Impacts of artificial reservoirs on floristic diversity and plant functional traits in dry forests after 15 years.

Sf Lopes,I Schiavini,Vs Vale,Ja Prado Júnior

doi:10.1590/1519-6984.16013

Abstract

Dams are of paramount importance to a wide variety of human services and many of their environmental problems are known; however, there are few studies in the world addressing the impacts on the native vegetation previously distant from water bodies which became close to the lakeshore created by a dam. Thus, this paper aims to analyze the responses of a dry forest to a dam after 15 years. For this, 20 random samples of 40 trees were made, 10 close to the lakeshore and 10 distant from it, by applying the central square point method. Close to the dam, we found higher values regarding basal area, number of trees, number of evergreen trees, and zoochoric syndrome, but there were lower values of Shannon's diversity index. Therefore, the impacts of the dam after 15 years caused several changes to the tree community. The greater basal area close to the dam suggests that water deficit during the dry season was decreased and plants have thicker trunks. On the other hand, this sector had much more zoochoric syndrome and a larger number of evergreen trees than plots which are distant from water, suggesting changes with regard to the community's ecological functions. Furthermore, structural floristic data shows that the sector close to the dam is less similar to other deciduous forests within the same geographical region than the sector distant from water, thus providing evidence of the impacts of dams on the tree community.

Highlights

Dams have facilitated human life; at first, with regard to farming, transportation, and domestic services and, currently, they are built to generate hydroelectric power (Evans et al, 2009)
Shannon’s diversity in sector A (3.40) was significantly higher than that in the sector B (3.20) (Table 2); otherwise, the basal area and the number of individuals were significantly lower in sector A (23.32 m2.ha–1 and 1,542 ind.ha–1) than in sector B (34.43 m2.ha–1 and 2,672 ind.ha–1) (Table 2)
We found significant differences both in the dispersal mechanism and leaf deciduousness

Summary

Introduction

Dams have facilitated human life; at first, with regard to farming, transportation, and domestic services and, currently, they are built to generate hydroelectric power (Evans et al, 2009). This kind of power is regarded as a clean and cheap alternative, accounting for 16% of the worldwide electricity generation in 2005 (Evans et al, 2009). At least 45,000 dams > 15 m high obstruct 60% of the fresh water flowing into the oceans (Nilsson et al, 2005). The native vegetation previously distant from water bodies which became close to the lakeshore created by a dam represents long-term consequences, because this new “riparian vegetation” is completely distinct from an original riparian environment with regard to species and characteristics

Objectives

Methods

Results

Conclusion