Succession of algal communities in headwaters: a comparison of pine afforested and natural grassland streams

Abstract

We evaluated changes in the succession process in benthic algal communities of an afforested stream by comparing them with those in a grassland stream through analysis of temporal changes in composition, structure and functional traits in a 3-month experiment. We hypothesized that sunlight intensity reduction as a result of streamside implanted tree shading reduces the succession rate and community physiognomic complexity. We selected two streams with different riparian cover (grassland and pine afforestation) for installation of unglazed tiles as artificial substrates. The tiles were collected from each stream after 23, 45 and 73 days of exposure. Afforestation produced changes in algal succession, with lower biomass, lower diversity at the beginning of the experiment, and an increase in the proportion of small, low-profile, tolerant, unicellular and stalked algae, coinciding with the predominance of Achnanthidium. However, the grassland stream contained a higher proportion of intermediate-size algae, as well as a larger proportion of high-profile algae, coinciding with the expected results. In the afforested stream, succession proceeded toward the dominance of low-profile species, that were tolerant of low-light conditions. However, in grassland streams with higher sunlight availability, high-profile algae prevailed without the displacement of tolerant forms. Overall, our results indicate that algal communities in afforested stream remain structurally simpler.

Disentangling grazing and light controls on algal communities in grassland and afforested streams

“…Community composition showed differences with time in both streams, similar to the reported by Cibils‐Martina, Principe, et al (), but multivariate analysis allowed detecting differences between grazed and ungrazed substrates only in the afforested stream. This result is contrary to our prediction and to the findings of other authors (Cibils Martina et al, ; Steinman et al, ; Wellnitz & Rader, ; Wellnitz & Ward, ) that reported higher grazing effects on substrates exposed to higher light intensity, which favours the development of more productive algal communities.…”

“…In the afforested stream, algal biomass (Chl a and AFDM) did not increase with time, suggesting growth limitation by light (Cibils‐Martina, Principe, et al, ; Stevenson, ). Cibils‐Martina, Principe, et al () also found that succession trajectories were different between grassland and afforested streams, with a longer accrual phase occurring in grassland streams and lower algal biomass in afforested streams. As we expected, in this stream, there were no important differences between grazed and ungrazed substrates in structural or functional attributes.…”

“…However, filamentous forms and high proportions of mucilage, which may be abundant in high light conditions, are difficult to graze (Wellnitz & Ward, ). Cibils‐Martina, Principe, Márquez, Gari, and Albariño () found that in an afforested stream, succession proceeded toward the dominance of prostrate, low‐profile species, tolerant of low‐light conditions. However, in grassland streams with higher sunlight availability, high‐profile algae prevailed.…”

Expanding the trait-based concept of benthic diatoms: Development of trait- and species-based indices for conductivity as the master variable of ecological status in continental saline lakes

“…simple community structure (Cibils-Martina et al, 2017); similarly to communities of soda pans. Motile species with small cell size (S1) might hide easily among inorganic particles of mud in the drying period of lakes; similarly to cases observed in sedimanteted, drying streams (Lange et al 2016).…”

Trait structure and functional diversity of periphytic algae in a floodplain conservation area

“…The knowledge of the temporal and spatial dynamics of functional strategies of periphytic algae contributes to predicting, generalizing and understanding processes structuring these communities (Dunck et al 2013;Cibils et al 2015;Cibils-Martina et al 2017). Because they have a sessile life style (for the most part) and short life cycle, periphytic algae respond rapidly to environmental changes and are directly influenced by environmental alterations in temperature, water velocity, light and nutrient availability (Biggs 1996;Stevenson 1996;Bourassa and Cattaneo 2000;Moresco et al 2009;Ferragut and Bicudo 2010;Lange et al 2011;Larson and Passy 2012;Algarte et al 2013;Dunck et al 2013;Moresco and Rodrigues 2013;Rodrigues et al 2013;Zanon et al 2013).…”