Abstract
This investigation aimed to describe a short term (70 days) ecological succession event of a macroalgal community in a stream from northwestern São Paulo state (20º43'S; 49º13'W) after artificial disturbance (removal); evaluate if community structure characteristics were similar before and after the experimental period; compare the successional process of two experimental stream segments (partly and completely disturbed segments, PDS and CDS, respectively), simulating medium (partial) and high impact (complete removal) disturbances. In terms of colonization time, Oedogonium sp. was classified as successionally indifferent, whereas Chaetophora elegans (Roth) C. Agarth and Batrachospermum delicatulum (Skuja) Necchi et Entwisle were classified as late successional forms for CDS; for PDS the only difference was that Oedogonium sp. was classified as late successional. In terms of successional strategy, Oedogonium sp. was classified as a C-S strategist, whereas C. elegans and B. delicatulum were regarded as S strategists for both stream segments. Temperature was the most influential variable for most species and biological variables, with temperature increases probably favouring reproduction rates. In general, community structure recovery was not complete at the end of succession. This short-term study was consistent with the deterministic process of succession, since the succession trajectory was predictable, because species richness and abundance, growth forms and life strategies followed a definite pattern.
Highlights
Succession is the process that animal and plant communities undergo leading to a final stage, which is usually recognized by its stability and clear environmental relationship in a regional scale (Dawson et al 1978)
It is interesting to notice a slight increase in current velocity measured before the experiment and after removal of the macroalgal community from 38.0 to 43.9 cm.s-1 at completely disturbed segment (CDS) and from 40 to 43 cm.s-1 at partially disturbed segment (PDS) (Fig. 2)
Among the macroalgal species present during the short-term sucessional process of the study stream: C. elegans and B. delicatulum were classified as later successional species, according to the criteria of McCormick & Stevenson (1991)
Summary
Succession is the process that animal and plant communities undergo leading to a final stage (climax), which is usually recognized by its stability and clear environmental relationship in a regional scale (Dawson et al 1978). Connell & Slatyer’s (1977) model is one of the best known theoretical systems for the study of the succession process According to those authors, the succession mechanisms can be incorporated in three models: 1) facilitation, that corresponds to the Clementesian model of floristic substitution (Egler 1954), in which early successional species modify the environment and facilitate the appearance of late successional species; 2) inhibition, which states that the initial invaders (Egler 1954), regulate the succession. According to Biggs et al (1998) the physical environment is the filter to the development of specific characteristics during the evolution time, which can be better analyzed and understood by separating the environment in different combinations imposed by the primary and secondary variables (frequency of disturbance events and resource supplies, respectively) They stated that the different periphytic taxa have developed specialized characteristics that enable them to explore one or several sectors of a habitat matrix. Species life strategies were divided into four different kinds: competitive strategy (C), represented by species that are able to grow well in habitats stable and rich in nutrients (eutrophic); strategy C-S, with species more adapted to stable habitats and moderate nutrient concentrations (mesotrophic); stresstolerant strategy (S), that involves species well adapted to stable habitats, but with low nutrient concentrations (oligotrophic); and the ruderal strategy (R), including species that are adapted to environments moderately or highly disturbed and with variable nutrient supply
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
