The Buffer Capacity of Riparian Vegetation to Control Water Quality in Anthropogenic Catchments from a Legally Protected Area: A Critical View over the Brazilian New Forest Code

Abstract

The riparian buffer width on watersheds has been modified over the last decades. The human settlements heavily used and have significantly altered those areas, for farming, urbanization, recreation and other functions. In order to protect freshwater ecosystems, riparian areas have recently assumed world recognition and considered valuable areas for the conservation of nature and biodiversity, protected by forest laws and policies as permanent preservation areas. The objective of this work was to compare parameters from riparian areas related to a natural watercourse less than 10 m wide, for specific purposes in Law No. 4761/65, now revoked and replaced by Law No. 12651/12, known as the New Forest Code. The effects of 15, 30 and 50 m wide riparian forest in water and soil of three headwater catchments used for sugar cane production were analyzed. The catchments are located in the Environmental Protection Area of Uberaba River Basin (state of Minas Gerais, Brazil), legally protected for conservation of water resources and native vegetation. A field survey was carried out in the catchments for verification of land uses, while periodical campaigns were conducted for monthly water sampling and seasonal soil sampling within the studied riparian buffers. The physico-chemical parameters of water were handled by ANOVA (Tukey’s mean test) for recognition of differences among catchments, while thematic maps were elaborated in a geographic information system for illustration purposes. The results suggested that the 10, 30 or even 50 m wide riparian buffers are not able to fulfill the environmental function of preserving water resources, and therefore are incapable to ensure the well-being of human populations. Therefore, the limits imposed by the actual Brazilian Forest Code should be enlarged substantially.

A Regression Model of Stream Water Quality Based on Interactions between Landscape Composition and Riparian Buffer Width in Small Catchments

“…In the second case, there are two rules: The transition rule takes into account the size of land property calculated as fiscal modules and creates a distance from the stream margin that goes from a minimum of 5 m to a maximum of 20 m, considering the regular river bank; the permanent rule defines 30 m as unique distance. This study reinforces the suggestion of Valera et al [15], who alerted that a 30 m buffer strip width, as proposed in the New Forest Code, is barely capable of protecting water quality in the EPA-MURB. The discussion on buffer strips, their geometry and composition, optimal widths, cost-benefit analysis for implementation [82][83][84][85], among other topics, is still a matter of debate.…”

“…Values larger than 10 mm day-1 are represented in boldface. Source: Valera et al [15]. The measurement of water quality parameters in every campaign involved 10 repetitions, as recommended in the CONAMA's Resolution No.…”

“…A key parameter of riparian buffers is the width. Several studies refer minimum thresholds for riparian buffer width [13], while in some countries, such as Brazil or the United States, this width has been legally imposed or recommended [14,15]. However, other studies consider fixed-width recommendations problematic because riparian ecological responses are highly variable [8], and hence, optimal buffer widths are expected to vary from site to site [13].…”

Permanent preservation areas in Mantiqueira sierra: perspectives for regularization along watercourses

“…Due to spatial resolution limitation, polyline vector files have been used to outline both PPA and recovery areas, since we do not have geographic information to spatialize watercourses widths. Although unconventional, polyline vector files have been reported in literature as a suitable technique to simulate PPA limits (Alvarenga et al, 2017;Rosot et al, 2018;Rodríguez-Romero et al, 2018;Valera et al, 2019).…”

The Influence of Riparian Corridor Land Use on the Pesquería River’s Macroinvertebrate Community (N.E. Mexico)

“…All these metrics Next, 16 sampling sites (each 100 m long) were strategically selected along 180 km of the PR's main channel, which included the headwaters of the river and sites before or after human settlements or agricultural areas. Then, the land use proportion for the riparian area of each sampling site was calculated, taking into consideration a 50 m (width) buffer zone along both sides of the channel upstream of each site ( Figure 1) [46][47][48]. Furthermore, we measured the distance from headwaters (DFH) of each sampling site to see if the macroinvertebrate community was influenced by the land use or by the longitudinal natural variability of river conditions (i.e., the river continuum concept) [49,50].…”