Tree Regeneration and Establishment Strategies in Silvopasture and Sugarbush Systems

Final report for FNE19-939

Project Type: Farmer
Funds awarded in 2019: $13,450.00
Projected End Date: 11/30/2021
Grant Recipient: Hidden Blossom Farm
Region: Northeast
State: Connecticut
Project Leader:
Dr. Joseph Orefice
Hidden Blossom Farm
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Project Information

Summary:

Tree establishment is one of the primary challenges farmers face when adopting agroforestry techniques. More specifically, a major critique of silvopasture, by non-silvopasture practitioners, is that regeneration is overly challenging in the face of livestock damage and deer browse. This study had three primary objectives: 1) to determine the effectiveness of different apical bud protection methods during the establishment phase of silvopasture from treeless pasture and during enrichment planting of a sugarbush 2) to determine the tradeoffs between organic, chemical, and mechanical control of grass when establishing silvopasture from treeless pasture 3) to establish an on-farm demonstration area in New England of silvopasture regeneration techniques. We compared the use of no bud protection, paper bud caps, woody shrubs, and tree tubes in the protection of hardwood tree seedlings from deer in silvopasture and sugarbush applications to accomplish the first objective. To accomplish the second objective we compared the effects of white clover living mulch, glyphosate, composted hay mulch, and grass clippings on height growth of fruit trees planted in silvopasture establishment from treeless pasture. We found tree tubes provided the best protection from deer but did not allow trees to grow taller than the tube. Shrubs provided protection for half of the trees and competition for the other half. Bud caps and the no protection control did not work because deer browsed trees year round. For the mulching portion of the study: mulch of waste hay trended toward the best form of protection for fruit trees from grass competition. Mortality of fruit trees due to deer browse and antler rubbing was a major concern while damage due to livestock was minimal because electric fencing was used to keep cattle off of fruit trees and cattle were rotated. Fruit trees were expensive to establish at over $65 per tree with all costs considered. 65 farmers participated in this study along with 33 agricultural service providers, through the two farm tours and webinar we held as part of this project. 

Project Objectives:

This project seeks to address the following three objectives:

1) To determine the effectiveness of different apical bud protection methods during the establishment phase of silvopasture from treeless pasture and during enrichment planting of a sugarbush. The impact of this objective will be to better inform farmers about the effectiveness of bud caps, no bud protection, tree tubes, and the use of shrubs to protect trees from deer and livestock during silvopasture regeneration and enrichment planting of a sugarbush.

2) To determine the tradeoffs between organic, chemical, and mechanical control of grass when establishing silvopasture from treeless pasture. This objective will inform farmers of the tradeoffs between four methods of minimizing grass competition with trees: clover as a living mulch, clipping of grass, glyphosate, and manure/waste hay as a mulch.

3) To establish an on-farm demonstration area in New England of silvopasture and sugarbush regeneration techniques. The impact of this objective will be to provide farmers with information and a go-to location for learning about how to regenerate and establish silvopastures on their farm and how to enrich poorly managed sugarbushes with valuable species.

Introduction:

Silvopasture has received significant interest in the Northeastern United States over the past decade. Farmers in the region are recognizing that woodland on their farm may serve a grazing purpose in addition to growing trees. My past research on North Branch Farm, funded through the SARE program, had documented the benefits and tradeoffs of converting forest to silvopasture (Orefice et al 2017a, Orefice et al in-press). One result of this work showed that silvopasture, when compared to treeless pasture, holds many soil and livestock benefits. However, much of the focus of silvopasture in our region has been on forest conversion while little work has been conducted on converting treeless pasture to silvopasture. Establishing trees in pasture is arguably the most environmentally friendly method of creating silvopasture and is likely to provide the most ecosystem services in terms of water quality and soil health. My past work in New York and New England found that lack of knowledge toward management of silvopasture systems and toward tree care were major inhibitors to silvopasture adoption (Orefice et al 2017b).

