Effects of Habitat Heterogeneity on Crop Yield and Biodiversity

Progress report for GW19-199

Project Type: Graduate Student
Funds awarded in 2019: $24,971.90
Projected End Date: 07/31/2022
Grant Recipient: 1992
Region: Western
State: Montana
Graduate Student:
Major Professor:
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Project Information


Agricultural ecosystems comprise roughly half of the global land surface and are faced with the competing tasks of feeding a growing population and conserving global biodiversity. Agriculture has often been viewed as a primary driver of habitat fragmentation and biodiversity loss, but recent studies have questioned the habitat-matrix paradigm with findings of positive relationships between landscape configurational heterogeneity and biodiversity in agricultural landscapes. Current research suggests the adoption of a mosaic landscape matrix paradigm, in which landscape heterogeneity enhances biodiversity with neutral or positive effects on crop yield. This study uses midfield islets to examine habitat heterogeneity and the effects on crop yield and biodiversity in farmland. Precision agriculture data is used to create yield maps that enable farmers to identify low-producing areas in their fields that can be taken out of production to save time and money and create conservation habitat in the agricultural ecosystem. We quantify the effects of heterogeneity to determine if it provides benefits to farmers such as enhanced biodiversity, ecosystem functions and farm productivity in agroecosystems.

Project Objectives:

My goal is to quantify the agronomic, economic and biodiversity impacts of midfield islets (refugia) in dryland small grain production region of the Northern Great Plain (NGP). Specifically, I will quantify the effects of habitat heterogeneity on yield and biodiversity in production fields.

  1. Quantify what costs and benefits midfield islets bring to farm production. We aim to determine if midfield islets affect agricultural production by looking for significant differences in crop yield and crop quality between homogeneous and heterogeneous fields and landscapes.
  2. Determine the tradeoff between ecosystem services and disservices that midfield islets create for producers. We aim to determine if midfield islets affect ecosystem resilience by looking for significant differences in pollinator, parasitoid, bird and small mammal populations, plant species richness, and pest and weed predation between homogeneous and heterogeneous fields.
  3. Share findings of on-farm experimentation through farmer-to-farmer networks, evaluate producers’ attitudes towards biodiverse farming methods and identify barriers to producer adoption.


Click linked name(s) to expand
  • Gary Broyles - Producer (Researcher)
  • Casey Bailey - Producer (Researcher)
  • Ole Norgaard - Producer (Researcher)


Materials and methods:

In this study, we examine the potential for wildlife habitat conservation within agricultural systems, specifically evaluating the potential for uncropped patches (midfield islets) to serve as refugia for biodiversity in production fields. We will evaluate heterogeneity at the field and landscape level using an index of vegetative heterogeneity (cover type) and landscape heterogeneity (midfield islets) to determine its impact on biodiversity (including insects, plants and small mammals) and associated agroecosystem services. Three fields with and three without midfield islets were selected from 3 farms in different regions of Montana to compare yield and biodiversity data between homogeneous (fields without midfield islets) and heterogeneous fields (fields with midfield islets). Fahrig’s definition of functional landscape heterogeneity will be used to identify functional cover types that are based on the resource dependencies of species rather than physical habitat characteristics. Functional cover types will be designated across all 6 fields to compare how yield and biodiversity vary with habitat spatial heterogeneity. In addition, the mean regional crop diversity within 10 km (over the past 4 years) of the center of each field will be accessed using USDA CropScape (USDA, 2015). Within field heterogeneity will be estimated using a vegetative cover type index and within field biodiversity will be evaluated with insect, bird and small mammal surveys. We will use these survey results to model patterns of biodiversity distribution across vegetative cover types and test the hypothesis that heterogeneity in vegetation structure provides a greater variety of habitat for wildlife.


Methods for Objective 1: Precision agriculture technology (combine harvester mounted yield monitors and grain protein analyzers) will be used to create yield maps and identify low-yield and high-input areas in each field. These will be converted to profit maps that quantify the costs and benefits of converting low-producing areas to refugia (e.g. wildlife habitat). The same maps will be used to highlight any effects of habitat spatial heterogeneity on crop yield and quality by mapping yield and protein content in relation to the spatial configuration (distance to, size, etc.) of midfield islets. Spatial differences in yield and nutrient concentration will determine if midfield islets offer costs or benefits to producers by determining if crop yield and quality vary significantly between homogeneous and heterogeneous fields as a function of distance to edge or islet and degree of landscape fragmentation and using and augmenting methods previously described. We will complete profit maps using yield data from 2020.


Methods for Objective 2: Insect, plant and small mammal surveys will be used to compare ecosystem services associated with agrobiodiversity across field types. Six 100 meter transects were established in a radial design from the center of each refugia and extended out to the cropped area for each type of survey. Sweep nets were used to trap and identify pollinators and parasitoids (bees, butterflies, wasps, etc.) along each transect in 20 meter segments, with a total of 100 sweeps per transect. One sweep was considered as one step taken as the net is swept in a 180 degree arc as low as possible to the ground. All collected insect specimens were frozen and will be identified in the winter of 2020. The number of total individuals captured will be identified to the family level in order to compare winged insect diversity between the two types of fields. 

Vegetation monitoring plots were to compare plant species richness and diversity between homogenous and heterogeneous fields and as a function of distance from refugia within heterogeneous fields. The occurrence of all present grasses, forbs and shrubs were recorded at 10 m intervals along the pre-established transects in quarter meter squared frames, with a total of 60 sample frames per field. Species richness will be defined as the total number of species encountered in a field. Plant species diversity was evaluated with Shannon’s Diversity Index as a function of distance from the refugia center.

