Within Shenandoah National Park in Virginia, northeast USA, large meadows within the generally forested landscape support high floristic diversity. Although probably of human origin, they are considered of conservation value. However, they are gradually becoming invaded by shrubs and trees. Here, a study undertaken in the largest meadow, Big Meadows (over 40 ha; 1,060 m altitude),which investigated the effects of mowing and burning on soil nutrients and shrub and tree control is summarised.
For several years the meadows were mown in November in an attempt to retard woody growth with little success. In experimental trials, comparisons were made between areas where growth of black locust Robinia pseudo-acacia (the main invasive woody species) was dense and areas where grasses, sedges and herbs were more common.
Two strips approximately 80 m wide by 160 m long were established in each vegetation type. Within each strip two quadrats (40 x 40 m) were selected for each of the following treatments (i.e. 2 replicates/treatment): 1) mowed then burned; 2) mowed, not burned; 3) burned without mowing; and 4) control (no treatment). Mowing was undertaken in November 1974, and burns applied on 20 April 1975.
On 16 April prior to burning, and again on 15 June, 10 samples were collected for soil nutrient analysis from the upper mineral soil (0-5 cm depth) in each quadrat.
Concentrations of potassium, calcium and magnesium were significantly higher in the burn treatment. Mowing had no significant effect on concentrations, as compared to controls. Soil pH (>< 4.9-5.1) was unaffected by treatment.
Burned plots tended to have higher nitrate levels while mowed treatments were generally lower (but results were rather variable). Neither mowing nor burning affected phosphate concentrations.
Burning appeared as efficient as mowing in keeping invading shrubs and trees under control (no data presented in original paper). Although burning may result in more fertile soils (perhaps promoting more luxuriant growth), no detrimental effects on vegetation or soil were apparent. Burning is much less expensive than mowing, thus it might be a viable management option to mowing in woody species control. Longer term studies are however required.
If using or referring to this published study, please read and quote the original paper, this can be viewed at: https://www.uair.arizona.edu/holdings/journal/issue?r=http://jrm.library.arizona.edu/Volume29/Number6/