PS 3-33 - Vegetative succession of mined forestland: effects of soil compaction and ripping management

Abstract:

Secondary succession of disturbed areas to forest often follows a standard trajectory, as woody species start to outcompete herbaceous species and ultimately shade them out. However, after some extreme types of disturbance, particularly those that dramatically alter the underlying substrate, reforestation often follows a slowed or altered trajectory, causing forest succession to be impeded. In Ohio’s Cuyahoga Valley National Park, between the cities of Akron and Cleveland, five sites previously mined for gravel and topsoil are being actively managed in order to return them to forestland, as a previously-implemented passive approach to management was not leading to reforestation. Several decades ago, to control erosion after mining completed, the topsoil was graded and compacted and various native and nonnative species were seeded, under the assumption that native trees would colonize the sites. As succession beyond this initial seeding had not yet been observed, in 2018-19 two of the sites were mechanically decompacted using 2m shanks to deeply till the soil. Vegetation was surveyed in 2018 from Sept-Oct prior to tillage and again in 2022 from June-September after tillage, using the same grid locations. These data were combined with co-located soils data taken at all plot locations.

Two of five surveyed sites were subject to the deep tilling treatment before pandemic restrictions modified management priorities at CVNP, leading to a natural before-after, control-impact study design. We compared vegetation and soil properties across time and in response to the deep-tillage treatment. The ripped plots were compared to the non-ripped sites with site location as a random effect. Vegetation data was also correlated to soil properties data. Our data suggest that ecological communities occurring in the non-ripped communities have not changed dramatically from the previous vegetative survey, while vegetation communities at the deep-tilled sites had undergone several key changes. Overall, vegetation communities were different between the ripped and non-ripped sites at the 2022 timepoint. A greater diversity of woody species were found at the ripped sites compared to the non-ripped sites. More invasive and nonnative species were found in the non-ripped sites than the ripped sites. Vegetation communities remain similar to the 2018 surveys at the non-ripped sites. These results support the assertion that compaction of the soil has been a major obstacle in impeding forest succession and that ripping the soil as an active management strategy has assisted in progressing succession of these highly disturbed sites.