Small mammals will be captured in late August of 2020 and uniquely marked with ear tags for mark-and-recapture analyses, allowing abundance and diversity assessments for small mammals. Five Sherman live traps will be placed in each field at 10-m intervals along the transects, for a total of 30 live traps. Each captured animal will be uniquely marked with serially numbered ear tags or by toe-clipping for species that cannot be ear-tagged. The species, sex, age, reproductive condition, and weight of captured animals will be recorded. Fluorescent powder pigments will be used to monitor small mammal resource and habitat use to determine the effects of seed predation on the weed seed bank and wheat grain production. All small mammal trapping and handling procedures will follow guidelines approved by the American Society of Mammalogists and the Montana State University Institutional Animal Care and Use Committee. Small mammal abundances will be calculated using mark–recapture statistical analysis implemented in R using the package RCapture. 

Significant differences in winged insect, plant and small mammal diversity between homogeneous and heterogeneous fields will be used to assess the role of midfield islets in providing accompanying ecosystem services such as pollination, pest-control, wildlife habitat and plant diversity to producers.


Objective 3: Producer Adoption

Due to complications surrounding COVID-19, surveys of PARA producers’ willingness to adopt wildlife friendly farming techniques will be prepared and conducted over the internet during fall 2020. Post surveys of producer willingness to adopt wildlife friendly farming techniques will be conducted in spring 2021. Amoeba diagrams of producer perceptions of on-farm biodiversity and ecosystem services will be prepared and completed in spring 2021 and 2022. Results will be shared and discussed during the annual PARA meeting November 2020 and 2021.

Research results and discussion:

These are preliminary results that will be further analyzed in 2020.

First, we found that fields with refugia in them had higher plant species richness and diversity than fields without refugia in two of three farms.

Bailey Farm:

Norgaard Farm:

*note that diversity was actually higher in the control than in the refugia because Norgaard’s refugia was a bare patch of alkaline land that is in the process of being restored

Broyles Farm:

Second, we found that plant species richness declined with distance from refugia in all three farms and plant diversity decreased with distance from refugia in two of three farms.


                                          p-value = 0.0131                                       p-value = 0.0064                                      p-value = 0.0107

*note that diversity increased with distance from refugia on Norgaard’s farm and we plan to observe how this trend might change as the refugia continues to be restored and enhanced

Next, in the fall of 2020 we will analyze how insect and small mammal diversity relate to plant diversity in a spatially explicit manner.

Last, we will analyze how plant, insect and small mammal diversity relate to crop yield and crop quality after harvest in fall 2020.

Participation Summary
3 Farmers participating in research

Educational & Outreach Activities

3 Consultations
1 Tours
1 Webinars / talks / presentations
6 Workshop field days

Participation Summary

5 Farmers
2 Ag professionals participated
Education/outreach description:

Our agroecology lab at MSU has been conducting on-farm precision experimentation (OFPE) with producers from the Precision Agricultural Research Association (PARA) of Montana since 2015. PARA functions as a Participatory Research Network for farmer-to-farmer education. We visit each producer multiple times throughout the year to tour, consult and conduct fieldwork on their farms. The three producers in this project (Gary Broyles, Ole Norgaard and Casey Bailey) will share this year’s results with the other 42 producers in PARA and train fellow members to utilize technologies and generate tailored data for their own farms at the annual PARA meeting in November. We will also present a workshop to equip Montana farmers with the tools for profit mapping their own individual fields and calculating the costs and benefits of taking certain areas out of production.   

Project Outcomes

2 Farmers changed or adopted a practice
1 Farmers intend/plan to change their practice(s)
1 Grant received that built upon this project
Did this project contribute to a larger project?:
1 New working collaboration
Project outcomes:

This project offers an incentive to maintain uncropped, biodiverse areas within farmer’s fields as refugia. We hope to show that refugia may not only result in the saved cost of seed, but offer non-monetary profits due to enhanced insect, plant and small mammal diversity. Refugia also contribute to higher quality of life for producers. Some have already commented on the enjoyment they receive from seeing wild animals and wild flowers on their property. 


Experimenting with farmland heterogeneity is especially pertinent to producers, since multifunction agricultural biodiversity has been identified as an important future research theme in sustainable agriculture and global food supply. This study aims to clarify the effects of habitat heterogeneity in agricultural ecosystems by quantifying yield and biodiversity responses. In regard to yield, farmers can profit from the use of precision agriculture and precision conservation technology to identify optimal crop areas, optimize nutrient inputs, and avoid economic loss. Farmers may also experience pest control benefits from on-farm biodiversity. Insects are estimated at saving producers approximately $4.5 billion/y in avoided crop damage in the United States alone. Furthermore, managing for heterogeneity increases pollinator populations, which have been shown to improve production of 70% of the most important crop species worldwide and influence 35% of global human food supply. Producers may also benefit from on-farm vegetative diversity, which has been shown to reduce soil and nutrient loss by more than 90% in a diversified corn-soybean system. Increased mammal diversity may also provide beneficial weed seed predation services. While habitat heterogeneity has been proven to provide financial and ecological benefits to producers, there are also possibilities when habitat conservation in farmland may reduce crop production by enhancing pests. This study aims to examine both the monetary costs and benefits as well as ecosystem services and disservices that accompany heterogeneity in agricultural systems in order to provide a management tool for producers that optimizes crop production and habitat creation in farmland

Knowledge Gained:

We continue to learn from our producers throughout the collaborative research process. This year we saw how On Farm Precision Experimentation can discourage producers by creating short term costs from “controls” or “0s”. We are learning how to better design on-field experiments so they can minimize those costs for our producers while hopefully obtaining the data we need to maximize long term benefits. For example, two producers have agreed to plant a diverse cover crop mix or pollinator strips to benefit the pollinator communities on their farms. Though this is not the cheapest choice for producers, it may have positive outcomes for overall farm diversity and future yield.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.