Impacts of gap planting on soil density and erosion

Abstract

By 2016, there were 32.70 million ha of degraded forests in Indonesia. If it is not quickly rehabilitated, there will be land use changes and expansion of industrial forest plantation, which significantly affects its biodiversity and environmental. This research aims to study the impacts of the gap planting technique with red jabon on soil density and erosion. The research used: (1) the gap planting technique of red jabon with a proportion of the total gap area to the total natural forest area of 40%: 60%, planting distance of 4m x 5m, and the number of trees planted of 200 stems/ha, (2) Digital-Humboldt Static Cone Penetrometer to measure soil density, and (3) stick for soil erosion measurement. The results showed that gap planting with red jabon to rehabilitate degraded natural forests increased the soil density, but its value was categorized as a very loose soil class. On the other hand, the soil erosion in gap area was lower than in degraded natural forest area, because the condition of a part of the degraded forest was unvegetated land, and there were the wastes of branches, twigs, and leaves as well as grown grasses on the soil surface that hinder the soil erosion in the gap area. This research concluded, that the impact of the gap planting on soil density can be neglected, and the impact of the gap planting on soil erosion is positive. Further research on social-economic, biodiversity, effective and efficiency aspects of the gap planting technique for forest rehabilitation are needed before its implementation.

Plant diversity on coffee agroforestry land in the buffer zone of Bromo Tengger Semeru National Park in East Java, Indonesia

“…Plants from the Fabales order may improve soil fertility through nitrogen fixation. On the other hand, plants from the Caryophyllales order could protect against erosion and increase soil resistance to disturbances of temperature and drought (Elias and Suwarna 2019).…”

Combating Desertification through Enhancement of Woody Floral Diversity in the Drylands of Kenya: Analysis, Milestones, and Strategies

“…Furthermore, the use of logged-over gaps for enrichment planting was recommended given the difficulty to maintain constant line width and even light condition, the cost of annual clean operation, and the rigid geometric patterns of planting lines [50]. In Indonesia, gap planting with Anthocephalus macrophyllus to rehabilitate degraded natural forests increased soil density, although its value was categorized as a very loose soil class [51]. In another study from Malaysia, the total mean microbial enzymatic activity, as well as biomass carbon (C) and nitrogen (N) content, was significantly higher under enrichment planting than under secondary forest [46].…”

Does Gap Opening and Planting to Rehabilitate the Degraded Tropical Natural Forests Affect the Forest Composition and Structure?

“…In line with this theory, the research results of Long et al (2018) showed that the management of Engelmann spruce in Intermountain West used a small group selection cutting system, which is preferred because it mimics the dynamics of the gap phase. Furthermore, some research on gap opening and planting for rehabilitation of degraded natural forests in Indonesia dan Brazil showed that the cultivation of local superior intolerant tree species using gap opening and planting is more costeffective and needs shorter-term investment (Grogan et al, 2013;Schwartz et al, 2017;Elias & Suwarna, 2019). Elias and Suwarna (2019) mentioned, that the application of gap opening and planting did not harm the environment in terms of open areas, soil erosion, soil compaction, and forest fire risk aspects.…”

“…Furthermore, some research on gap opening and planting for rehabilitation of degraded natural forests in Indonesia dan Brazil showed that the cultivation of local superior intolerant tree species using gap opening and planting is more costeffective and needs shorter-term investment (Grogan et al, 2013;Schwartz et al, 2017;Elias & Suwarna, 2019). Elias and Suwarna (2019) mentioned, that the application of gap opening and planting did not harm the environment in terms of open areas, soil erosion, soil compaction, and forest fire risk aspects. On the contrary, it showed positive impacts such as cost-effectiveness, job creation for local communities, and a productivity increase in rehabilitated forests.…”