Impacts of global changes on biodiversity and ecosystem functioning

Human exploitation of natural habitats is rapidly changing the natural world. Tropical areas, which support the majority of the world’s species, are disproportionately affected by this process. My work focuses on ant communities in SE Asian rainforest, which is threatened specifically by extraction of timber, and conversion to oil palm plantation. Oil palm expansion is one of the main drivers of deforestation in the area, but in two reviews of the literature (Turner et al. 2008, Foster et al. 2011) we found that only a tiny fraction of the oil palm articles published relate to biodiversity (less than 1% prior to 2008, rising to 4% in the period 2008-2011). I am interested in understanding how human-mediated habitat degradation impacts communities of animals and plants, the way that these species interact, and the way that ecosystems function. I am particulary interested in the use of experimental manipulations, specifically those that encompass entire ecosystems, to explore these questions (Fayle et al. 2015). I also contribute to some "big data" projects, which I think are very important (Hudson et al. 2014, Gibb et al. 2015).

During my PhD, supervised by William Foster and Paul Eggleton, in collaboration with Ed Turner (University of Cambridge), I compared the diversities of ants inhabiting primary (unlogged) forest, and oil palm plantation in Sabah, Borneo (Fayle et al. 2010). Since the effects of habitat conversion can be contingent on the heterogeneity of the habitats in question, we collected ants from three different microhabitats: the canopy (using insecticide fogging), leaf litter on the ground (using Winkler sampling) and from epiphytic bird’s nest ferns (Asplenium spp.), a highly abundant litter trapping epiphyte. We found that although species richness decreased in oil palm by 64%, this effect was not uniform across microhabitats, with declines being greatest in the canopy (52%) and leaf litter (74%), but with only a 3% decrease in epiphytic ferns. However, despite this resilience in terms of species richness, very few of the species found in oil palm were from primary forest (only 19% primary forest species remained across all three microhabitats). This indicates that increasing habitat heterogeneity by encouraging ferns may not be useful for helping to support ant biodiversity for conservation purposes, but does have the potential to be useful from an applied perspective, if resident ants perform ecosystem services, such as eating herbivores. More recently, I was involved in a collaboration showing that the ants (and other groups) that are lost when forest is converted to oil palm tend to be larger-bodied and come from higher trophic levels (Senior et al. 2013).

Not all forest is converted into plantation, with some remaining as logged forest. Understanding the ability of logged forest to support functioning ecosystems is therefore of importance. In collaboration with Paul Woodcock I have been involved in work investigating this for litter-dwelling ant communities (Woodcock et al. 2011). We found that even forest that had been logged twice still supported relatively large numbers of primary forest species (80%). This means that the impacts of converting logged forest into oil palm plantation (from 80% primary forest species to 13% primary forest species) are greater than those of converting primary forest into logged forest (100% to 80%), at least for leaf litter ants. I have also been involved in some work looking at the differences in canopy ant communities between primary forest and secondary forest (regrowth after clearing) in Papua New Guinea (Klimeš et al, 2012). We found that lower canopy ant species richness in secondary forest was caused mainly by reduced tree density, and smaller numbers of very large trees. Surprisingly, differences in tree taxonomic diversity were less important in driving differences in ant diversity, because ants are not very species-specific with regard to their host tree.

Sometimes when forests are cleared for plantation, isolated areas are left, creating a landscape of forest fragments within a matrix of oil palm. I am now working in collaboration with the Stability of Altered Forest Ecosystems project (SAFE) to investigate the effects of forest fragmentation on ant diversity (Turner et al. 2011, Turner et al. 2012). In a collaboration involving Rob Ewers (Imperial College London), Ed Turner (University of Cambridge) and Kalsum Mohd Yusah (Universiti Malaysia Sabah), we are sampling litter ants (pitfall traps and winkler samples), and canopy ants (fogging) in areas that are in the process of becoming fragments. SAFE is the largest experimental forest fragmentation project globally, with six blocks of forest fragments, each comprising one 100ha fragment, two 10ha fragments and four 1ha fragments. We are interested in the interactions between fragment size and local landscape cover in determining ant species persistence. To date, work at SAFE has focussed on aspects of the gradient other than fragmentation, while pre-fragmentation data is collected (Konopik et al. 2014, Luke et al. 2014, Ewers et al. 2015, Gray et al. 2015).

Ants are expected to play an important role in the functioning of ecosystems, since they are involved in many vital processes, such as turning over soil and eating herbivorous insects, and form relationships with many other animals and plants. I am particularly interested in the ways that ants might affect soil properties through redistribution of nutrients and the turning over of soil. While teaching on a Tropical Biology Association field course a couple of years ago I ran a class field exercise in which we assessed rate of bait removal by ants along a gradient from forest into cleared areas (Fayle et al. 2011). We found that although ant diversity and bait removal rate did not change along the gradient, ant species richness was still a good predictor of how much bait was removed. Extending this work, in collaboration with Claudia Gray, we developed a standardised assay for nutrient redistribution (assessed through rates of bait removal) at larger spatial scales in the SAFE experimental area. We found that riparian strips in oil palm plantations maintained similar rates of nutrient redistribution to continuous forest, and these rates were higher than that for oil palm (Gray et al. 2015). This was because the ant communities in the riparian strips were similar to those found in continuous forest. In a study bringing together SAFE data from the first five years of the project looking at a wider range of ecosystem processes (litter decomposition, seed predation and removal, and invertebrate predation), led by Rob Ewers, we found that declines in invertebrates (including ants), relative to vertebrates resulted in a decrease in their functional importance in logged forest relative to primary forest (Ewers et al. 2015). I also contributed to a book chapter describing the links between soil biodiversity and ecosystem functioning (Brussard et al. 2012).

