The Influence of Different Forest Characteristics on Non-point Source Pollution: A Case Study at Chaohu Basin, China.

Hao Cheng,Chen Lin,Chenxi Zhu,Lingyun Peng,Liangjie Wang,Junfeng Xiong

doi:10.3390/ijerph17051790

Abstract

Forestland is a key land use/land cover (LULC) type that affects nonpoint source (NPS) pollution, and has great impacts on the spatiotemporal features of watershed NPS pollution. In this study, the forestland characteristics of the Chaohu Basin, China, were quantitatively represented using forestland types (FLTs), watershed forest coverage (WFC) and forest distance from the river (DFR). To clarify the impact of forests on NPS pollution, the relationship between forestland characteristics and watershed nutrient outputs (TN and TP) was explored on a monthly scale using SWAT (Soil and Water Assessment Tool) and the period simulation was 2008–2016. The results showed that: (1) the TN and TP showed similar output characteristics and the rainy season was the peak period of nitrogen and phosphorus output. (2) Among the forestland characteristics of forestland types, watershed forest coverage and forest distance from the river, watershed forest coverage and forest distance from the river had greater effects than forestland types on the control of watershed nutrient outputs (TN and TP). (3) In different forestland types, the watershed nutrient outputs intensity remained at the lowest level when the FLTs was mixed forest, with a TN output of 1244.73kg/km2 and TP output of 341.39 kg/km2. (4) The watershed nutrient outputs and watershed forest coverage were negatively correlated, with the highest watershed forest coverage (over 75%) reducing the TN outputs by 56.69% and the TP outputs by 53.46% compared to the lowest watershed forest coverage (below 25%), it showed that in areas with high forest land coverage, the non-point source pollution load in the watershed is smaller than in other areas. (5) forest distance from the river had an uncertain effect on the TN and TP output of the basin, the forestland itself is a source of pollution, but it also has the function of intercepting pollution movement; the forest distance from the river in the range of 500–1000 m had the lowest NPS pollution. Considering the different forest characteristics and topographical factors, an optimal allocation mode of differentiated forest land was proposed, these suggestions will provide a scheme for surface source pollution prevention and control in the basin. This research gap is the basis of real forestland optimization. We may optimize the forestland layout for NPS pollution prevention and control by clarifying the internal mechanism.

Highlights

Nonpoint source (NPS) pollution is a major environmental problem that seriously affects residents’living conditions and economic development because it is nonspecific and difficult to identify and collect
25%), it showed that in areas with high forest land coverage, the non-point source pollution load in the watershed is smaller than in other areas. (5) forest distance from the river had an uncertain effect on the TN and TP output of the basin, the forestland itself is a source of pollution, but it has the function of intercepting pollution movement; the forest distance from the river in the range of 500–1000 m had the lowest NPS pollution
Our research focused on the control of NPS pollution by different forestland characteristics

Summary

Introduction

Nonpoint source (NPS) pollution is a major environmental problem that seriously affects residents’living conditions and economic development because it is nonspecific and difficult to identify and collect. It has become a great threat to water quality and aquatic ecosystem restoration [1]. Nitrogen and phosphorus pollution account for more than 50% of the pollution load of receiving water body such as. Taihu Lake and Chaohu Lake [2,3,4], and these pollutants have a serious impact on receiving water bodies according to previous studies, causing deterioration of water quality and eutrophication of water bodies [5,6,7,8]. Controlling NPS pollution is a crucial way to alleviate water pollution [9,10,11,12]. Human activity is a key element in the loss of nitrogen and phosphorus in basins [10,13,14,15]

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