The role of agroforestry practices in a healthy farm

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.The University of Nebraska-Lincoln is developing a Healthy Farm Index that reflects a vision of sustainable farming. The index uses multiple indicators within ecological, environmental, and socio-economic categories to assess production, biodiversity, and ecosystem services provided by sustainable farm systems. The value of various agroforestry practices is reflected in these indicators as a component that improves farm profitability, conserves biological diversity, and enhances ecosystem services to and from agroecosystems. Agricultural systems are typically managed to maximize the provision of food and fiber. In contrast, proponents of sustainable agricultural systems seek to optimize long-term outcomes that include multiple components of agroecosystems and rewards for farmers who use sustainable practices. Understanding how shape, arrangement, and management of agroforestry landscape features affect different components of the farm system is important, as is recognizing tradeoffs. Understanding tradeoffs requires whole farm analysis and management. Management objectives help plan the shape and arrangement of landscape features. In this paper we will discuss how the use and arrangement of woody landscape features will be included in the Healthy Farm Index. Four participating organic farms in eastern Nebraska provide examples of the influence of woody land cover on the index scores. The structure of the index allows for the integration of current and future components. The index will be a mechanism for communicating interdisciplinary data toward farm practices and policy that optimize food production, biodiversity, and ecosystem services.James R. Brandle (1), Ron. J. Johnson (2), and John E. Quinn (1) ; 1. School of Natural Resources, University of Nebraska Lincoln, Lincoln, NE. 2. Department of Forestry & Natural Resources, Clemson University, Clemson, SC.Includes bibliographical references

A farm-scale biodiversity and ecosystem services assessment tool: The healthy farm index

Farm management focused on maximizing biomass production results in biological simplification and ultimately a degraded production potential for the future. Despite the large and growing body of evidence pointing to the need to restore biodiversity to farm systems, incorporation of biodiversity and ecosystem services into local agricultural land use decision- making remains limited. The lack of planned and associated biodiversity may reduce resiliency of local managed ecosystems and add management costs; however, the trade-off for individual landowners of greater diversity is increased management complexity and uncertainty. To assist farmers in managing biodiversity and to encourage ecological thinking, we developed the Healthy Farm Index, a farm-scale tool that complements existing farm assessment tools by integrating multiple metrics and outputs suitable for applied decision-making and annual evaluation. In this article, we describe the impetus for the index development and the structure of the index and through a case study apply the index and discuss its varied outputs and applications

Biotic interactions in organic farm systems

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Fire, drought, and grazing were primary ecological drivers of the historical Great Plains' prairie ecosystem. The suppression of fire, a shift in grazing and cropping systems, and the introduction of windbreaks and other woody vegetation altered the landscape. The abundance, vertical diversity, and composition of woody species have noticeably increased. A subsequent shift has been documented in relative abundance of bird species in the state, with shrubland and edge species filling the ecological niche created with the conversion of many cropland acres to woodland. Shrubland and edge birds may fill an important functional role in agroecosystems. Organic farms frequently have greater habitat heterogeneity then other farm types. Agroforesty is an important component of this habitat diversity. To quantify the effect of woody land-use and land-cover on biodiversity and to assess the functionality of avian species as predators in organic farm systems, avian and insect diversity were sampled on 23 organic farms in eastern Nebraska and Kansas in 2007 and 2008. Species response to the presence and arrangement of woodland cover on farms is of great interest. An N-mixture model was used to estimate abundance and detectability of farmland bird species. Results from these analyses will be used to assess the functional role of birds and explore relationships between insect and bird communities to determine whether woodland edge bird species have the potential to effectively suppress crop pests on organic farms.John E. Quinn (1), Ron. J. Johnson (2), and James R. Brandle (1) ; 1. School of Natural Resources, University of Nebraska Lincoln, Lincoln, NE. 2. Department of Forestry & Natural Resources, Clemson University, Clemson, SC.Includes bibliographical references

