scholarly journals Past and present land use influences on tropical riparian zones: an isotopic assessment with implications for riparian forest width determination

2016 ◽  
Vol 16 (2) ◽  
Author(s):  
Luiz Felippe Salemi ◽  
Silvia Rafaela Machado Lins ◽  
Elizabethe de Campos Ravagnani ◽  
Marcelo Magioli ◽  
Melissa Gaste Martinez ◽  
...  

Abstract In this article, by using carbon stable isotopes, we assessed the past and present land use influences that riparian areas are subject within agricultural landscapes. Emphasis is given to the understanding of the effects of the 2012 Brazilian Forest Act on such areas. We selected five riparian areas within a highly C4 dominated agricultural landscape. Three of them had 30 meters native riparian forest buffer (NRFB) and two of them had 8 meter and no NRFB. We used three 100 meter-transects located 5, 15 and 30 meters relative to stream channel to obtain soil samples (0 - 10 cm). All riparian areas presented soil carbon isotopic signatures that are not C3 (native forests) irrespective of having or not 30 meters NRFB. Two cases presenting less than 30 meters NRFB had higher C4 derived carbon contribution. All of the other three areas that followed the 30 meters NRFB presented, to some degree, C4 derived carbon, which was attributed to C4 organic matter deposition originated from cultivated areas and, in one case, to the persistence of former exotic grasses. With the 2012 Forest Act allowing narrower buffers (< 30 meters), we expect C4 contributions to soil organic matter to remain high in riparian areas and streams within agricultural landscapes dominated by C4 plants where 30 meter NRFB is no longer required. Such contributions will likely continue to have detrimental effects on stream water quality and biota.

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 390 ◽  
Author(s):  
Higo Dalmagro ◽  
Michael Lathuillière ◽  
Fernando Sallo ◽  
Maurel Guerreiro ◽  
Osvaldo Pinto ◽  
...  

Forest to pasture land use change following deforestation in Southern Amazonia can result in changes to stream water quality. However, some pasture streams have riparian forest buffers, while others are dammed for farm ponds. Stream corridor management can have differential effects on hydrology and dissolved organic matter (DOM) characteristics. We examined rainfall-runoff patterns and DOM characteristics in a pasture catchment with a forested riparian buffer, and an adjacent catchment with an impoundment. Total streamflow was 1.5 times higher with the riparian buffer, whereas stormflow represented 20% of total discharge for the dammed stream versus 13% with buffer. Stream corridor management was also the primary factor related to DOM characteristics. In the impounded catchment, DOM was found to be less structurally complex, with lower molecular weight compounds, a lesser degree of humification, and a larger proportion of protein-like DOM. In the catchment with a forested buffer, DOM was dominated by humic-like components, with fluorescence characteristics indicative of DOM derived from humified soil organic matter under native vegetation. Our results suggest that differences in stream corridor management can have important implications for carbon cycling in headwater pasture catchments, and that such changes may have the potential to influence water quality downstream in the Amazon basin.


2015 ◽  
Vol 21 (1) ◽  
pp. 60 ◽  
Author(s):  
Anita F. Keir ◽  
Richard G. Pearson ◽  
Robert A. Congdon

Remnant habitat patches in agricultural landscapes can contribute substantially to wildlife conservation. Understanding the main habitat variables that influence wildlife is important if these remnants are to be appropriately managed. We investigated relationships between the bird assemblages and characteristics of remnant riparian forest at 27 sites among sugarcane fields in the Queensland Wet Tropics bioregion. Sites within the remnant riparian zone had distinctly different bird assemblages from those of the forest, but provided habitat for many forest and generalist species. Width of the riparian vegetation and distance from source forest were the most important factors in explaining the bird assemblages in these remnant ribbons of vegetation. Gradual changes in assemblage composition occurred with increasing distance from source forest, with species of rainforest and dense vegetation being replaced by species of more open habitats, although increasing distance was confounded by decreasing riparian width. Species richness increased with width of the riparian zone, with high richness at the wide sites due to a mixture of open-habitat species typical of narrower sites and rainforest species typical of sites within intact forest, as a result of the greater similarity in vegetation characteristics between wide sites and the forest proper. The results demonstrate the habitat value for birds of remnant riparian vegetation in an agricultural landscape, supporting edge and open vegetation species with even narrow widths, but requiring substantial width (>90 m) to support specialists of the closed forest, the dominant original vegetation of the area.


