Agroforestry and Climate Change: Reducing Threats and Enhancing Resiliency in Agricultural

11/6/2014

Agroforestry and Climate Change: Reducing Threats and Enhancing Resiliency in Agricultural Landscapes

Assessment Prospectus

EXECUTIVE SUMMARY

Toral Patel-Weynand, USFS

An overview of assessment findings will be provided and will also serve as a summary for decision makers.

CHAPTER 1: Introduction

Michele Schoeneberger, USFS NAC; Gary Bentrup, USFS NAC; Toral Patel-Weynand, USFS; Shibu Jose, University of Missouri, Center for Agroforestry

The agroforestry technical report is a comprehensive scientific assessment of the capacity for agroforestry to provide mitigation and adaptation strategies to climate change. The assessment provides technical input to the National Climate Assessment (NCA) and serves as a framework for managing agroforestry systems in the United States. The report will provide technical input to the 2017 NCA developed by the U.S. Global Change Research Program (USGCRP). From a land use perspective, this assessment report will be the key technical document for the agroforestry sector. The report will address adaptation mechanisms from food security to carbon sequestration and will discuss social, cultural and economic aspects of agroforestry systems and the ability of these systems to provide multi-purpose solutions to impacts from climatic variability and change.

Climate disruptions to agricultural production have grown in the recent past and are projected to continue to increase in the coming decades, with negative effects expected on many crops and livestock. Current loss and degradation of agricultural services will continue without the implementation of innovative conservation methods.

Agroforestry, which is the intentional blending of agriculture and Working Trees to enhance productivity, profitability, and environmental stewardship, is an increasingly-applied method to improve sustainability of agricultural systems. The five widely recognized types of agroforestry in the United States include silvopasture, alley cropping, forest farming (also known as multistory cropping), windbreaks, and riparian forest buffers. As a management activity, agroforestry can increase the resiliency of agriculture and provide environmental benefits by protecting soil and water quality, providing wildlife habitat, allowing for diversified income, and sequestering atmospheric carbon.

An expanded, science-based application of agroforestry on America’s farms, ranches, and woodlands is essential for landscape-scale conservation in four focus areas in the United States: 1) enhancing water resources; 2) responding to climate change; 3) community-based stewardship; and 4) jobs to assist rural communities which contribute to increasing resiliency for food production and sustaining healthy agricultural and range lands, allowing for increased food production.

The assessment chapters synthesize scientific research in areas such as microclimate modification, habitat diversification, maintenance and protection of natural resource services, agroforestry systems and their impacts on island and tribal nations, accounting for goods and services provided by agroforestry systems and tools for adaptation and implementation.

CHAPTER 2: Reducing Threats and Enhancing Resiliency

Jim Brandle, University of Nebraska, Lincoln; Tom Sauer, ARS; Mike Dosskey, USFS NAC; Mike Gold, University of Missouri, Center for Agroforestry

2.1 Climate Change and Adaptive Capacity of U.S. Agriculture

The assessment of Walthall et al. (2012) concludes that it is very likely that climate is changing and will continue to change throughout 21st century. Temperatures will generally get warmer, producing warmer summer days and nights, especially in the interior western U.S. Precipitation patterns will change, and those changes will be spatially variable. For example, winters will be wetter in North & Central US; drier in southern U.S. Summers will be drier in Northwest and South Central U.S.; wetter in North Central and Eastern U.S. Springtime will be wetter in the Midwest and rainstorms will be more intense. Drought periods may become more prolonged.

The changes in climate patterns pose hazards for U.S. agriculture and land resources. Yield of crops and livestock will decline due to average climate and extreme weather events outside of optimum thresholds, and, due to expanded and shifting ranges of pests (insects, pathogens, weeds). Higher CO2 may act to increases crop growth (and that of weeds, too), but reduce quality of some crops. Indirect hazards include increasing soil erosion and water pollution, more extreme drought periods, and declining habitat quality to support current biodiversity.

New technologies will be needed to avoid significant disruptions in agriculture. The pace and complexity of changing conditions are likely to overwhelm current systems ability to adapt and sustain current levels of output in the long term (Walthall et al., 2012). Agroforestry is a strategy that can enhance adaptive capacity of agriculture for the numerous challenges posed by climate change.

2.2 Food Production and Food Security

(Mike Gold, University of Missouri, Center for Agroforestry; J.B. Friday, University of Hawaii Forestry Extension; Craig Elevitch, Agroforestry Net, Inc.)

Annual crops that currently represent the bulk of food and feed production in the U.S. are particularly vulnerable to the predicted changes in climate. Yields of annual crops are expected to decline over time which directly threatens food production and food security.

