Progress 11/01/00 to 10/31/06

Outputs
The shelterbelt project was initiated in the mid-60s by Walter Bagley with the planting of six, 40 acre, replicated shelterbelt systems. Over the past 35 years crop yields have been recorded on corn, wheat, sorghum, and soybean. Long term averages of yield enhancements are between 8 and 15 percent for all crops tested. This includes a yield of 0 on the acres planted to trees. For wheat, the benefits flow from the protection offered during the winter. For corn, sorghum, and soybean, the benefits appear to flow from increased water use efficiency and in the case of soybean a change in canopy structure that allows greater light penetration into the lower canopy. Vegetable studies indicated positive benefits in both yield and quality for snap bean, pepper, asparagus and cantaloup. All four crops matured earlier providing a marketing advantage. Work on the mechanisms involved in windspeed reductions confirmed that the 3 dimensional structure of a windbreak determines the flow fields in the sheltered zones and that this structure needs to be defined in terms of the amount and arrangement of both the solid and open portions of the windbreak as well as the amount and arrangement of the surface area of the individual elements within the windbreak. A model was developed to calculate the flow fields. Work continues on calculating the effects of the flow fields on temperature and humidity gradients within the sheltered zones. Over the last several years work has focused on the impact of woody plants in the agricultural landscape and how it impacts predator prey relationships. No evidence has been found to indicate that pest insects preferentially overwinter in the shelterbelts at the study site. Evidence has been collected that indicates the value of shelterbelts as habitat for predatory bird species. Birds will forage into crop fields from woody edges and have a preference for the adjacent 20 meters of the crop field.

Impacts
A better understanding of how a windbreak influences the wind flow will allow us to design and test better windbreak designs for use on farms, ranches and rural areas of the Midwest. Windbreaks have a potential role to play in carbon balance issues, addressing both carbon storage and reductions in carbon dioxide emission. Developing efficient designs will make these conservation practices more economical and practical for producers and others throughout the agricultural Midwest. An aggressive program to encourage the planting of windbreaks could provide significant wind erosion control, wildlife habitat, and carbon sequestration benefits, all of which provide economic returns to landowners.

Publications

• Hodges, L., E. Daningsih, and J.R. Brandle, 2006. Comparison of an antitranspirant spray, a polyacrylamide gel, and wind protection on early growth of muskmelon. HortScience 41(2):361-366.
• J.C. Kriz, S.D. Danielson, J.R. Brandle, and E.E. Blankenship, 2006. Relative abundance of exotic and native Coccinellidae (Coleoptera) in southeast Nebraska alfalfa. Journal of Entomological Science 41(1):84-86.
• Kriz, James C., Stephen D. Danielson, James R. Brandle, Erin E. Blankenship, and Geoff M. Henebry, 2006. Effects of aphid (Homoptera) abundance and surrounding vegetation on the enciunter rate of Coccinellidae (Coleoptera), Chrysopidae(Neuroptera) and Nabidae (Hemiptera) in alfalfa. Journal of Entomological Science 41(3):211-220.
• A.Samal, J.R. Brandle,and D. Zhang, 2006. Texture as the basis for individual tree identificaition. Information Sciences, 176(5):565-576.
• Zhou, X.H., J.R. Brandle, M.M. Schoeneberger, and T. Awada, 2007 Developing above ground biomass equations for open-grown multiple-stemmed tree species: Shelterbelt grown Russian-olive. Ecological Modelling. (in press).
• Samal, A., J.R. Brandle, and D.S. Zhang. 2007. A method for estimating fractal dimension of tree crowns from digital images. International Journal of Pattern Recognition and Artificial Intelligence (in press)
• Windbreaks for fruit and vegetable crops. 2006. University of Nebraska Extension Circular EC-06-1779

Progress 10/01/04 to 09/30/05

Outputs
Field windbreak studies continue to indicate increases in crop yields for corn, soybean and wheat. The data were used to verify the SAMS model (Shelterbelt Agroforestry Modeling System) being developed in conjunction with Iowa State. Windbreak structure analyses have improved our ability to predict windspeed at various locations within the sheltered zone. Field studies on Coccinellidae species diversity indicated the value of protection to lady beetle development. Coordination of harvest timing and beetle development with availability of alternative habitat is critical to maintaining viable predator populations. Behavioral studies on bird feeding patterns relative to windbreaks were initiated and preliminary studies indicate a relationship between distance traveled from woody cover to food to vary with size of bird. Biomass studies resulted in the completion of volume tables for windbreak grown trees. Species include green ash, eastern redcedar, ponderosa pine, Russian olive and caragana.

