Physicochemical Properties as Driver of Odonata Diversity in Oil Palm Waterways

Muhamad Ishak,Ahmad R Norhisham,Amal Ghazali,Stephen M Thomas,Siti Nurhidayu,Badrul Azhar

doi:10.3389/ffgc.2021.613064

Abstract

Large-scale oil palm agriculture has caused deforestation in the tropics, but also degrades stream water quality and reduces aquatic biodiversity. Though the outcomes of industrial-scale oil palm plantations for biodiversity have been explored extensively, the consequences of small-scale oil palm agriculture for freshwater macroinvertebrate fauna are poorly understood. Here, we explored the impacts of small-scale oil palm agriculture on aerial adult Odonata (the dragonflies and damselflies), which, due to their inherent sensitivity to habitat degradation, represent useful indicators of wider ecosystem health. We surveyed riparian corridors of man-made waterways in natural habitats converted into agricultural lands in both peat swamp and mangrove forest, comprising a total of 60 sampling units across a region of Peninsular Malaysia where such small-scale agricultural practices are widespread. We hypothesized that physicochemical water quality of oil palm waterways together with riparian vegetation influence Odonata species richness and composition. Our results revealed that Odonata species richness increased with dissolved oxygen, water temperature and vegetation cover, but decreased with water level, pH, and total dissolved solids. Species composition was influenced by both dissolved oxygen and pH. The present study provides valuable insights into the effects of small-scale oil palm agriculture for water quality of associated aquatic habitats, and subsequent responses of adult Odonata. Therefore, smallholders should reduce the use of chemical pesticides and fertilizers to improve the conservation value of oil palm waterways for both Odonata and aquatic fauna more generally, in order to be certified as biodiversity-friendly agriculture.

Highlights

Forest conversion to agricultural lands poses a major threat to biodiversity across terrestrial and aquatic ecosystems at multiple spatial scales (Mercer et al, 2014; Oliveira-Junior et al, 2015; Ghazali et al, 2016; Asmah et al, 2017)
Our results revealed no significant difference in Odonata species richness (t = −1.07; p = 0.285) between peat swamp forest-converted and mangrove forest-converted smallholdings
Our data suggests that adult odonates have highly specific habitat requirements with respect to physicochemical water quality of oil palm waterways and riparian vegetation

Summary

Introduction

Forest conversion to agricultural lands poses a major threat to biodiversity across terrestrial and aquatic ecosystems at multiple spatial scales (Mercer et al, 2014; Oliveira-Junior et al, 2015; Ghazali et al, 2016; Asmah et al, 2017). Odonata Biodiversity in Oil Palm Smallholdings ecosystems through altered hydrology and habitat availability (Luke et al, 2016, 2017). In Malaysia, agricultural land is estimated to cover 10.31 Mha of the total land area with oil palm plantation representing at least 5.74 M ha (Kushairi, 2017). These major changes of land use characteristics have contributed to different species composition from the original composition of the community (Che Salmah et al, 1998, 2014; Kadoya et al, 2009; Wong et al, 2016; Yahya et al, 2017). Low dissolved oxygen concentrations associated with organic pollution and eutrophication can reduce the survival of many aquatic fauna (Breitburg et al, 2003; Jones et al, 2006)

Objectives

Methods

Results

Discussion

Conclusion