Dynamics of Dung Invertebrate Communities, and Their Contributions to Profitability in RegenerativeRrangelands

Progress report for LNC18-410

Project Type: Research and Education
Funds awarded in 2018: $200,000.00
Projected End Date: 05/01/2021
Grant Recipient: Ecdysis Foundation
Region: North Central
State: South Dakota
Project Coordinator:
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Project Information

Summary:

 

Regenerative rangeland management employs practices that improve soil health and conserves biodiversity while producing nutrient dense food profitably. Dung insects are important in rangeland function, but the effects of herd and rangeland management on their services and economic contributions to the ranch remain poorly understood. Our goal is to characterize the effects of regeneratively and continuously grazed rangelands on dung invertebrate diversity and dung degradation rates, explore how plant diversity influences these dynamics, and assign an economic value of these services under different management scenarios in North and South Dakota. A character matrix based on producer interviews will be used to categorize ranches as regenerative and conventional based on their management practices. Dung insects will be collected from soil cores through pats, and plant communities will be described from transects and quadrat samples. Dung degradation rates and fecal associated parasites will be determined under different rangeland management scenarios. Economic models will be developed that calculate the cost benefits of dung degradation based on pasture fouling, nutrient incorporation, and pest reduction to value dung degradation services under the two management systems. Ranchers are a crucial participants in this project in several capacities. Rancher interest is what prompted the creation of the project, participating ranchers will define the best management practices of the two systems based on their operation, will maintain the experimental sites, and will be instruments to disseminate the results to their communities. Outreach is a major priority for the work, and field days, presentations at stakeholder meetings, dissemination through extension and stakeholder groups, and social and traditional media are all venues to ensure that our research will reach a wide target audience. The results of these experiments will provide ranchers with an understanding of how invertebrate diversity contributes to the profitability of regenerative and conventional rangelands, and provide ranchers with tools to assess the effectiveness of their management method, ultimately increasing the adoption of regenerative grazing and other biodiversity conservation management methods.

Project Objectives:
  1. Describe the effect of regenerative grazing on invertebrate diversity in cattle dung.
  2. Estimate dung degradation rates and fecal parasite removal contributed by dung invertebrate communities.
  3. Determine how plant community characteristics affect dung insect diversity.
  4. Estimate the economic contributions of dung degradation to rancher profitability.

Learning outcomes:

Development of a better understanding of how cattle management affects dung invertebrate services, as well as how these services are related to plant diversification on ranches.

Action outcomes:

The major action outcome will be economic justification of dung invertebrate conservation under different cattle management scenarios.

Introduction:

Background. Regenerative rangeland management has the potential to mitigate national concerns (e.g., carbon sequestration, soil health and biodiversity conservation), while simultaneously increasing the resilience and profitability of ranchers. A cornerstone of regenerative management is Adaptive Multi-Paddock (AMP) grazing, which is based on improving economic returns to restore ecosystem functions by avoiding localized overstocking and overgrazing. This is accomplished primarily by adjusting stock numbers as needed to ensure adequate herbaceous vegetation to provide for the needs of the livestock and to keep basic ecological functions operational. It avoids overgrazing by using multiple paddocks per herd with short grazing periods and long recovery periods, and adaptively changes animal numbers, recovery periods and other management elements as climatic conditions change. Ranchers around the world are successfully applying regenerative management to increase the biophysical and economic resilience of their operations, while scientific debate ensues whether the claims made by regenerative proponents are valid (Briske et al., 2011; Heady, 1961; Teague et al., 2013). Evaluating and verifying the environmental and socio-economic benefits of regenerative management strategies on key ecosystem services in the North Central Region will be crucial in altering the behavior of ranchers.