Impacts
A better understanding of how a windbreak influences the wind flow will allow us to design and test better windbreak designs for use on farms, ranches and rural areas of the Midwest. Windbreaks have a potential role to play in carbon balance issues, addressing both carbon storage and reductions in carbon dioxide emission. Developing efficient designs will make these conservation practices more economical and practical for producers and others throughout the agricultural Midwest. An aggressive program to encourage the planting of windbreaks could provide significant wind erosion control, wildlife habitat, and carbon sequestration benefits, all of which provide economic returns to landowners.

Publications

• Mize, C., J. Brandle, M. Schoeneberger, and G. Bentrup (2006) Ecological function, development, and design of shelterbelt systems in North America. Agroforestry Systems. (in press)
• Helmers, G. and J. R. Brandle, (2005) Optimum windbreak spacing in Great Plains Agriculture. Great Plains Research 15:179-198.
• Skelton, P., S.J. Josiah, J.W. King, J.R. Brandle, G.A. Helmers, and C.A. Francis, (2005) Adoption of riparian forest buffers on private lands in Nebraska, USA. Journal of Small-Scale Forest Economics, Management and Policy 4:185-204.
• Guo, Q., J. Brandle, M. Schonenberger, and D. Beuttner (2005) Simulating the dynamics of linear forests in Great Plains agroecosystems under changing climates. Canadian Journal of Forest Research 34:2564-2572
• Guo, Q., M. Taper, M. Schonenberger, and J. Brandle (2005) Spatial-temporal population dynamics across species range: from centre to margin. OIKOS 108:47-57.
• Zhou, X.H., J.R. Brandle, C.W. Mize, and E.S. Takle (2005) Three-dimensional aerodynamic structure of a tree shelterbelt: Definition, characterization and working models. Agroforestry Systems 63:133-147.

Progress 10/01/03 to 09/30/04

Outputs
Based on various studies, the overall aerodynamic structure of a shelterbelt in three dimensions was defined in terms of the amount and arrangement of the solid and open portions of the barrier. In order to associate the defined structure with wind speed, turbulent stress, and pressure; we used two structural descriptors, the spatial functions of vegetative surface area density and cubic density. Field studies verified the ability of the spatial functions to define the windflow patterns. Application of these structural descriptors to simulate the influence of a shelterbelt on temperature and humidity in the sheltered zone is under development. Field studies to determine the influence of a shelterbelt on Coccinellidae species were initiated. Preliminary analysis indicates that landscape structure surrounding an alfalfa field affects abundance of some but not all species. The relationship between microclimate and rate of Coccinellidae development is the focus of a new field study. Efforts to estimate carbon stocks of windbreaks continued and a spatial growth model was developed. The model can be used to predict the biomass that would accumulate in a green ash windbreak on any given site in Nebraska. Data collection on other species continues and additional species will be incorporated into the model. Data was also collected from Montana and the model extended to produce volume tables for windbreak species used in eastern Montana. Methodology to estimate the indirect benefits of shelterbelts on the carbon balance equation are underway.

Impacts
A better understanding of how a windbreak influences the wind flow will allow us to design and test better windbreak designs for use on farms, ranches and rural areas of the Midwest. Windbreaks have a potential role to play in carbon balance issues, addressing both carbon storage and reductions in carbon dioxide emission. Developing efficient designs will make these conservation practices more economical and practical for producers and others throughout the agricultural Midwest. An aggressive program to encourage the planting of windbreaks could provide significant wind erosion control, wildlife habitat, and carbon sequestration benefits, all of which provide economic returns to landowners.