Description of farm operation:

I have been independently farming for nine years. The first eight of those years were on North Branch Farm in Saranac, NY. On that farm I practiced and conducted research on silvopasture and also grew vegetables and fruit. The farm served as a demonstration area for silvopasture and I hosted over 30 tours and multiple classes during the course of my time there. I hold a Ph.D. in silvopasture from the University of New Hampshire, was an Associate Professor of Forestry at Paul Smith’s College, and served as Director of Cornell University’s Uihlein Sugar Maple Research Forest and Northern New York Maple Specialist.
In 2018 I accepted a position with Yale University as Director of Forest & Agricultural Operations and Lecturer in Agroforestry. I have since sold North Branch Farm and have moved my farm business to 134 acres of land I purchased in Union, Connecticut, called Hidden Blossom Farm. I am currently raising and rebuilding my herd of 11 beef cattle there and developing new silvopasture systems both from open pasture and forested land. The farm also has a degraded sugarbush that I am working to get back into production over the long-term. Like much of the Northeast, the sugarbush has an understory of invasive shrubs from unmanaged woodland grazing and a lack of regeneration due to deer browse. My farm is well set up to meet all the mechanical and infrastructure needs of this project.

Cooperators

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  • Dr. Peter Smallidge - Technical Advisor (Researcher)

Research

Materials and methods:

Part one of this study is a randomized complete block design to investigate strategies for apical bud protection from deer for trees planted in silvopasture and sugarbush systems. Six blocks were established, two in a shrubby grazed area being converted to silvopasture through planting and four in a formerly high-graded sugarbush with an understory of Japanese barberry and multiflora rose. The main factor of the randomized complete block design is an apical bud protection strategies of planted trees (Figure 1). This factor consists of four treatment groups: 1) control, no apical bud protection 2) paper bud caps in all blocks with additional polywire protection during the grazing season in silvopasture blocks (post-it notes stapled around the terminal bud during the dormant season) 3) planted in the center of a Japanese barberry or multiflora rose cluster 4) and 5’ tall tree tubes in all blocks with additional polywire protection during the grazing season in silvopasture blocks. Each treatment is of 10 trees, totaling 40 trees per block. Walnuts and hybrid chestnuts were established in the silvopasture blocks and oaks, walnuts, and sugar maples were established in the sugarbush areas.

All trees were tagged and initial height measurements were collected when they were planted in the spring of 2019. Tree height, browse damage, and mortality will be recorded in the spring of 2020 and 2021 and compared to initial measurements. Statistical analysis will be conducted for the study in 2021 to determine the effectiveness of treatments.

Part two of this study is to assess the value of living mulch when converting treeless pasture to silvopasture. We used a randomized complete block for this design. Five complete blocks were established in areas that are currently in treeless pasture. Fruit trees were planted in four, 5 tree rows within each block at a 20 foot by 20 foot spacing (Figure 1). Apples, pears, and stone fruit were the species planted and varieties were consistent between treatment groups within a block. Each block consists of four treatment groups: 1) control, pasture grasses regularly clipped around the base of trees 2) white clover established and regularly clipped as a living mulch 3) glyphosate sprayed around the base of trees 4) waste hay and manure layered as mulch around each tree in the spring.

Trees in these systems were protected from livestock during the grazing season with the use of temporary polywire and small paddock rotational grazing. Please note that Joseph Orefice has had excellent success with this method of tree protection in the silvopastures on his former farm, North Branch Farm in New York. Mesh tubes were used to protect trees from deer until they are above browse height and plastic screen was placed around the base of trees to protect them from rodents.

All trees were tagged and initial height measurements were collected when they are planted in the spring of 2019. Tree height, browse damage, and mortality will be recorded in the spring of 2020 and 2021 and compared to initial measurements. Statistical analysis, on-way ANOVA, was conducted for the study in 2021 to determine the effectiveness of treatments.

Part three of this project is to document tree establishment costs and estimates of time involved for tree care during parts 1 and 2. Actual costs and labor hours involved in planting, protecting, and managing grazing around trees was documented over the course of this project. These costs were analyzed to provide farmers real numbers related to tree establishment and the time involved when converting areas to silvopasture. 