Invertebrates are the most diverse group of animals on Earth (Basset et al., 2012), and this source of biodiversity contributes to carbon sequestration, grassland productivity, and rancher profitability. The economic value of the services of dung invertebrates for the US beef industry has been estimated at $469 million annually (adjusted to 2018 $), due mainly to reduced forage fouling by dung, reduced parasite loads and suppression of pest fly populations via ecological competition and direct consumption (Losey & Vaughan, 2006).  Additionally, dung-processing by beetles can improve nutrient cycling in the soil, and improve the growth and nitrogen content of vegetation (Bang et al., 2005; Nichols et al., 2008). However, dung invertebrate communities in important beef-growing states in the northern Great Plains area are poorly known, and there remain many gaps in our current knowledge about how dung-removal services are influenced by the behavior and ecology of the beetles, as well as by rangeland management practices.

Rationale. Cursory economic analyses strongly suggest that dung beetles contribute substantially to the economics of cattle production; however, these valuations would benefit from using modern numbers and an experienced team to generate current values for services of dung invertebrate communities as a whole. As one component of the biodiversity within a habitat, dung invertebrates provide services in at least three areas: a) a reduction in pasture fouling due to cattle dung, b) sequestration of dung trapped nitrogen recycling, and c) and a reduction of pest population levels for pests that rely on dung as habitat. We argue that dung invertebrates also would alter plant communities within pasture systems by affecting soil properties. Problems associated with public estimates of these services are several fold. First, dung invertebrate contributions to the degradation rates of dung are poorly quantified (Fincher 1981; Floate et al. 2005); a factor that we have overcome in a previous NC-SARE funded proposal. Current estimates used in models suggest that dung requires approximately a year to be incorporated into the soil (Beynon et al. 2012a, Kaartinen et al. 2013); our surveys suggest that most organic matter in dung can be incorporated into soil of the Dakotas in as little as a few days (J. G. L., unpublished data based on Pecenka’s grad student fellowship). Next, existing economic models do not account for the life cycle of the dung-associated pests, and especially the duration of the infective period for these parasites. For example, dung must be removed within a short window of time or parasites can reinfest/complete their life cycles, and this needs to be accounted for when calculating the effects of dung removal on parasite numbers. Finally, historical numbers associated with cattle stocking rates (and associated dung production levels per area of pasture) and values for things like N sequestration and beef prices may not be relevant in today’s markets, particularly with reference to regenerative management operations.

Need. Our interest in dung insect communities stemmed from the groundswell of interest from area producers. Dr. Lundgren has 5,000+ face-to-face contacts with producers annually, and a high number of questions he receives pertains to how to get “dung beetles” into their ranches. Our team has gathered informal survey data over the past five years from North Central Region beef producers at field days, workshops, and tours regarding the interest level in dung invertebrates. Producers would like to see more dung beetle activity on their ranches, find out what the different species are, and what they can do to increase their populations. This is evident by our support letter from the South Dakota Grassland Coalition and Grassfed Exchange, and individual support letters from ranchers wishing to participate in this research project. Dung beetle conservation has also been identified as an interest area by NGOs like Nature Conservancy, WWF, and NWF. Aside from adjusting stocking densities, current and historical projects offer few options for what ranchers can do to amend their pastures to encourage endemic dung beetle communities to increase dung removal rates. Our goal is not only to document the multi-faceted and complex effects of dung insects on the economics of cattle production, but also to explore ways that ranchers can manipulate their pasture systems (including stocking densities) to promote these ecosystem services on their operations.

NC-SARE has recently funded only two dung-insect related proposals, which our team used as a springboard to generate the current proposal. A farmer-rancher project (FNC14-977) investigated how dung pat degradation reduced fly populations, and a graduate student fellowship (GNC15-207) explored how dung insect diversity affects dung degradation. This work revealed that maggot populations were lower on regenerative ranches than on ivermectin-treated, continuously grazed ranches. We have characterized the dung insect community in the Northern Plains, identifying 200,000 insects representing 175 species. Dung beetles comprised only 3% of this community, but acted as keystone species that opened the dung resource for other insects to colonize. The next step in this body of work is to determine how cattle and pasture management affects dung removal rates, and to put a clear economic value to this service to help transfer the technology to the ranching community.