Agroforestry crop systems are perennial-based, multi-species mixes that are inherently more resilient to environmental stresses than annual cropping systems. They have a higher degree of species diversity, larger below ground root systems that hedge against climate extremes and create an ability to aggressively rebound from disturbance. Agroforestry crops such as fruits, nuts, and berries are food producing and resilient to climate extremes. Agroforestry systems simultaneously provide additional ecological services that annual crops do not, such as mitigating non-point source pollution, enabling biocontrol through crop and ecosystem diversity, and sustaining long-term soil fertility. Agroforestry crops may be especially well-suited to marginal lands, thereby enabling expansion of productive acres.

Major gaps in our knowledge base inhibit our ability to widely implement agroforestry systems, including: Optimizing agroforestry systems for marginal lands, selecting specialty food crops to match site and environmental conditions, long-term economic profitability analyses, and lack of supporting infrastructure (public and private sectors).

2.3 Microclimate Modification for Agricultural Production

(Jim Brandle, University of Nebraska, Lincoln; Sid Brantly, NRCS; Shibu Jose, University of Missouri, Center for Agroforestry)

Crop and livestock production and efficacy of production practices are dependent on predictable weather conditions. Increasing variability and frequency of “atypical” weather conditions threatens production. Temperature and precipitation patterns (late spring and early fall freezes, extreme hot or cold temperatures, storm events and drought influence field operations, productivity of crops and pastures and the health and well-being of livestock.

Windbreaks reduce wind speed which can mitigate weather extremes to benefit crops and livestock within the sheltered zones. Alley cropping systems also modify the microenvironment and can have both positive and negative effects on associated crops depending on the crop and tree species chosen. Silvopasture systems offer protection to livestock by reducing wind chill stress in winter and heat stress in summer and by increasing forage production, both leading to improved animal health and weight gain.

Most technical aspects of design and management are well-known as are the financial benefits of adoption. However, more research is needed into social factors of adoption that appear to inhibit widespread adoption.

2.4 Soil Resources

(Tom Sauer, ARS; Ranjith Udawatta, University of Missouri)

Climate change presents several direct and indirect stressors on soil resources. Gradual yet sustained changes in mean temperature and precipitation will produce subtle to significant changes in the biophysical functioning of soil systems. For example, nutrient cycling capability will be impaired due to changes in biomass production and macro- and micro-invertebrate species composition, especially in degraded or marginal soils that are already less resilient, further reducing their potential productivity. Larger precipitation events will cause greater soil erosion and more severe droughts will further impair soil productivity and soil biophysical functioning. Increasing demand for food and fiber production will encourage increasing amounts of external inputs to cropping systems in an effort to compensate for lost soil productivity, but impaired soil resources are less likely to efficiently utilize these increased inputs. Consequently, marginal and vulnerable lands will be increasingly converted to crop production.

A major benefit of agroforestry systems is the soil protection and resilience that perennial vegetation such as trees provide. Traditional cropping systems are heavily reliant on annual species which provide less soil protection and are much more vulnerable to weather extremes. Trees and associated perennial vegetation stabilize and protect soil from erosion and ameliorate heat and drought effects on the functioning of soil biological communities. Improved soil health enhances its capability to cycle nutrients, degrade pesticides, store moisture, and recover biophysical function after disturbances.

While much is known about the advantages of agroforestry over annual cropping systems for protecting and sustaining soil health and productivity, there is limited knowledge about how its effects on soil carbon cycling might contribute to net greenhouse gas production when compared to annual cropping systems.

2.5 Water Resources

(Mike Dosskey, USFS NAC; Ranjith Udawatta, University of Missouri; Diomy Zamora, University of Minnesota Extension)

Predicted climate changes will profoundly affect water supply and quality in ways that threaten crop and livestock production, infrastructure (e.g., transportation, water storage), and environmental quality (e.g., wildlife habitat, domestic consumption, and industrial and recreation uses). Reduced annual rainfall and longer drought periods, combined with higher evaporative demand and longer growing seasons will stress crops and livestock. More-frequent extreme rainfall events will increase soil erosion and flooding and damage infrastructure (e.g., roads, railways, bridges, reservoirs). Greater erosion and flooding will increase pollution by sediments and agro-chemicals in runoff. Increasing air temperatures will elevate water temperatures and degrade cool-water aquatic habitats.

Agroforestry practices can mitigate drought stress by promoting infiltration and soil storage of rainfall, controlling evapotranspiration of crops, and reducing heat stress on livestock (See also “Microclimate Control”). Enhanced infiltration also reduces field runoff from peak storm flows that cause erosion and floods which contribute to water pollution. Agroforestry buffers filter pollutants out of runoff water and protect soil from erosion (See also “Soil Resources”). Streamside trees provide shade which can limit the rise in water temperature. Technical feasibility to achieve these benefits is fairly well-established. The level of these benefits, however, is dependent primarily upon extent of adoption, which at this point in time is very low, and to a lesser degree their design for which improved tools are being developed. However, more research is needed into social factors of adoption that appear to inhibit widespread adoption.

