Museum of Zoology, Insect Ecology Group
New research from the Museum of Zoology and collaborators finds a diverse and variable dragonfly community in oil palm plantations in Sumatra, Indonesia.
Across the globe, large areas of naturally forested habitats have been converted to agriculture to feed a growing world population. This conversion usually results in dramatic changes in the habitat, including losses of habitat complexity, and changes in environmental conditions such as temperature and nutrient levels. This is often bad news for biodiversity, including species such as pollinators, which farmers depend on to maintain crop yields.
To strike a successful balance between the needs of agriculture and the environment in the long term, it is essential that we develop agricultural management strategies that are more wildlife-friendly.
Investigations into sustainable oil palm plantation management:
The Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme is a long-term research collaboration between the University of Cambridge, other universities, and the oil palm industry in Sumatra, Indonesia.
Oil palm, which produces palm oil – used in a wide range of processed foods, cosmetics, and as a cooking oil – is one of the most important crops in Indonesia. Although it supports far less biodiversity than forest, oil palm has the potential to support more biodiversity than many other crops, owing to its long lifespan.
The BEFTA Programme is running a series of large-scale, long-term experiments with the aim of better understanding the oil palm agroecosystem (agricultural ecosystem) and testing strategies for sustainability.
Helpful predators of the water and skies
Dragonflies and damselflies (known collectively as Odonata), are charismatic and showy insects that are found in a wide variety of habitats. Because their larvae develop in water, whilst the adults rely on resources from the land, dragonflies and damselflies can be affected by a range of impacts and so can be valuable ‘indicators’ (signal) of environmental changes that are happening across landscapes.
They also play important roles as predators in and around waterbodies, and as prey for other species, including birds. This means that any losses or changes in their community could have big knock-on effects within ecosystems.
Oil palm plantations are an increasingly common type of land use across the tropics, however very few studies have assessed the Odonata communities that live within them, and what might affect their abundance and the species that are found there.
To investigate what species of Odonata were found within oil palm landscapes, and how they were affected by plantation management strategies, we conducted surveys over several years within oil palm plantations in Sumatra, Indonesia. This is part of the larger BEFTA programme.
We found a large number of dragonfly and damselfly species living within the plantation. The species we found varied between the core of oil palm planting blocks and roadside edges, and in relation to rainfall levels. However, we did not find much effect of varying ground-level plant (understory vegetation) growth and management on the Odonata community, suggesting that local understory vegetation structure does not play a very big role in determining the species of dragonflies and damselflies found.
Taken together, our results highlight that there are large numbers of dragonfly and damselfly species found within oil palm plantations, and that their abundance could perhaps be increased further by maintaining or establishing waterbodies to provide more habitat for development of their larvae. As Odonata are predators, there’s a chance this could bring pest control benefits, in addition to enhancing biodiversity within intensive agricultural landscapes.
The bigger picture
The four key components of the BEFTA research programme are:
- Assessing the current levels of environmental conditions, biodiversity, and ecosystem functions within the plantation under business-as-usual conditions, and quantifying how variable they are.
- The BEFTA Understory Vegetation Project, which tests the effects of using different levels of herbicide spraying to control vegetation on the ground beneath the palms.
- The Riparian Ecosystem Restoration in Tropical Agriculture (RERTA) Project, which tests strategies for restoring conservation habitat on riverbanks within plantations.
- Supporting additional collaborative projects within the Programme landscape.
Early results suggest that the oil palm plantation habitat is more variable than might be expected from a monoculture crop, which has sometimes been termed a ‘green desert’, and that everyday management decisions within plantations can have a big influence on habitat structure, and therefore the biodiversity and ecosystem functioning.
Open access to the most recent papers on BEFTA Programmes and oil palm monoculture can be found here:
Luke SH, Advento AD, Aryawan AAK, et al (2020) Managing Oil Palm Plantations More Sustainably: Large-Scale Experiments Within the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme. Front For Glob Chang 2: . doi: 10.3389/ffgc.2019.00075
Luke SH, Dwi Advento A, Dow RA, et al (2020) Complexity within an oil palm monoculture: The effects of habitat variability and rainfall on adult dragonfly (Odonata) communities. Biotropica 52:366–378 . doi: 10.1111/btp.12749