Rancher involvement. This project was fundamentally driven and supported by the ranchers of the North Central Region. Regenerative ranchers are ahead of the science in terms of biodiversity conservation in their operations, including dung insect conservation. With this in mind, the ranchers have defined our treatment structure through the practices on their farms. We will also rely on ranchers in the region to identify neighbors that are ranching conventionally. Ranchers will also provide us with information about their operations that we will use in our socioeconomic analysis. Getting this type of information from ranchers is sometimes challenging, and we have specifically allocated personnel and resources to developing relationships and trust with these ranchers to attain our desired outcomes. Finally, ranchers will be an important mouthpiece for disseminating the results of the research we obtain. Field days at participating ranches will help to illustrate the research outcomes, and stories provided by ranchers will be used to encourage behavior changes in others withing the north central ranching community and beyond. Thus, ranchers will be intimately involved in many aspects of the study design, interpretation of the results, and dissemination of the results from this groundbreaking project.

Limitations of the project and their solutions. Based on our previous experience in this system, we have carefully considered several aspects of the system to ensure success and maximizing the impacts of our work. On the insect community description, sampling intensity may be adjusted depending on trap capture rates and rarefaction analysis to ensure that we are collecting the majority of this community. We recognize that this process may ignore some of the dung invertebrates that dwell outside of the pat (e.g., rolling dung beetles); there is no one perfect sampling procedure, and the results will have to be interpreted accordingly.

For the economic analysis, the time distributions will be adjusted based on the speed at which dung is removed in the pastures. Based on preliminary trials and temperature conditions, we will determine how long the fecal parasites remain at infective life stages under current conditions and adjust the second fecal parasite collection accordingly. Finally, we will increase the number of pats sampled if the quantity of fecal material varies substantially within a pasture. We may calculate Dv empirically, if values presented in the literature seem unsatisfactory.

We debated including a soil scientist on this work that could more completely describe the soil nutrient status resulting from regenerative rangeland management, with particular consideration of dung invertebrate and plant communities. Regrettably, the budgets didn’t allow for including another discipline while conducting the level of detail needed for the dung invertebrate and economic analyses. To overcome this shortcoming of the proposal, we have full nutrient analyses budgeted for the soils that will be conducted at Ward Laboratories under contract. Also, the results of this project will be dovetailed with ongoing examinations by other research teams, notably the Soil Carbon Cowboys team which will quantify soil health and carbon sequestration on AMP ranches in the Northern Plains in 2018; this group will not be able to conduct invertebrate sampling without extramural funds.

 

Bibliography.

Bang, et al. (2005) Effects of paracoprid dung beetles (Coleoptera: Scarabaeidae) on the growth of pasture herbage and on the underlying soil. Applied Soil Ecology, 29, 165-171.

Basset, Y., Cizek, L., Cuénoud, P., et al (2012) Arthropod diversity in a tropical forest. Science, 338, 1481.

Briske et al (2011) Origin, persistence and resolution of the rotational grazing debate: Integrating human dimensions into rangeland research. Rangeland Ecology and Management, 64, 325-334.

Egwang & Slocombe (1982) Evaluation of the Cornell-Wisconsin centrifugal flotation technique for recovering tichostrongylid eggs from bovine feces. Canadian Journal of Comparative Medicine, 46, 133-137.

Losey & Vaughan (2006) The economic value of ecological services provided by insects. Bioscience, 56, 311-323.

Nichols et al (2008) Ecological functions and ecosystem services provided by Scarabaeinae dung beetles. Biological Conservation, 141, 1461-1474.

Teague, et al (2013) Multi-paddock grazing on rangelands: Why the perceptual dichotomy between research results and rancher experience? Journal of Environmental Management, 128, 699-717.

