Effects of Oil Palm Plantations on the Habitat Structure and Biota of Streams in Eastern Amazon

Abstract

Oil palm plantations have expanded around the world, increasing concern about its pressure on deforestation rates and the homogenization of the landscape. In this context, the present study aimed to evaluate the impact of oil palm plantations on the physical characteristics of streams in Amazonia and their effects on Heteroptera, Odonata and Fish assemblages. A total of 23 streams were sampled, eight within fragments of primary forest, while 15 were in oil palm plantations. Data were collected on characteristics of the channel morphology, substrate, hydraulics, instream cover for aquatic organisms, riparian vegetation, human impacts and woody debris. Instream cover and proximity of human impacts were the variables that had the greatest effects on the physical structure of the streams, showing variation between streams of forest in pristine areas and oil palm plantations. Of the analyzed parameters, substrate, instream cover and woody debris influence the richness of Heteroptera, Odonata and Fish. The impact of oil palm plantations on local streams depended on the size of the plantations, and they cannot be considered an adequate substitute for lost habitats in efforts to preserve the physical habitat of Amazonian streams. Any type of conversion of the natural forest can have direct or indirect impacts on the dynamics and structure of these environments, with potentially negative consequences for their biodiversity. The maintenance of an adequate buffer zone of native riparian vegetation adjacent to the streams that flow through the plantations recommended, because this appears to be the principal factor determining the physical conditions of these streams.

To what extent can oil palm plantations in the Amazon support assemblages of Odonata larvae?

“…The results of this study are in agreement with other studies that show turnover as the main pattern for aquatic insect assemblages, as they are highly influenced by spatial processes that can restrain their dispersal (Lujan et al ., ; Rouquette et al ., ). The different turnover patterns observed can be related to Anisoptera and Zygoptera dispersals and their relation to environmental heterogeneity and variations in the hydrological system (Mendes et al ., , ; Juen et al ., ). Generally, Anisoptera have a high dispersal ability in a short period of time (Corbet, ), which allows them to occupy a greater proportion of suitable niches at local and regional scales (De Marco & Latini, ).…”

“…Studies in streams of oil palm areas without riparian forests showed loss of macroinvertebrate diversity (Luke et al ., 2017b). However, in studies on streams with riparian vegetation in oil palm plantation areas, a similar macroinvertebrate diversity was observed between oil palm and forested areas, which indicates the importance of the presence and maintenance of riparian vegetation as a buffer zone for the effects caused by plantations (Cunha et al ., ; Juen et al ., ; Carvalho et al ., ).…”

“…In Brazil, the Forest Code – Law 4.771/65 – determines that water bodies in plantation areas must maintain forested buffers, which are called Permanent Preservation Areas (PPAs). The removal or reduction of riparian buffers can lead to a reduction in the types of substrate and in the number of aquatic organisms in the Amazon's streams (Juen et al ., ; Carvalho et al ., ). Among these problems is the reduction or removal of riparian vegetation surrounding aquatic environments (e.g.…”

“…Odonata have been used as model organisms to detect environmental changes in oil palm areas because they are highly affected by water quality and they inhabit a range of different microhabitats during their life cycles (Juen et al ., ; Luke et al ., 2017a; Carvalho et al ., ). Odonata have hemimetabolous development, with an aquatic larval stage and terrestrial adult stage.…”

Land cover, riparian zones and instream habitat influence stream fish assemblages in the eastern Amazon

“…Presently, oil palm production is the main crop, but interest in sugarcane is increasing. Some of the sites sampled in this study were surveyed in previous studies (Benone et al, 2017;Ferreira, Begot, Prudente, Juen, & Montag, 2018;Juen et al, 2016;Prudente, Pompeu, & Montag, 2018;Prudente et al, 2017). Within our study region, conventional logging started in the 1970s, oil palm has been cultivated since the 1980s, and reducedimpact logging was established in 2000 under guidelines proposed by the mandatory forest management plan of the Brazilian Forest Code (Law 4.771/65;Brasil, 1965).…”