Research results and discussion:

Agroforestry Tree Regeneration tables and graphs

Part 1: Deer browse

Deer browse protection was analyzed based on tree seedling survival because height growth was highly variable and negative in some instances due to browse. See: "Survival of Tree Seedlings in 2021 Under Four Deer Browse Protection Treatments" graph. 

Tree tubes provided the greatest browse protection with 72% survival and this was significantly higher than other treatments. Brush protection followed with 50% survival, which was significantly greater than bud caps and the control (no protection). Bud caps had 28% survival and no protection had 27% survival, these were not significantly different from each other.

Based on these results I feel it is best to protect trees in some year-round manner from deer browse. While the tree tubes kept trees alive, they did not allow any trees to grow above the height of the tube (4 feet) because deer would browse as soon as the tree got above the tube. Taller tubes would have helped trees get above browse height. The shrub protection worked to deter deer browse for half of the trees while the other half died due to competition and/or deer browse. This treatment was effective but also should not be implied that invasive shrubs facilitate tree regeneration. Trees were planted in these shrubs and based on the lack of natural regeneration of trees, it is not likely that trees can establish on their own among a dense shrub layer. 

Other lessons learned from the deer browse protection portion of this study include:

  • Square stakes would have been better than round ones for holding tree tubes up in the wind and ice
  • Trees may not be establishing under invasive shrubs but some may be protected once established
  • Deer browse trees once they got above tree tubes

One unexpected turn in this project early on was that deer browse was heavy during the growing season. I made a poor assumption that deer browse would be a problem only in the winter, however we had many issues with deer browse year-round. This led to the bud-cap portion of the study not functioning as the bud caps were for winter protection of buds, and leaves/shoots were consumed during the growing season by deer. 

Part 2: Silvopasture mulching systems 

Mortality of fruit trees was low during this study, with 92% survival. Of the 8% of trees which did not make it, all but one died due to deer damage during the fall when bucks would rub their antlers. The single tree that died from other causes was due to a dog vomit slime mold which established near it's roots during the year of planting, this slime mold was living off the dying root of a large ash tree which was cut nearby.

I analyzed root collar diameter growth and height growth from spring 2019 to fall 2021 (3 growing seasons). Root collar diameter growth was statistically similar between treatments but followed a similar trend to height growth (see graphs), with waste hay mulch trending toward the greatest growth and cut grasses trending toward the lowest growth, and herbicide in the middle. 

Fruit tree height growth was 3.82 feet for waste hay mulch after 3 seasons and this was significantly greater than clipped pasture grass treatment at 2.99 feet of growth after 3 seasons. Herbicide at 3.41 feet and clover at 2.8 feet were not significantly different from each other or the other two treatments. 

Based on these results it seems that mulching trees with wasted hay and manure was the best for growth but more research would be needed to document the significance of this treatment. Regardless, having some type of mulch, herbicide, or cover crop seemed better than just cutting pasture grasses around fruit trees. Height growth is especially valuable in planted silvopastures because getting trees above deer and livestock browse height as soon as possible helps to ensure their success. 

I'll also note that tree tubes an polywire were used to protect fruit trees from cattle damage but were limited in their ability to protect trees from deer damage.

The areas had been grazed 4-5 times by cattle each season and very little damage, and no mortality, from cattle occurred. Six of 100 trees had bite marks toward the base from cattle but this damage was healing over. Cattle damage only occurred among peach and semi-dwarf apple trees. I believe this was because the spacing of peaches and semi0dwarf apples were closer together, resulting in less space for the herd of cattle between trees - leading to more negative tree-livestock interactions. In areas where standard apples were spaced at 25' between rows (instead of 15'-20') there was no damage from cattle. 

Finally, species and variety of fruit trees had many differences in height and diameter growth. This study was not designed to statistically analyze these differences, but based on data I plotted (see graphs) I feel farmers would benefit from research testing which varieties of fruit trees have the fastest growth in silvopastures. 