Cooperators

Click linked name(s) to expand
  • Dr. Jonathan Lundgren (Educator and Researcher)
  • Dr. Ryan Schmid (Educator and Researcher)
  • Dr. Urs Kreuter (Educator and Researcher)

Research

Hypothesis:

Research objectives are:

  1. Describe the effect of regenerative grazing on invertebrate diversity in cattle dung.
  2. Estimate dung degradation rates and fecal parasite removal contributed by dung invertebrate communities.
  3. Determine how plant community characteristics affect dung insect diversity.
  4. Estimate the economic contributions of dung degradation to rancher profitability.

Learning outcomes:

Development of a better understanding of how cattle management affects dung invertebrate services, as well as how these services are related to plant diversification on ranches.

Action outcomes:

The major action outcome will be economic justification of dung invertebrate conservation under different cattle management scenarios.

Materials and methods:

Grazing treatments consisted of rancher-defined best management practices for regenerative and a conventional alternative management scheme, typically represented by a continuous grazing plan. Selected sites (n = 5 per grazing treatment per year for 2 years) focused on rangelands in the Dakotas. A central challenge with in situ systems research is empirically distinguishing the systems, which are each unified in their goals/philosophies, but vary in particular practices. Therefore, grazing treatments were paired in each region, and treatments were assigned based on a character matrix. This matrix consisted of a range of production practices that are regarded as regenerative or conventional, and each ranch will be scored by the number. Each management system was in place for at least 5 years, and ranches were >100 acres.

On each ranch, dung density was assessed on hillside catenas along 50 m transects. To determine fecal pat density, the number and area of the fecal pats was measured. Fecal pat density was assessed three times over the season; once in the spring, summer, and early fall. Fresh dung pats (<4 h old) were identified on catenas. Intensive sampling of vegetation then occurred on the ridge and midslope of each catena.

In-depth interviews were conducted with each of the 20 ranches selected for the project. These interviews required more than one day per ranch including travel between ranches. The purpose of these face-to-face interviews was to characterize each ranch operation in detail with respect to long-term land management goals, management decision making, livestock production goals and practices, and ranch economics. Additionally each operation was characterized with respect to decisions to move cattle between paddocks during the year and change in number of animals on the property during each year factors influencing timing of livestock sales, as well as supplemental feed and mineral purchases, parasite control and veterinary treatments. Information about variable input costs being sought include labor, fuel, supplemental feed, mineral supplements, parasite treatment, and other veterinary costs. Fixed costs information includes fencing costs for current grazing paddock configuration, moveable fencing costs, and livestock watering and handling facilities. Production-related aspects of each ranching operation will be characterized for the three most recent years.

 

Objective 1: Dung invertebrate communities

 Invertebrate communities were collected in June, July, and August at each site. Individual 50 m transects were established on the ridge and midslope of each catena. Along each of these transects, five pats < 2 d old were sampled. Previous work by our team has determined that the richest community resides in pats of this age. A core (10 cm diam, 10 cm deep) of soil and dung were collected from each of these pats. All invertebrates were enumerated and identified to as low a taxonomic position as possible. Functional guilds (e.g., coprophages, predators, pests, herbivores, etc.) were applied to each operational taxonomic unit (OTU; i.e., morphospecies). Species diversity metrics (Species richness, Shannon Index, Simpson Index, Evenness, etc.) were determined for each ranch. Community indices will be compared between regenerative and conventional ranches using ANOVA or non-parametric equivalent (as appropriate).

A 10 g subsample from each pat was examined for fecal parasites Egwang & Slocombe, 1982. Helminth eggs and larvae are phenotypically identified as trichostrongyle-type, Nematodirus-type, Trichuris-type and Moniezia-type, and expressed as parasites/g. The helminth parasites per g of dung will be compared between the two treatments; the relationship of helminth abundance and dung weight and OM quantity over time will be determined.

