey on pest species. Hedgerows with high plant diversity support populations of beneficial insects, which in turn, help lower numbers of pest insects. A study by Long et al. (2001) found that hedgerows with native grasses and perennial shrubs hosted mostly beneficial insect species, whereas similar sampling in weedy vegetation showed a higher number of pest species. An earlier study by Long et al. (1998) links the presence of beneficial insects on hedgerow plantings to their presence on crop plantings up to 250 feet away. The studies by Long make two key points: 1) That hedgerow plantings attract significantly greater amounts of beneficial insects than pest insects, and 2) that these beneficial insects move onto nearby crops, where interaction with pests is likely. In this case, hedgerow plantings can be combined with integrated pest management solutions to help manage pests in addition to serving other roles as a farmscaping tool.
Figure 3. Beneficial insects observed on hedgerow plants _.
Figure 4. Pest insects observed on hedgerow plants _.
Figure 5. Distances beneficial insects traveled from hedgerow plantings _.
What are the practical constraints to successful farmscaping?
The creation of farmscaped areas such as hedgerows or reforesting riparian corridors requires some initial investment and maintenance. As of 2004, the typical cost for a 1500x15' hedgerow is $3,614 . Costs to consider include:
- Design (location, size, species composition)
- Site preparation (plowing, irrigation setup)
- Fertilizer or pesticide (may require research)
- Seeds and seedlings
- Barrier setup (tree tubes)
- Irrigation - first 2 years
- Weed removal and seedling protection
Few, if any, long-term costs are anticipated, as irrigation and weed removal costs are only scheduled for the first 2 years' establishment. Under certain conditions, irrigation and weed removal may be needed for longer than 2 years.
Figure 6. Cost breakdown by type for a 1500x15' hedgerow _.
How do I get involved with farmscaping activities in Yolo County?
For several decades in Yolo County, organizations such as the California Alliance of Family Farms (CAFF), the Audubon Society, and the Yolo County Resource Conservation District have been promoting an assortment of farmscaping practices. Below is a list of websites and resources that provide useful information regarding all aspects of farmscaping.
|||Young-Mathews, A., S. Culman, et al. (2010). "Plant-soil biodiversity relationships and nutrient retention in agricultural riparian zones of the Sacramento Valley, California." Agroforestry Systems 80(1): 41-60.|
|||Smukler, S. M., S. Sánchez-Moreno, et al. (2010). "Biodiversity and multiple ecosystem functions in an organic farmscape." Agriculture, Ecosystems & Environment 139(1-2): 80-97.|
|||Long, R., C. Pease, et al. (2001). Quantifying pest and beneficial insects in insectary hedgerows. University of California Sustainable Agriculture Research and Education Program. Yolo County, CA, California Tomato Research Institute; University of California Cooperative Extension.|
|||Long, R., A. Corbett, et al. (1998). "Beneficial insects move from flowering plants to nearby crops." California Agriculture 52(5): 4.|
|||Earnshaw, S. (2004). Hedgerows for California Agriculture. Davis, CA, Community Alliance with Family Farmers.|
|||Anderson, J. and R. Long (1999). Hedgerows: Turning Farm Waste Areas into Active IPM Life Cycles. Yolo County, CA, California Department of Pesticide Regulation.|