Part 3 (costs in this section are totals between 2019 and 2021):

Tree costs and labor 

Tree and labor costs in part 1 of this study were greatest for tree tubes and bud caps over the 3 seasons of this study with total costs per tree of just over $5 for most treatment and $7.85 for tree tubes. The cost of tree tubes, and the time that went into installing bud caps each year were not all that much greater than the other treatments but did make a difference. See the file "Tree costs and labor" for details.

Tree and labor costs were in part 2 of this study, the silvopasture establishment, were high at over $65 per tree in each treatment. This was largely due to the cost of fruit trees and irrigation. Mulching and herbicide required the greatest hours/tree over three years (0.51 hours per tree), while clipped pasture grasses required the least amount of labor (0.43 hours per tree). 

Cost of the mulching treatment and the pasture grass treatments were the lowest compared to herbicide and clover treatments. Herbicide was the most expensive treatment. See "Tree Costs and Labor" for detailed tables. 

Mulching stands out as a viable treatment because of its trend toward greater tree growth and low out-of-pocket cost since the mulch is a waste produce on-farm. However, mulching would be expensive if the mulch were to be trucked in. Mulching also required more labor to apply during the first year but the effects of it lasted beyond the first year. The tradeoff here is a higher upfront labor demand but with payoffs in later years. 

Research conclusions:

Part 1: 

Tree tubes provided the best protection from deer but did not allow trees to grow taller than the tube, and some tubes blew over. Shrubs provided protection for half of the trees and competition for the other half. Bud caps did not work because deer browsed trees in the summer. 

Part 2: 

Mulch of waste hay trended toward the best form of protection from grass competition. Mortality due to deer browse was a major concern while damage due to livestock was minimal. If I were to do this again I would put a deer exclusion fence around the whole orchard and then keep fruit tree rows wide (25'-30') in order to minimize cattle/tree interactions. Polywire worked well to keep cattle from damaging fruit trees in areas with wider rows, but polywire needed to be on to work. Fruit tree variety should be studied further to determine which species/varieties are most productive in silvopastures. 

Part 3: 

Fruit trees were expensive to establish at over $65 per tree with all costs considered. However, significant savings could be had if the producer started their own seedlings instead of buying in trees at $35+ each. Additionally, volume discounts would apply for larger plantings. Mulching was likely the best option because of its cost effectiveness and positive impact on growth, however it requires an initial labor demand to apply the mulch. 

Participation Summary
1 Farmer participating in research

Education & Outreach Activities and Participation Summary

10 Consultations
1 On-farm demonstrations
2 Tours
1 Webinars / talks / presentations
1 Workshop field days
4 Other educational activities: Guest Lectures were presented to multiple school and professional groups, including two Universities and professional foresters

Participation Summary:

65 Farmers
33 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

50 farmers and extension agents attended a silvopasture 101 workshop we hosted on the farm in August 2019. A quarter of this workshop was devoted to silvopasture regeneration and the research plots here were the highlight of that. They were valuable in demonstrating different strategies for establishing trees in open pastures as well as the challenges of deer browse. 

Field tours were limited in 2020 due to COVID19. I did host a group of four NRCS officials from CT, MA, and RI in November 2020 to discuss silvopastures and this research was a focus of that discussion. 

I also included this study in two online presentations to high school students in Maryland and New Haven, CT who were learning about sustainable agriculture. I also included this study in a lecture on silvopasture to graduate students at Yale University in the fall of 2020 and fall of 2021. In February of 2021 I included this research into a silvopasture presentation I gave to sustainable agriculture focused students at Ball State University. 

On October 18, 2021 I hosted a webinar on this research and it was attended live by 6 people. Guests were interactive and asked great questions. I also presented this research to foresters at the 2021 New England Society of American Foresters meeting in March, 10 foresters were in attendance. 

I also hosted a pasture walk demonstration on this research on October 15, 2021. We had 17 farmers attend this pasture walk where the focus was agroforestry tree regeneration and silvopasture. regenerating trees in silvopasture systems in place at Hidden Blossom Farm. We discussed 3 years of fruit tree establishment into pastures grazed with beef cattle. We also walked through and discussed a forest conversion to silvopasture which was currently being established through logging and seeding forages. Tree protection strategies to prevent deer damage were also be part of the pasture walk. A subset of these farmers had been on the 2019 on-farm workshop and found it rewarding to see the progress of tree growth over 2 additional growing seasons. 