2.6 Biodiversity

(Gary Bentrup, USFS NAC; Shibu Jose, University of Missouri, Center for Agroforestry)

Biodiversity provides ecosystem services that are critical in supporting agricultural production and will be impacted by climate change and extreme weather events. Insect pests are expected to increase due to longer growing seasons yielding more generations per year leading to pests developing greater resistance to insecticides. This will necessitate an ever more important role for biological pest control. More than 30 percent offood production relies on insect pollination, overwhelmingly provided by European honey bees which are experiencing declines compounded by climate change. Habitat quality and structure will shift under changes in temperature and precipitation requiring species to find suitable habitat in order to persist.

Agroforestry systems can support these ecosystem services by providing critical habitat resources for beneficial insects for biological pest control and for native pollinators to augment honey bee pollination. In addition, agroforestry practices can protect these valuable insects by reducing spray drift and providing refugia from pesticides. Habitat connectivity and refugia provided by the woody structure of agroforestry systems can facilitate animal and plant species persistence under climate change. Negative impacts from agroforestry systems may result due to providing habitat and dispersal corridors for invasive weeds, crop pests, and wildlife which may distribute food-borne pathogens into cropped areas. Proper planning and management can mitigate these potential impacts.

The general effectiveness of agroforestry practices to provide these services is documented but specific knowledge gaps remain. The level of these benefits is dependent on appropriate plant species selection and design of the agroforestry practices to optimize gains and minimize potential problems. In addition to technical concerns, economic information is needed to guide decision-making and tools for taking in account biodiversity considerations need to be developed.

2.7 Air Quality

(Adam Chambers, NRCS)

Increased temperatures and prolonged droughts will periodically increase the amounts of wind-blown dust in the air from agricultural sources and exacerbate health risks to livestock and people in rural and urban communities.

Agroforestry practices such as windbreaks and alley cropping reduce wind speeds near the ground to both reduce the mobilization of soil particles into the air and to promote its deposition out of the air. The perennial vegetation also stabilizes soil to resist the erosive force of wind.

2.8 Effects of Climate Change on Agroforestry Species

(Andrew Bell, Chicago Botanic Gardens; Jason Griffen, Kansas State University)

Climate change and climate variability will influence the health and growth of agroforestry species. Selection of hardy species will improve agroforestry success and minimize threats to tree health. In some regions, expected climate variability will greatly reduce the number of hardy tree species that can be used for particular agroforestry application. For example, temperature and moisture stress greatly limit the number of woody species available for agroforestry systems in the Great Plains and future climate scenarios indicate that stresses from weather extremes will become even greater. Furthermore, new insect (e.g., emerald ash borer) and disease (e.g., pine wilt) threats will also affect the choices. How we select and evaluate these potential species is key to successfully implementing agroforestry practices not only in the Great Plains but in other regions as well.

CHAPTER 3: Agroforestry Accounting (Mitigation)

Michele Schoeneberger, USFS NAC; Grant Domke, USFS; Toral Patel-Weynand, USFS; Marlen Eve, USDA Climate Change Program Office

3.1 Introduction

(Michele Schoeneberger, USFS NAC; Grant Domke, USFS; Toral Patel-Weynand, USFS; Marlen Eve, USDA Climate Change Program Office)

Temperate agroforestry is recognized as a viable agricultural option for mitigating greenhouse gas (GHG) emissions in the U.S. and Canada (CAST 2011, Schoeneberger et al. 2012). Agroforestry contributes to agricultural GHG mitigation activities by 1) sequestering carbon (C), 2) reducing GHG emissions, and 3) reducing fossil fuel and energy usage. The potential contributions have been estimated to be large (Brandle et al. 1992, Udawatta and Jose 2011), however, reliable and accurate GHG accounting within these systems is needed to assess the extent and value of the contributions to inform management, program and policy decision making. Agroforestry represents a unique case within C accounting as it encompasses both forest and agricultural components, along with many combinations of their respective management activities (i.e., fertilization, harvesting, and tillage). While current methodologies are relatively well defined for forest and cropping/grazing systems, those for agroforestry are only beginning to be formulated. This Chapter will address what accounting approaches and methodologies are being pulled from the forestry and agricultural sectors to build a C accounting system within agroforestry and what needs to be addressed in the future to give a more complete accounting of C sequestered and the net GHG dynamics in these spatially and temporally complex systems.