Landscape effects on multi-taxa diversity in experimental tree islands

Landscape homogenization due to forest conversion to large scale agricultural landscapes such as oil palm monocultures is a major driver of biodiversity loss in the tropics. The challenge is balancing the provisioning services of these agricultural landscapes while enhancing and maintaining biodiversity and ecosystem functioning. In such cases, spatially patterned methods such as applied nucleation, the establishment of "tree islands" in human-modified landscapes, may contribute towards enhancing biodiversity and ecosystem functioning (Teuscher et al., 2016; Zahawi & Augspurger, 2006). However, the success of “tree islands” may depend on interactions among the tree island characteristics, the surrounding landscape, and the ecological processes operating at various spatial scales across multiple taxonomic groups (Miguet et al., 2016; Newman et al., 2019). Thus, understanding what properties and processes operate at what spatial scale(s) is important in optimizing the design of such restoration landscapes.

This study explores the relationships between landscape structure and multi-taxa diversity and ecosystem functioning in experimental tree islands embedded in an oil palm landscape (EFForTS-BEE) by adopting the focal patch multiscale approach (Brennan et al., 2002). This study aims to:

  1. Describe how the influence of landscape structure on multi-taxa diversity and ecosystem functioning changes with scale (i.e. spatial extent);
  2. Examine how the characteristics of tree islands and the surrounding landscape shape multi-taxa diversity and ecosystem functioning at local scales;
To accomplish these objectives, I use diversity estimates of various taxonomic groups including birds, trees, herbs, insects, soil fauna, fungi and bacteria in each of 52 tree islands. Using point locations of single isolated trees and a land-use map of the EFForTS-BEE landscape, I calculate contrasting landscape metrics to characterize the landscape around each tree island at 12 different spatial extents. Then, I assess the influence of the surrounding landscape on diversity of multiple taxa at local scales for each spatial extent using univariate and multivariate linear regressions, model selection and averaging.

This master thesis is supervised by Nathaly Guerrero and Clara Zemp.

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  • Miguet P, Jackson HB, Jackson ND, Martin AE, Fahrig L (2016) What determines the spatial extent of landscape effects on species? Landscape Ecology, 31(6), 1177–1194.
  • Newman EA, Kennedy MC, Falk DA, McKenzie D (2019) Scaling and Complexity in Landscape Ecology. Frontiers in Ecology and Evolution, 7.
  • Teuscher M, Gérard A, Brose U, Buchori D, Clough Y, Ehbrecht M, Hölscher D, Irawan B, Sundawati L, Wollni M, Kreft H (2016) Experimental Biodiversity Enrichment in Oil-Palm-Dominated Landscapes in Indonesia. Frontiers in Plant Science, 07.
  • Zahawi RA, Augspurger CK (2006) Tropical forest restoration: Tree islands as recruitment foci in degraded lands of Honduras. Ecological Applications: A Publication of the Ecological Society of America, 16(2), 464–478.[0464:tfrtia];2