Abstract
We analyzed the abundance of benthic algae in nine forested headwater watersheds in south-central Chile to study the relationship between the variability of the abundance of benthic algae and physicochemical parameters and forest cover factors. Between 10 November 2015 and 18 August 2016, we sampled benthic algae and physicochemical parameters in the streams and characterized forest cover factors in each of the study watersheds. We found that physicochemical parameters and forest cover factors have contrasting effects on abundance. More specifically, the following observations were made: (1) maximum diversity and abundance occurred in watersheds covered with Pinus radiata, (2) seasonal ranks did not influence the abundance of benthic algae, (3) benthic algae abundance is controlled by rank dissimilarities in type of vegetation, solar radiation, volume, density age, canopy openness, native forest area, plantation area and harvested area, and (4) regression analysis of genera exhibited significant variability with physicochemical parameters (water temperature, pH, ammonium, nitrate, phosphorus, solar radiation) and forest cover factors (volume, density, age, native forest area, plantation area and harvested area); however, these effects were not seen in all genera. Factors related to the benthic algae compartment showed the highest sensitivity to forest cover, emphasizing their value as biological indicators of water quality and stream ecological integrity.
Highlights
IntroductionHeadwater stream systems, flow patterns, temperature and substrates appear to be the key variables that influence the conditions experienced by benthic algae [1].Other more immediate impacts might be related to flow patterns (via terrain slope and roughness), temperature (via elevation and climate-dependent riparian vegetation), the geological environment and land use [2,3]
At a local scale, headwater stream systems, flow patterns, temperature and substrates appear to be the key variables that influence the conditions experienced by benthic algae [1].Other more immediate impacts might be related to flow patterns, temperature, the geological environment and land use [2,3]
The present study focuses on the relationships between forest cover, riparian vegetation, and streams to determine benthic algae composition and their variation under different forest cover schemes and conditions in the watershed headwaters
Summary
Headwater stream systems, flow patterns, temperature and substrates appear to be the key variables that influence the conditions experienced by benthic algae [1].Other more immediate impacts might be related to flow patterns (via terrain slope and roughness), temperature (via elevation and climate-dependent riparian vegetation), the geological environment and land use [2,3]. The availability of light and the productivity of streams act as controlling factors for the composition of benthic algae at various riparian vegetation widths [4,5]. These conditions directly influence the streams’ habitats and can be used to predict species composition [1]. The composition of benthic algae can be related to water chemistry (pH, stream conductivity and nutrient concentrations), and factors such as substrate, light availability, and flow velocity [7,8,9,10]
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