Water erosion risk prediction in eucalyptus plantations

Abstract

Eucalyptus plantations are normally found in vulnerable ecosystems such as steep slope, soil with low natural fertility and lands that were degraded by agriculture. The objective of this study was to obtain Universal Soil Loss Equation (USLE) factors and use them to estimate water erosion risk in regions with eucalyptus planted. The USLE factors were obtained in field plots under natural rainfall in the Rio Doce Basin, MG, Brazil, and the model applied to assess erosion risk using USLE in a Geographic Information System. The study area showed rainfall-runoff erosivity values from 10,721 to 10,642 MJ mm ha-1 h-1 yr-1. Some soils (Latosols) had very low erodibility values (2.0 x 10-4 and 1.0 x 10-4t h MJ-1 mm-1), the topographic factor ranged from 0.03 to 10.57 and crop and management factor values obtained for native forest, eucalyptus and planted pasture were 0.09, 0.12 and 0.22, respectively. Water erosion risk estimates for current land use indicated that the areas where should receive more attention were mainly areas with greater topographic factors and those with Cambisols. Planning of forestry activities in this region should consider implementation of other conservation practices beyond those already used, reducing areas with a greater risk of soil erosion and increasing areas with very low risk.

Soil Disturbance Effects from Tethered Forwarding on Steep Slopes in Brazilian Eucalyptus Plantations

“…This resulted in a median erosion rate of 4.3 Mg/ha/year and maximum of 10.1 Mg/ha/year. These values are much more comparable to the aforementioned tolerances and lower-impact operations such as cable yarding [2,35,83,85]. This illustrates the difference adequate soil cover makes in predicted erosion rates, especially on such extreme slopes.…”

“…The low slope class had a K value of 0.063 t h MJ −1 mm −1 , the medium slope class had K values from 0.091 to 0.146 t h MJ −1 mm −1 , and the high Slope class contained K values from 0.157 to 0.237 t h MJ −1 mm −1 . The topographic factor (LS) is a function of slope steepness and slope length; thus, the observed LS values were high compared with other studies on more gentle terrain [85]. Our study areas were characterized by steep, long, continuous slopes.…”

“…Another reason predicted erosion rates were high could be the inadequacy of the USLE for estimating erosion on extremely steep slopes. Few studies have used the USLE on such extreme slopes; most only have used it up to 16-27 degrees [33,[85][86][87][88]. The USLE was designed for use on relatively gentle terrain, such as agricultural lands [89].…”

Use of Usle/ Gis Technology for Identifying Criteria for Monitoring Soil Erosion Losses in Agricultural Areas

“…Lastly, we should highlight the occurrence of erosion in areas under silviculture, especially where the soil is exposed and during the rainy season. These results confirm the findings of Silva et al (2014). Therefore, the planning of forest activities in this watershed should include the implementation of other conservation practices, in addition to those already used, to eliminate exposed areas containing Cambisols, and forestry should be introduced.…”

“…Therefore, the weight of the factors land use, soil management, and conservation practices in these biomes does not seem enough to reduce the natural risk of erosion in this sub-watershed, especially because of the undulating relief in Cambisols (which are considered young and shallow) with native and cultivated pastures, as reported by Oliveira et al (2014). Furthermore, according to Silva et al (2014), the estimated risk of water erosion indicated that areas with higher LS and Cambisols should receive more attention. (Source: *Carvalho, 2008) Although the area of the Samambaia River subwatershed is four times larger than the Arrasta-Burro tributary sub-watershed, mean A values were similar in these two areas (39 ± 97 t ha -1 year -1 and 38 ± 87 t ha -1 year -1 , respectively), indicating that land use and occupation was similar in these sub-watersheds.…”