Effects of Erosion Micro-Topographies on Plant Colonization on Weathered Gangue Dumps in Northeast China

Abstract

Micro-topography has been proved to be beneficial for plant colonization in severe environments. There are numerous micro-topographies caused by erosion of gangue dumps in the Northeast China, which can make plant colonization difficult. To determine how these micro-topographies affect plant colonization, the environment conditions, regeneration characteristics, vegetation characteristics of different erosion micro-topographies, such as bare slope, rill, ephemeral gully and deposit body were studied, and their relationships analyzed. The results showed that the content of particles with a size < 2 mm in the deposit body and bare slope was 33.7% and 7.8% higher than that in the ephemeral gully, respectively (p < 0.05), while the content of particles with a size > 20 mm in the ephemeral gully was 2.24 times higher than that in the deposit body. Except for the substrate water content, the substrate temperature and the surface humidity and temperature of the ephemeral gully were significantly different from those of the deposit body (p < 0.05); the surface temperature was the highest (54.6 °C) while the surface humidity and the substrate water content were the lowest among the erosion micro-topographies. The vegetation coverage, the plant and seedling density of the deposit body were significantly higher than those of the ephemeral gully (p < 0.05), with differences of 5.26, 35.9 and 16.8 times, respectively. The vegetation characteristics (Vdc) were more affected by the regeneration characteristics (Rc) as well as surface humidity and temperature (Sht), while Rc was significantly affected by Sht, which was extremely significantly affected by the soil physical properties and substrate water and temperature (p < 0.01). Different plant species had different responses to the environmental conditions of the erosion micro-topographies. In conclusion, the deposit body and rill are likely to promote plant colonization, which is driven mainly by the seed supply and comfortable growing conditions. The ephemeral gully is not suited to plant colonization because of its unhealthy mechanical composition and strong runoff scouring, and because it is prone to drought, high temperature, and a lack of seeds.

Micro-topographies formed by erosion can drive seedling emergence by rebuilding micro-habitats on weathered waste dumps in northeastern China

“…However, our previous research showed that although the environmental conditions were inadequate for plant colonization on most parts of the waste dumps, some plants were able to colonize and distribute in discrete areas. This indicates that some erosion micro-topographies can drive plant colonization (Wang et al, 2022). Similar results were also found on other waste dumps in this research.…”

“…The mechanical composition was determined by calculating the content percentage of each particle group using the drainage method. The substrate particles were classified according to the characteristic substrate particle size of the waste dumps (Wang et al, 2022) as fine grain (particle size <2 mm), middle-coarse grain (particle size between 2 and 10 mm), coarse grain (particle size between 10 and 20 mm), and giant grain (particle size >20 mm).…”