Avian Foraging Patterns in Crop Field Edges Adjacent to Woody Habitat

As natural predators of pest insects, woodland birds provide biological pest suppression in crop fields adjacent to woody edges. Although many birds using these habitats forage widely, earlier studies have found that most foraging activity occurs within 50 m of the woody edge. The goals of this study were to determine the primary area of use, or functional edge, for birds foraging in crop fields adjacent to woody edges, and to evaluate their foraging distance patterns. During the summers of 2005 and 2006, avian foraging behavior was observed at 12 research sites in east central Nebraska that contained either a shelterbelt or woody riparian edge. At each site, perches were provided at 10 m intervals out from the edge and insect larvae were placed in feeders at random locations to simulate a pest insect food resource. Birds were recorded foraging in five distance categories out from the edge (0–10, 10–20, 20–30, 30–40, and 40–50 m). Seven species foraged primarily within 20 m of the edge (72% all observations; 79% without perch or feeder observations). Ten species foraged throughout the plots but six of these generally foraged more often (45% and 49%) and four less often (30% and 30%) within 20 m of the edge. The 13 species that tended to forage more often within 20 m of the edge, with 56% of their foraging overall in this area, also tended to forage farther when perch and feeder observations were included, indicating willingness to forage farther when food resources were available. Based on a repeated measures analysis of variance, foraging distances appeared to be greater at sites with soybean as the planted crop, although this apparent trend was significant for only some species. There was no clear difference in foraging distances outward from shelterbelt versus riparian sites. These results indicate that conservation efforts within the 20 m functional edge offer potential to enhance the sustainability of both birds and crops in agricultural

Avian Foraging Patterns in Crop Field Edges Adjacent to Woody Habitat

As natural predators of pest insects, woodland birds provide biological pest suppression in crop fields adjacent to woody edges. Although many birds using these habitats forage widely, earlier studies have found that most foraging activity occurs within 50 m of the woody edge. The goals of this study were to determine the primary area of use, or functional edge, for birds foraging in crop fields adjacent to woody edges, and to evaluate their foraging distance patterns. During the summers of 2005 and 2006, avian foraging behavior was observed at 12 research sites in east central Nebraska that contained either a shelterbelt or woody riparian edge. At each site, perches were provided at 10 m intervals out from the edge and insect larvae were placed in feeders at random locations to simulate a pest insect food resource. Birds were recorded foraging in five distance categories out from the edge (0–10, 10–20, 20–30, 30–40, and 40–50 m). Seven species foraged primarily within 20 m of the edge (72% all observations; 79% without perch or feeder observations). Ten species foraged throughout the plots but six of these generally foraged more often (45% and 49%) and four less often (30% and 30%) within 20 m of the edge. The 13 species that tended to forage more often within 20 m of the edge, with 56% of their foraging overall in this area, also tended to forage farther when perch and feeder observations were included, indicating willingness to forage farther when food resources were available. Based on a repeated measures analysis of variance, foraging distances appeared to be greater at sites with soybean as the planted crop, although this apparent trend was significant for only some species. There was no clear difference in foraging distances outward from shelterbelt versus riparian sites. These results indicate that conservation efforts within the 20 m functional edge offer potential to enhance the sustainability of both birds and crops in agricultural

Kink-boundary collisions in a two dimensional scalar field theory

In a two-dimensional toy model, motivated from five-dimensional heterotic M-theory, we study the collision of scalar field kinks with boundaries. By numerical simulation of the full two-dimensional theory, we find that the kink is always inelastically reflected with a model-independent fraction of its kinetic energy converted into radiation. We show that the reflection can be analytically understood as a fluctuation around the scalar field vacuum. This picture suggests the possibility of spontaneous emission of kinks from the boundary due to small perturbations in the bulk. We verify this picture numerically by showing that the radiation emitted from the collision of an initial single kink eventually leads to a bulk populated by many kinks. Consequently, processes changing the boundary charges are practically unavoidable in this system. We speculate that the system has a universal final state consisting of a stack of kinks, their number being determined by the initial energy

Moving Five-Branes in Low-Energy Heterotic M-Theory

We construct cosmological solutions of four-dimensional effective heterotic M-theory with a moving five-brane and evolving dilaton and T modulus. It is shown that the five-brane generates a transition between two asymptotic rolling-radii solutions. Moreover, the five-brane motion always drives the solutions towards strong coupling asymptotically. We present an explicit example of a negative-time branch solution which ends in a brane collision accompanied by a small-instanton transition. The five-dimensional origin of some of our solutions is also discussed.Comment: 16 pages, Latex, 3 eps figure