Learning Outcomes

65 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

We had positive responses regarding the following during our 2019-2021 farm silvopasture workshops: 

  • The value of soil health
  • Methods for silvopasture
  • Grazing and fencing techniques
  • How to implement silvopasture successfully

Project Outcomes

3 New working collaborations
Project outcomes:

This project was useful in helping our farm connect with NRCS and other conservation groups related to grazing in our region. The initial workshop held in 2019 led to collaborations for a fencing video related to pasture management with the New England Grazing Network. The site has also served as a demonstration for producers in 2019, NRCS professionals in 2020, and additional farmers in 2021 during the pasture walk. This project has allowed Hidden Blossom Farm to demonstrate that establishing silvopastures from treeless pasture is not only possible but effective. Results of this study have helped our farm and other farms by better being able to plan for silvopasture establishment while minimizing wildlife and livestock damage. This project provided significant insight into proper fruit tree variety selection, tree protection strategies, grass competition strategies, and tree layout when establishing silvopasture. Future planted silvopastures on Hidden Blossom Farm will be directly informed by the results of this study and I expect other farms will benefit from this knowledge as well. We are in preliminary discussions with a non-profit to use the silvopastures established in this study as part of a bigger design to make Hidden Blossom Farm an place for demonstrating silvopasture practices. In short, this project helped to catalyze our ability to demonstrate silvopasture while providing insight into how to best proceed when planting and establishing silvopastures. 

Assessment of Project Approach and Areas of Further Study:

If I were to conduct this study again I would put deer fencing around the fruit tree silvopastures. Deer damage was avoidable but it would have required a full exclusion fence around the silvopasture, which I hope to install in a year or two. I also expect that this fence will be needed to keep bears out as the fruit trees begin to set fruit. 

The biggest change I would make if i were to do this again would be to have a minimum spacing of 25' between rows of tree in the silvopastures. This will allow alleys to be wide enough that cattle do not pressure each other toward trees, and reduce cattle damage on the trees. This project makes me think that 25'-30' spacing between rows of trees is ideal because our wider alleys (25') had the least damage to trees. Alley width as it relates to livestock/tree interactions would be in interesting future study. 

Another change I would have made would have been to use square 1" wooden stakes to hold up tree tubes instead of round bamboo stakes. The bamboo stakes moved in the wind and rounded out their holes - resulting in them not holding the tree tubes on effectively. I did use square stakes for some trees planted after this study and they were much more effective in keeping tree tubes on trees in areas of high wind. 

Another take-home from this study was that planting taller trees in silvopastures, and keeping trees vigorous, will help them get above browse height and to a robust size faster. 

Areas for future research that resulted from this study include: 

  • Investigating the extent of which shrubs inhibit tree regeneration and protect established trees in agroforestry and forest management 
  • Variety trial for fruit trees in silvopasture for vigor and growth
  • How long, and to what size, should trees in silvopastures be before cattle protection fencing can be removed? What about for other livestock? The trees in this study are not yet large enough in diameter and height to be resistant to cattle impact (such as rubbing and browsing leaves), however after 2 years they are likely robust enough to handle sheep grazing. 
  • Will taller tree tubes work to allow agroforestry plantings to get above deer browse height without negative effects? 
  • Did the clover treatment attract deer to fruit tree plantings? 
  • How can the cost of fruit tree plantings be reduced? Would it be better to graft our own trees and plant them when small or when tall? If trees purchased are smaller, thus less cost, would it be better to purchase them small and growth them tall (in pots or a nursery) before planting out in the silvopasture? 
  • What alley widths, and planting designs, would be most effective for establishing silvopastures among differing uses (timber, fruit, nuts)? 
  • How will forage composition and quality change as silvopasture planted in treeless pastures develop over time? 
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.