 

Objective 2: Dung degradation

Dung degradation rates were measured twice over the season (as opposed to three times for insect and plant communities in Obj 1 & 3), in June and August. Fresh dung pats (<1 d old) were collected from a ranch that did not administer pesticides. Pats were frozen (<20° C) for 72 h to kill dung dwelling arthropods before dung was formed into 1000 g pats. Pats, n = 12, were then placed onto pastures. Each pat was randomly assigned to a collection time. These times were T = 1, 2, 4, 7, 14, and 28 d. At the designated time, the fecal pat was scraped into a plastic bag and dried to constant weight (nearest g). The weight of pats was recorded. The rate of loss of total dung biomass and organic matter in the two ranch treatments will be compared.

 

Objective 3: Vegetation communities

Plant communities and biomass were sampled during three periods of the season; June, July, and August. At each of the two locations per ranch (ridge and midslope on catenas), two random 50 m linear transects were established at least 10 m apart. Visual proportion estimates of species adjacent to transect every 5 m were recorded and used to assess vegetation diversity. Visual estimates of plant cover (using the Canapeo smartphone app that quantifies green area per unit area) and litter cover was recorded in quadrats (0.25 m2, n = 4 per transect). The effects of rangeland management systems on plant community characteristics will be compared using ANOVA. Regression analyses will be used to determine how plant diversity and cover correlate with key insect community characteristics, as well as dung degradation rates on the midslope and ridge of each catena.

 

Objective 4: Economic contributions of dung invertebrates

Our approach for estimating the loss reduction is based on the decline in manure levels due to invertebrate activity. Economic valuation will be based on the reduction in: a) pasture fouling due to manure, b) decline in parasite levels, and c) nitrogen recycling based on current market prices.

We calculate the cost savings in reducing forage fouling as

Vrf = L × A × (Dnb – Db)

Where Vrf is the value of forage lost due to dung deposition, L is the economic value of the pasture land, A is the area occupied by the fecal pats (determined during the site selection process), Dnb is the duration the fecal pat remains in the absence of insects, and Db is the duration the fecal pat remains in the presence of insects (Dnb and Db were determined previously by our research team).

We will calculate the cost savings in increased N (nitrogen) reincorporation as

Vn = Fn × Fw × N% × RN × (Dnb – Db) × N$

Where Vn is the value of N reincorporation by dung invertebrates, Fn is the number of fecal pats per unit area (determined during the site selection process), Fw is the average weight of fecal pats (determined during the site selection process), N% is the proportion of fecal pats that is N (2-5%is expected, but we will also take a crude measurement of this in Obj 2), RN is the rate at which NH3 dissipates from the fecal pats (Sommer and Hutchins 2001, and references therein), and N$ is the current value of N (approximately $900 per ton in 2018; http://www.neo.ne.gov/statshtml/181.htm ).

Finally we will calculate the cost savings in parasite reductions as

If Dv < Db, then Vp = 0

If Dv > Dnb, then Vp = Fw × (Dnb – Db) × P# × P$

If Dnb > Dv > Db, then Vp = Fw × (Dv – Db) × P# × P$

Where Vp is the value of dung invertebrate derived reductions in parasites, Dv is the duration that the dung pats are viable hosts for flies (West 1951) or when 3rd instar gastrointestinal nematodes leave the pat (Stromberg 1997; O’Connor et al 2006), P# is the number of parasites per dung weight (determined in Obj 2 for fecal parasites, maggots, and adult flies), and P$ is the economic cost per parasite (Epperson et al. 2001; Mertz et al. 2005). Because of differences in many of these parameters for flies and gastrointestinal nematodes, we will calculate separate Vp metrics for each pest class. The economic cost per parasite will depend on current beef prices and weight loss caused by infection.