White-tailed Deer Browsing and Rubbing Preferences for Trees and Shrubs That Produce Nontimber Forest Products

Nontimber forest products (food, herbal medicinals, and woody floral and handicraft products) produced in forest, agroforestry, and horticultural systems can be important sources of income to landowners. White-tailed deer (Odocoileus virginianus) can reduce the quality, quantity, and profitability of forest products by browsing twigs and rubbing stems, resulting in direct and indirect losses to production enterprises. We evaluated deer damage (frequency and intensity of browsing and rubbing) sustained by 26 species of trees and shrubs, the relationships among morphological features of trees and shrubs to damage levels, and the economic impacts of deer damage on the production of nontimber forest products. Levels of browsing were high (frequency \u3e93% and intensity \u3e50%) in most species of trees and shrubs, with the highest intensity (\u3e60%) occurring in chinese chestnut (Castanea mollisima) and dogwood (Cornus spp.), and the lowest (Ginkgo biloba), curly willow (Salix matsudana), ‘Scarlet Curls’ curly willow, smooth sumac (Rhus glabra), and pussy willow (Salix caprea). Species of trees or shrubs with one or a few stout stems unprotected by dense branching [e.g., american elderberry (Sambucus canadensis), smooth sumac, and curly willow] sustained the most damage by rubbing. Trees and shrubs with many small diameter stems or with dense tangled branching [e.g. redozier dogwood (Cornus sericea), forsythia (Forsythia suspensa), ‘Flame’ willow (Salix alba), and ‘Streamco’ basket willow (Salix purpurea)] were damaged the least by rubbing. Annual economic costs of deer damage to producers of nontimber forest products can range from $26/acre for pussy willow to$1595/acre for curly willow

Phenomenology of heterotic M-theory with five-branes

We analyze some phenomenological implications of heterotic M-theory with five-branes. Recent results for the effective 4-dimensional action are used to perform a systematic analysis of the parameter space, finding the restrictions that result from requiring the volume of the Calabi-Yau to remain positive. Then the different scales of the theory, namely, the 11-dimensional Planck mass, the compactification scale and the orbifold scale, are evaluated. The expressions for the soft supersymmetry-breaking terms are computed and discussed in detail for the whole parameter space. With this information we study the theoretical predictions for the supersymmetric contribution to the muon anomalous magnetic moment, using the recent experimental result as a constraint on the parameter space. We finally analyze the neutralino as a dark matter candidate in this construction. In particular, the neutralino-nucleon cross-section is computed and compared with the sensitivities explored by present dark matter detectors.Comment: Final version to appear in Phys. Rev. D. Some comments and references added. 37 pages, 19 figure

Beauty is Attractive: Moduli Trapping at Enhanced Symmetry Points

We study quantum effects on moduli dynamics arising from the production of particles which are light at special points in moduli space. The resulting forces trap the moduli at these points, which often exhibit enhanced symmetry. Moduli trapping occurs in time-dependent quantum field theory, as well as in systems of moving D-branes, where it leads the branes to combine into stacks. Trapping also occurs in an expanding universe, though the range over which the moduli can roll is limited by Hubble friction. We observe that a scalar field trapped on a steep potential can induce a stage of acceleration of the universe, which we call trapped inflation. Moduli trapping ameliorates the cosmological moduli problem and may affect vacuum selection. In particular, rolling moduli are most powerfully attracted to the points with the largest number of light particles, which are often the points of greatest symmetry. Given suitable assumptions about the dynamics of the very early universe, this effect might help to explain why among the plethora of possible vacuum states of string theory, we appear to live in one with a large number of light particles and (spontaneously broken) symmetries. In other words, some of the surprising properties of our world might arise not through pure chance or miraculous cancellations, but through a natural selection mechanism during dynamical evolution.Comment: 50 pages, 4 figures; v2: added references and an appendix describing a related classical proces