The effects of large-scale forest disturbances on hydrology – An overview with special emphasis on karst aquifer systems

Elevated Mercury Deposition, Accumulation, and Migration in a Karst Forest

“…In nonkarst forests, Hg efflux via soil erosion and runoff accounts for less than 5% of total Hg inputs, ,, except during the deforestation that causes a pulse of soil Hg erosion. ,, In this study, the high soil erosion resulting in the unusually high Hg accumulation in the low-lying land of the karst forest watershed is highlighted. The surface soil Hg concentration in the low-lying land is 4–10 times higher than the values observed in most remote/rural forest soil. , Hg transported through soil erosion increases the Hg burden to the downstream aquatic ecosystems where inorganic Hg can be transformed into highly toxic methylated Hg and then bioaccumulated and biomagnified via food chains. − In addition, the high connectivity of ground and underground water flow in the karst forest − also promotes soil Hg leaching into the groundwater and increases the risk of groundwater Hg pollution. Using the Hg isotopic tracing techniques, an earlier study has shown that Hg in groundwater was derived from the surface soil Hg leaching .…”

“…15−20 This hypothesis is based upon the heterogeneity of the rocky landscape, discontinuous vegetation covers, and soil layers 12−14 that alter the soil chemistry and atmospheric deposition spatially. In addition, the highly fragmented carbonate rock landscape is prone to erosion 13,21 and therefore accelerates soil Hg migration with runoff and leaching. 22 The complexity of the karst landscape and hydrological processes 12−14 present challenges in tracing the sources, accumulation, and migration of Hg.…”

“…The complexity of the karst landscape and hydrological processes − present challenges in tracing the sources, accumulation, and migration of Hg. To adequately capture the signal and variability of Hg cycling in this ecosystem, we increased the spatial and temporal resolution of the sampling regimes to measure process heterogeneity and identify areas of Hg hotspots (i.e., areas with elevated Hg concentrations) caused by soil Hg migration.…”

“…The karst region of southwest China is one of the three primary karst areas in the world . The relatively shallow and discontinuous soil layers, extensive rock exposure, and water leakage of karst ecosystems lead to extremely sensitive and fragile ecology. − Therefore, karst forests may exhibit a unique Hg biogeochemical cycling in contrast to other forest ecosystems. − This hypothesis is based upon the heterogeneity of the rocky landscape, discontinuous vegetation covers, and soil layers − that alter the soil chemistry and atmospheric deposition spatially. In addition, the highly fragmented carbonate rock landscape is prone to erosion , and therefore accelerates soil Hg migration with runoff and leaching …”

Effects of Soil–Rock Geomorphic Units on the Yield of Surface Runoff: A Case Study on Uncultivated Land of a Karst Area

“…Water is the key to solving the area's problems, and it is therefore important to study the processes and characteristics of water movement in karstic rocky desertification areas [29][30][31]. However, the current research on karst hydrology generally pays attention to the large scale, such as a region or watershed [32][33][34], and there are few reports on a microscale, especially on soil-rock combination microgeomorphic units, and the contribution of soil and rock to surface runoff is unclear.…”