Impacts of land use conflicts on riverine ecosystems

Abstract

Starting from a diagnosis of areas with different environmental land use conflicts located in various rural sub-basins of the River Sordo basin (northern Portugal), the present study analysed the ecological quality of surface water in small mountain streams to establish a relationship between land use, water and aquatic biota. Environmental land use conflicts were set up on the basis of land use and land capability maps, coded as follows: 1-agriculture, 2-pasture, 3-pasture/forest, and 4-forest. Land capability was assessed by the ruggedness number methodology (RN). The difference between the codes of capability and use defines a conflict class, where a negative or null value means no conflict and a positive value means class i conflict. Within and without the conflict areas, ecological quality of surface water was evaluated by the metrics EPT taxa, IPtI N index, diversity of Shannon-Wiener and Evenness index. Macroinvertebrate communities are strongly correlated to conflict classes, because sites without (reference sites) or with minor physicochemical and hydromorphological degradation (Class 1) presented high diversity, evenness, EPT taxa and IPtI N index, while more impacted sites (Class 2) presented an ecological status not fulfilling the demands of the European Union Water Framework Directive (2000/60). The present study indicates a significant impact of land use on water quality which has straight influence on the distribution of biota, emphasizing the key role of riparian vegetation in the conservation of aquatic ecosystems. The highest impacts on macroinvertebrate assemblages were associated with changes in water quality parameters such as temperature, oxygen saturation (%), turbidity, total suspended solids (TSS), nitrates, phosphates and sulphates, conductivity and dissolved oxygen, as well as hydromorphological alterations driven by the total absence of riparian vegetation as a consequence of terrace building, agriculture and the resectioning/reinforcement of the banks associated with the culture of vine. ms_Tables

Dominant mechanisms for the delivery of fine sediment and phosphorus to fluvial networks draining grassland dominated headwater catchments

“…The delivery of these materials to hydrological networks is augmented by the relatively low filter resistance and restricted potential for temporary storage in these small catchments. Resultantly, the catchment export of sediment and P may be closely related to the magnitude of erosion and land degradation (Kovacs et al, 2012), with adverse impacts on the aquatic habitats ensuing (Collins and Walling, 2004;Haygarth et al, 2005a;Haygarth et al, 2005b;Holden et al, 2007;Valle Junior et al, 2015).…”

Eco-hydrologic model cascades: Simulating land use and climate change impacts on hydrology, hydraulics and habitats for fish and macroinvertebrates

“…Distribution and composition of macroinvertebrates on the catchment scale are primarly affected by water quality and land use change at the catchment scale (e.g., Feld and Hering, 2007;Sundermann et al, 2013;Valle Junior et al, 2015). Increased nitrogen loads lead to an increase in biomass and productivity of primary producers.…”

The Influence of Local Land Use on the Water Quality of Urban Rivers

“…For example, [9] show how employing wetlands in an urban river system can partially remove nutrients and other elements that affect the ecosystem of a river. Likewise, [10] show that vegetation improves and maintains waterways and that sites with good riparian vegetation typically have better water qualities than those lacking riparian vegetation. Thus, monitoring and mitigation are used in combination to improve the health of urban rivers.…”