2021 ◽  
Vol 109 ◽  
pp. 105679
Author(s):  
António Carlos Pinheiro Fernandes ◽  
Lisa Maria de Oliveira Martins ◽  
Fernando António Leal Pacheco ◽  
Luís Filipe Sanches Fernandes

2006 ◽  
Vol 174 (1-4) ◽  
pp. 161-179 ◽  
Author(s):  
T. Tsegaye ◽  
D. Sheppard ◽  
K. R. Islam ◽  
W. Tadesse ◽  
A. Atalay ◽  
...  

2006 ◽  
Vol 35 (2) ◽  
pp. 617-627 ◽  
Author(s):  
A. Hayakawa ◽  
M. Shimizu ◽  
K. P. Woli ◽  
K. Kuramochi ◽  
R. Hatano

2020 ◽  
Vol 12 (14) ◽  
pp. 5500 ◽  
Author(s):  
Yu Song ◽  
Xiaodong Song ◽  
Guofan Shao

Intense human activities and drastic land use changes in rapidly urbanized areas may cause serious water quality degradation. In this study, we explored the effects of land use on water quality from a landscape perspective. We took a rapidly urbanized area in Hangzhou City, China, as a case study, and collected stream water quality data and algae biomass in a field campaign. The results showed that built-up lands had negative effects on water quality and were the primary cause of stream water pollution. The concentration of total phosphorus significantly correlated with the areas of residential, industrial, road, and urban greenspace, and the concentration of chlorophyll a also significantly correlated with the areas of these land uses, except residential land. At a landscape level, the correlation analysis showed that the landscape indices, e.g., dominance, shape complexity, fragmentation, aggregation, and diversity, all had significant correlations with water quality parameters. From the perspective of land use, the redundancy analysis results showed that the percentages of variation in water quality explained by the built-up, forest and wetland, cropland, and bareland decreased in turn. The spatial composition of the built-up lands was the main factor causing stream water pollution, while the shape complexities of the forest and wetland patches were negatively correlated with stream water pollution.


<em>Abstract.</em>—Ecologists recognize that surrounding land use can influence the structure and function of aquatic ecosystems, but few studies have explicitly examined the relative effects of different types of land use on stream ecosystems. We quantified the relationships between different land uses (forested, urban, agricultural with or without riparian buffers) and stream physicochemical variables and resident fish assemblages in 21 southwestern Michigan streams. These streams were located within a single basin (Kalamazoo River) and ecoregion to minimize differences in natural landscape conditions. Streams responded to a gradient of land use, with forested streams having the least degraded water quality, physical habitat, and fish assemblages, and agricultural streams lacking buffers being the most degraded. Urban and agricultural streams with buffers displayed characteristics intermediate to forested and agricultural streams lacking buffers. In general, habitat complexity and water quality declined across this land-use gradient from forested to agricultural streams, whereas fish density, richness, and dominance by tolerant species increased along the land-use gradient. Although urban streams had lower percentages of altered land use (i.e., <40% urban) in their catchments compared to agricultural streams (i.e., >50% agriculture), both land uses appeared to have similar detrimental effects on streams suggesting higher per unit area impacts of urbanization on streams. The presence of forested riparian buffers along agricultural streams increased the complexity of instream habitat, but resulted in few benefits to fish assemblages, suggesting that stream water quality in altered landscapes may be constraining fish assemblages more than physical habitat.


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