The total annual value of dung invertebrates is therefore calculated as

Vdung invertebrates = Vrf + VN + Vp

We recognize that economic value of beef, N, and pastureland are dependent on current markets, and that N volatilization, duration of infective parasite stages and their effects on animal weight gain, and pat removal rates all are dependent on local conditions and thus are not well-represented by a discrete number/value. To accommodate this potential variability in costs and benefits, we will generate high, low, and current average estimates for these parameters. The model to calculate VN and Vp may gain complexity if we decide to include Dnb and Db as relative rates of change, rather than the discrete duration until removal. These approaches will allow us to provide a more dynamic set of values for dung beetle services under a range of realistic scenarios.

Research results and discussion:

AS OF MARCH 5, 2020

 

Objective 1: Dung invertebrate communities

A total of 600 dung samples were collected from 20 ranches in June, July and August this year. Thousands of invertebrates have been sorted from dung, and are currently being identified to examine community structure for diversity, beneficial dung beetles, and pests.

Objective 2: Dung degradation

Degradation of dung at 10 ranches was measured in June and August this year. Results have been recorded and are ready for analysis.

Objective 3: Vegetation communities

Vegetation was sampled at 20 ranches in June, July, and August this year. Results have been recorded and are ready for analysis.

Objective 4: Economic contributions of dung invertebrates

Initial meetings were held with ranchers to build relationships and trust between ranchers and economic researchers. After meeting with ranchers, surveys were developed based upon ranchers’ insights and concerns toward gathering economic data. We expect to gather economic data from ranchers March 2020.

Participation Summary
17 Farmers participating in research

Education

Educational approach:

We will use a multipronged approach to getting the word out to ranchers and other stakeholders of the region. Relationships are key to successfully changing behavior, and face-to-face contacts are crucial in establishing trust and credibility from our target audience. Seeing is believing, and two annual field days are included in the project to bring ranchers to the field sites and explain the results of our project. Showing ranchers how to collect and identify dung invertebrate communities, and pointing out how these insects interact with plant communities to provide services to ranchers. Another key point of these events will be to show how conventional and regenerative rangeland management differ in their plant and invertebrate communities, as well as pat density and quality. We will advertise these events widely in the Farm Forum, Tri-state Neighbor, Agweek, and local and regional news outlets, as well as doing press releases on social media outlets and SDPB, NDPB, and MPR. We expect a minimum of 75 attendees at each event (note that our annual field event at Blue Dasher Farm attracts 150+ attendees, but we wanted to be conservative in our field day projections). In addition to these events, members of our team regularly speak at regional, national, and international conferences, and the research produced by this project will be shared directly with producers at these meetings (J.G.L. has 5,000+ face-to-face contacts with producers annually).

We will extend the reach of our project using a variety of media. Face-to-face contacts have a high impact with participants, but it is difficult to reach a broad audience with this approach. Additionally, ranchers learn in different styles, and this necessitates using a variety of teaching tools. We will produce a series of Youtube videos and podcasts based on our field day content that helps to disseminate our project results to a broader audience. Furthermore, we will employ social media tools Facebook and Twitter to disseminate key research outcomes from the project. SDSU and NDSU extension, as well as Grassland Coalitions, the Grassfed Exchange, SD Soil Health Coalition, and Northern Plains Sustainable Ag Society will all be clearing houses for this information to reach their wide and diverse memberships. Members of our team have an extensive media network, and we will provide press releases and interviews on this cutting edge project that will extend the reach of our outreach program even further.

Project Activities

Blue Dasher Farm Field Day

Educational & Outreach Activities

1 Workshop field days

Participation Summary:

100 Farmers
1 Ag professionals participated
Education/outreach description:

Blue Dasher Field Day

Learning Outcomes

17 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
17 Agricultural service providers reported changes in knowledge, skills, and/or attitudes as a result of their participation
Key areas taught:
  • Regenerative Rangeland Management

Project Outcomes

Key practices changed:
  • How they are managing their cattle herds

1 Grant applied for that built upon this project
20 New working collaborations
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.