Publications

• Brandle, J.R., 2004. Shelterbelts. In: Encyclopedia of the Great Plains. D.J. Wishart (ed) page 639. University of Nebraska Press, Lincoln, NE.
• Brandle, J.R., L. Hodges, X, Zhou, 2004. Windbreaks in North American agricultural systems. Agroforestry Systems 61:65-78.
• Zhou, X.H., J.R. Brandle, C.W. Mize, E.S. Takle, 2004. Three-dimensional aerodynamic structure of a tree shelterbelts: Definition, characterization ans working models. Agroforestry Systems (in press).
• Hodges, L. M.N. Suratman, J,.R. Brandle, K.G. Hubbard, 2004. Growth and yield of snap beans as affected by wind protection and microclimate changes due to shelterbelts and planting dates. HortScience 39:996-1004.
• Takle, E.S., W.J. Massman, J.R. Brandle, R.A. Schmidt, X.H. Zhou, I.V. Litvina, R. Garcia, G. Doyle, C.W. Rice, 2004. Influence of high-frequency ambient pressure pumping on carbon dioxide efflux from soil. Agricultural and Forest Meteorology 124:193-206.
• Josiah, S.J., R. St. Pierre, H. Brott, J.R. Brandle, 2004. Productive conservation: Diversifying farm enterprises by producing specialty woody products in agroforestry systems. Journal of Sustainable Agriculture 22:93-108.
• Kriz, James C., 2003. Predaceous insect abundance as affected by landscape structure and temporal distribution in alfalfa fields in east central Nebraska. M.S. thesis, Department of Entomology, University of Nebraska, Lincoln, NE.

Progress 10/01/02 to 09/30/03

Outputs
The drag force created by a full-scale model windbreak on wind flow was directly measured with a newly constructed shelterbelt drag force system. The system consists of a pair of 9 m sections of triangular support rack resting on two load cell platforms. Each platform consists of two pieces of aluminum channel with a double-rail guide located between the channel pieces. A load cell is located at one end of each platform such that force applied to the barrier is measured by the load cells. The system was tested using artificial Christmas trees with known surface area and volume. Various barrier and canopy arrangements were measured and compared. Results indicated the system was very sensitive to changes in windbreak structure and clearly demonstrated that the drag force of the barrier increases with increasing surface area and that the arrangement of surface area within the windbreak has a significant influence on the drag coefficient. Using static pressure differences, wind speed changes, and turbulence estimates, an indirect method for calculating drag coefficient was developed and tested using the shelterbelt drag force system. The next step is to apply the indirect method to natural shelterbelts and incorporate the drag term into our modeling efforts. This will allow us to better predict microclimate changes within the sheltered areas. Biomass data for two additional windbreak species, Russian Olive and Caragana were collected. Volume tables for windbreak grown ponderosa pine were completed and a spatial model for predicting biomass based on environmental conditions, age and site is in the final stages of testing. Graduate students supported: 5 (4 MS and 1PhD).

Impacts
A better understanding of how a windbreak influences the wind flow will allow us to design and test better windbreak designs for use on farms, ranches and rural areas of the Midwest. Windbreaks have a potential role to play in carbon balance issues, addressing both carbon storage and reductions in carbon dioxide emission. Developing efficient designs will make these conservation practices more economical and practical for producers and others throughout the agricultural Midwest. An aggressive program to encourage the planting of windbreaks could provide significant wind erosion control, wildlife habitat, and carbon sequestration benefits, all of which provide economic returns to landowners.

Publications

• Hou, Q.J., L.J. Young, J.R. Brandle, and M.M. Schoeneberger, (2002) Spatial modeling of biomass in Nebraska windbreaks. Fourteenth Ann. Conf. on Applied Statistics, Manhattan, KS April 28-30, 2002, pages 202-216.
• Hou, Q.J., J. Brandle, K. Hubbard, M. Schoeneberger, C. Nieto, and C. Francis, (2003) Alteration of soil water content consequent to root-pruning at a windbreak/crop interface in Nebraska, USA. Agroforestry Systems 57:137-147.
• Brandle, J., X.H. Zhou, and L. Hodges, (2003) Agroforestry for enhancing water use efficiency. Encyclopedia of Water Science 19-21.
• Takle, E.S. J.R. Brandle, R.A. Schmidt, R. Garcia, I.V. Litvina, W.J. Massman, X. Zhou, G. Doyle, C.W. Rice, (2003) High-frequency pressure variations in the vicinity of a surface CO2 flux chamber. Agricultural and Forest Meteorology 114:245-250.

