Yield Mapping to Document Goose Grazing Impacts on Winter Wheat

Abstract

multiflorum Lam.) seed in the Willamette Valley, Oregon. In other studies, however, geese have reduced the In southwestern Washington and western Oregon, increasing numyield of winter wheat in relation to intensity of grazing bers of wintering Canada geese (Branta canadensis ) graze several farm crops including wheat (Triticum aestivum L.). Our objectives (Allen et al., 1985;Flegler et al., 1987) and to timing of were to develop methods to determine timing, intensity, and locations grazing (Kahl and Samson, 1984). of grazing, and to measure the impact of grazing on grain yield. Aerial Substantial yield losses in grass and cereal crops have photography with ground-truth photography and repeated samplbeen reported at a wide range of grazing levels by geese ing worked well to determine timing, intensity, and locations of graz- (Patterson, 1991). Estimating loss of yield at specific leving. Exclosures served as nongrazed controls. A yield-mapping-systemels of grazing, however, was difficult. Patterson (1991) equipped combine measured yields. All data collection points were suggested exclosures should be used to measure actual spatially located via differential global positioning system (DGPS) yield loss. technology, which allowed us to integrate all data spatially and tempo-Recent technologies such as geographical information rally via geographical information system (GIS) technology. Based systems (GIS) and global positioning systems (GPS) on yield-mapping-system data, goose grazing resulted in grain yield differences ranging from a 16% increase on part of one field to a 25% provide new opportunities to more accurately measure decrease on an area of a field heavily grazed in April, just before geese crop yield and damage caused by wildlife or other facmigrated north. Comparisons of exclosures (nongrazed controls) with tors. Geographical information systems have the ability paired plots provided variable results. Results from paired-plot comto spatially interrelate multiple files or data layers once parisons for three fields during 1998 were 25% reduction, no differthe layers are in geographic registration (Lillesand and ence, and 13% increase in grain yields in the paired plots available Kiefer, 1994). Global positioning systems can accurately for grazing vs. exclosures. Based on yield-mapping-system data, the determine the position of every sample point. Combinsame three fields experienced 19, 7, and 5% grain yield reductions ing these technologies provides visual representations due to goose grazing with the extent of reduction depending on a of changes through time (Anderson, 1996) and provides combination of timing, intensity, and extent of grazing. Paired plots the tools necessary to create yield maps. did not adequately represent grazing impacts on the fields. The yieldmapping system provided nearly complete coverage of the fields andWe designed our study to develop and evaluate methadequately captured grazing impacts. ods to achieve the following objectives: (i) identify locations grazed by geese, (ii) determ...

Human–Sheldgeese conflict in agricultural landscapes: Effects of environmental and anthropogenic predictors on Sheldgeese distribution in the southern Pampa, Argentina

“…Conflicts between goose populations and agriculture are common in many countries around the world as they forage on pastures and croplands (Borman et al, 2002;Amano et al, 2004;Fox et al, 2005;Wisz et al, 2008;Wood et al, 2013). Sheldgeese wintering in the Argentine Pampas are not an exception; in fact they have been a source of historical conflict with agricultural interests (Blanco and De la Balze, 2006).…”

Ecosystem services provided by waterbirds

“…The studies of waterfowl in California ricefields (Bird et al, 2000;van Groenigen et al, 2003) are the closest to date, since they quantify the removal of rice straw and weeds by ducks, but do not include a precise economic valuation. As in this case, exclosure experiments might be used to quantify the benefits of the pest-control service provided by waterbirds in other landscapes, just as they have been used to quantify the crop damage caused by some waterfowl (Parrott & Mckay, 2001;Borman et al, 2002). One way of valuing part of the dispersal service by waterbirds would be to calculate the replacement costs of planting manually the aquatic vegetation, or introducing the zooplankton and other invertebrates which actually become established in created or restored wetlands owing to their arrival via birds.…”

Delayed Cutting Stage in Dual Purpose Wheat: A Better Strategy to Control Weeds and Enhance Forage Production

“…However, many reports suggested that dual purpose wheat crop produce lower grain production. For example Borman et al [7] reported that yield reduction depends on a combination of timing, intensity and extent of grazing. Therefore, keeping in view the current demand of both grain and fodder production and yield losses due to weeds, this experiment was conducted to determine optimum cutting stage suitable for dual purpose wheat and weed population control.…”