Author
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Feldhake, Charles |
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Submitted to: Agroforestry Systems
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/1/2001 Publication Date: 4/15/2001 Citation: Feldhake, C.M. 2001. Microclimate of a natural pasture under planted "Robinia pseudoacacia" in central Appalachia, West Virginia. Agroforestry Systems. 50:297-303. Interpretive Summary: Improving the productivity of steep Appalachian pastures with low fertility soils using conventional fertilizer and equipment for application is difficult. Black locust trees grown within these pastures offers potential for increasing soil nitrogen and concentrating chemical bases near the soil surface for forage uptake. Data quantifying changes in light, temperature, ,and soil water in response to the presence of black locust trees is not available for assessing the impact of trees on forage growth. Light intensity and quality was quantified as a function of distance from tree canopies under sunny and cloudy conditions. Soil water and temperature effects mediated by black locust trees on pasture were measured under both normal rainfall and drought conditions. The results suggest the trees have little impact on soil water available for forage uptake. Light penetration under the tree canopy was highest with about 30% cloud cover. Shade from trees greatly reduced surface soil temperatures during drought. These results suggest black locust has a moderating effect on forage microclimate when planted in a configuration where trees intercept less than half of incoming pasture solar radiation. This information can help improve pasture management for small hill land farms around rural Appalachian towns. This information will benefit scientists researching better management systems for small hill land farms and will benefit rural communities dependent in part on an economy fueled by these farms. Technical Abstract: The conditions under which forages yield more under tree canopies than in open fields are not well understood. This study was conducted to determine how microclimate experienced by forages in central Appalachia is modified by black locust tree canopies. The effect of tree row location relative to forage growing point was evaluated for it's impact on soil water, photsynthetically active radiation (PAR), red/far-red ratio, and surface soil temperature. There was no consistent spatial dependency relating tree rows to soil water levels. The level of PAR under tree canopies nearly doubled as cloud cover increased from 0 to 25%. The red/far-red ratio decreased from 1.16 to 0.2 for forages growing between tree rows compared to forage within tree rows. Surface soil temperature remained nearly constant (1.5-2 oC increase) over a day under tree canopies but increased 8-12 oC at unshaded sites depending on soil water levels. Microclimate under black locust trees, while lower in PAR over all, had less extreme levels of both PAR and temperature to which plants needed to adapt. These data give insights that may contribute to our understanding of why forage productivity may be maintained or even increase as a result of pasture being shaded by black locust trees. |