Progress 10/01/01 to 09/30/02

Outputs
The impact of the three dimensional structure of a windbreak on windflow patterns in the vicinity of a windbreak was clearly demonstrated. The amount of drag created by the windbreak is determined by the volume, surface area and shape of the branches, trunk and leaves or needles. Not only are the amounts of these elements important in determining flow fields around a windbreak but their arrangement within the windbreak contributes to magnitude of the turbulence created and amount of windspeed reduction within the sheltered zones. The question still remains as to the relative magnitude of each of these components. We do know that as the distribution of surface area and volume shifts upward within the windbreak, the amount of drag created by the windbreak increases. The next step is to relate these changes in drag to windspeed reductions and ultimately to the changes in microclimate created in the sheltered zones. Emphasis during the next year will be on developing an energy budget for a windbreak/crop situation and to estimate the influence of the windbreak on rates of water use within the sheltered zone. As a side benefit of the work to describe windbreak structure, biomass estimates of windbreak species are being developed. Data have been collected on 6 species; green ash, eastern redcedar, Rocky Mountain juniper, Austrian pine, Scotch pine and ponderosa pine. Equations and volume tables for windbreak grown trees are under development for use in estimating the amount of biomass and thus carbon, sequestered in windbreaks. Using developed equations and climate data from the Great Plains Region, methods for estimating biomass in windbreaks on a regional scale within the Great Plains are being developed using spatial statistical techniques. Graduate Students supported: 4 (3 MS and 1PhD)

Impacts
An aggressive program to encourage the planting of windbreaks on farms and ranches in the North Central region could provide significant conservation benefits in terms of wind erosion control and critical wildlife habitat in areas dominated by annual monocultures while at the same time maintaining or improving crop productivity. As a side benefit, these windbreaks would store ove 30 million metric tons of carbon over the next 20 years, reduce fossil fuel usage by over 11 million gallons per year and significantly reduce carbon dioxide emissions.

Publications

• Stepanek, L.J., J.R. Brandle, and M.O. Harrell, (2002) Assessment of microenvironmental conditions related to the use of synthetic sheet mulches for protecting newly planted trees in semi-arid environments. J. Sustainable Agriculture 19:15-34.
• Zhou, X.H., J.R. Brandle, E.S. Takle, C.W. Mize (2002) Estimation of the 3-dimensional aerodynamic structure of a green ash (Fraxinus pennsylvanica Marsh.) shelterbelt. Agricultural and Forest Meteorology 111:93-108.
• Brandle, J.R., X.H. Zhou, and L. Hodges (2002) How Windbreaks Work, University of Nebraska. EC-02-1763

Progress 10/01/00 to 09/30/01

Outputs
The value of windbreaks or shelterbelts continues to be demonstrated, providing producers with significant economic returns in the form of increased yields, improved crop quality, reduced input costs and numerous conservation benefits. We have begun to quantify the role of new windbreak plantings as a means of storing carbon to help mitigate the impacts of global climate change. Above ground biomass of green ash growing in two row windbreaks was two times greater than biomass predicated from established biomass equations based on forest grown trees. This additional biomass is attributed to the increased size of the branches in shelterbelt grown trees. Similar comparisons for other windbreak species are underway, with field data currently being collected in Nebraska and Montana. Understanding the influence of windbreak structure, the amount and arrangement of the solid and open portions of a windbreak, on the flow fields around the windbreak and the resulting microclimate changes in the protected zones are major goals of the project. Estimating the exchanges rates for heat and moisture are the first steps to incorporating these terms into the turbulence model. Energy balance terms, as well as wind speed, pressure, relative humidity, and soil moisture as influenced by a mature shelterbelt were measured over a full growing season. Both incoming and outgoing radiation was influenced by location relative to the shelterbelt. The horizontal profile of pressure measured in the vicinity of the shelterbelt closely matched simulated model results.

Impacts
An aggressive program to encourage the planting of windbreaks on farms and ranches in the North Central region could provide significant conservation benefits in terms of wind erosion control and critical wildlife habitat in areas dominated by annual monocultures while at the same time maintaining or improving crop productivity. As a side effect, these windbreaks would store over 30 million metric tons of carbon over the next 20 years, reduce fossil fuel usage by over 11 million gallons per year and significantly reduce carbon dioxide emissions.

Publications

• Danielson, S.D., J.R. Brandle, and L. Hodges, 2000. Parasitoids of the Bean leaf beetle (Coleoptera: Chrysomelidae) found in Nebraska soybean fields Journal of the Entomological Society 73:242-244.
• Danielson, S.D., J.R. Brandle, L. Hodges, and P. Srinivas, 2000. Bean leaf beetle (Coleoptera: Chrysomelidae) abundance in soybean fields protected and unprotected by shelterbelts. J. Entomol. Sci. 35:385-390.
• Easterling, W.E., J.R. Brandle, Q. Guo, C.J Hays, and D.S. Guertin, 2001. Simulating the impact of human land use change on forest composition in Great Plains agroecosystems with the Seedscape model. Ecological Modeling 140 (1-2):163-176.
• Guo, Q., 2000. Climate change and biodiversity conservation in Great Plains agroecosystems. Global Environmental Change 10:289-298.