References

Fayle T.M., Turner E.C., Bassett Y., Ewers R.M., Reynolds G. & Novotny V. (2015) Whole-ecosystem experimental manipulations of tropical forests. Trends in Ecology and Evolution 30: 334–346 [PDF]

Gray C., Lewis O., Chung A.Y. & Fayle T.M. (2015) Riparian reserves within oil palm plantations conserve logged forest leaf litter ant communities and maintain associated scavenging rates. Journal of Applied Ecology 52: 31-40 [PDF]

Ewers R.M., Boyle M.J.W., Gleave R., Plowman N.S., Benedick S., Bernard H., Bishop T.R., Bakhtiar E.Y., Chey V.K., Chung A.Y.C., Davies R.G., Edwards D.P., Eggleton P., Fayle T.M., Hardwick S.R., Homathevi H., Kitching R.L., Khoo M.S., Luke S.H., March J.J., Nilus R., Pfeifer M., Rao S.V., Sharp A.C. Snaddon J.L., Stork N.E., Struebig M.J., Wearn O.R., Yusah K.M., and Turner E.C. (2015) Logging cuts the functional contribution of invertebrates in tropical rainforest. Nature Communications 6: 6836 [PDF]

Gibb H., Sanders N.J., Dunn R.R., Photakis M., Abril S., Andersen A.N., Angulo E., Armbrecht I., Arnan X., Baccaro F.B., Boulay R., Castracani C., Del Toro I., Delsinne T., Diaz M., Donoso D.A., Enríquez M.L., Fayle T.M., Feener Jr. D.H., Fitzpatrick M., Gómez C., Grasso D.A., Groc S., Heterick B., Hoffmann B., Lach L., Lattke J., Leponce M., Lessard J-P., Longino J., Lucky A., Majer J., Menke S.B., Mezger D., Mori A., Paknia O., Pearce-Duvet J., Pfeiffer M., Philpott S., de Souza J.P.L, Tista M., Vonshak M., Parr C.L. (2015) Climate regulates the effects of anthropogenic disturbance on ant assemblage structure. Proceedings of the Royal Society B: Biological Sciences 282: 20150418 [PDF]

Hudson L., Newbold T., [100s of co-authors including Fayle T.M.] & Purvis, A. (2014) The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts. Ecology and Evolution 4: 4701–4735 [PDF]

Luke S.H., Fayle T.M., Eggleton P., Turner E.C. & Davies R.G. (2014) Abundance and functional structure of ant and termite assemblages along a tropical forest disturbance gradient in Sabah, Malaysia. Biodiversity and Conservation 23: 2817–2832. [PDF]

Senior M.J.M., Hamer K.C., Bottrell S., Edwards D.P., Fayle T.M., Lucey J.M., Mayhew P.J., Newton R., Peh K. S.-H., Sheldon F.H., Stewart C., Styring A.R., Thom M.D.F., Woodcock P. & Hill J.K. (2013) Trait-dependent declines of species following conversion of rain forest to oil palm plantations. Biodiversity and Conservation 22: 253-268. [PDF]

Fayle T.M. & Polaszek A. (2013) Wallace's legacy: from biogeography to conservation biology. Antenna: 37: 172-175. [PDF]

Klimeš P., Idigel C., Rimandai M., Fayle T.M., Janda M., Weiblen G.D. & Novotný V. (2012) Why are there more arboreal ant species in primary than secondary tropical forests? Journal of Animal Ecology 81: 1103–1112. [PDF]

Brussaard L., Aanen D.K., Briones M., Decaëns T, De Deyn G.B., Fayle T.M. & James S.W. (2012) Biogeography and phylogenetic community structure of soil invertebrate ecosystem engineers: global to local patterns and implications for ecosystem functioning and global environmental change impacts. In Wall D.H. et al. (Eds.) Soil Ecology and Ecosystem Services. Oxford University Press, UK. [PDF]

Turner E.C., Abidin Y.Z., Barlow H., Fayle T.M., Jaafar M.H.H.J., Khen, C.V., Larenus J., Nainar A., Reynolds G., Yusof B.Y., Khoo M.S. & Ewers R.M. (2012) The Stability of Altered Forest Ecosystems Project: Investigating the design of human-modified landscapes for productivity and conservation. The Planter 88: 453-468 [PDF]

Fayle T.M., Bakker L., Cheah C., Ching T.M., Davey A., Dem F., Earl A., Huaimei Y., Hyland S., Johansson B., Ligtermoet E., Lim R., Lin L.K., Luangyotha P., Herlander Martins B., Palmeirim A.F., Paninhuan S., Kepfer Rojas S., Sam L., Sam P.T.T., Susanto D., Wahyudi A., Walsh J., Weigl S., Craze P.G., Jehle R., Metcalfe D. & Trevelyan T. (2011) A positive relationship between ant biodiversity (Hymenoptera: Formicidae) and rate of scavenger-mediated nutrient redistribution along a disturbance gradient in a south-east Asian rain forest. Myrmecological News 14: 5-12. [PDF]

Woodcock P., Edwards D.P., Fayle T.M., Newton R.J., Chey V.K.. Bottrell S.H. & Hamer K.C. (2011) The conservation value of Southeast Asia’s highly degraded forests: evidence from leaf-litter ants. Philosophical Transactions of the Royal Society B 366: 3256-3264. [PDF]

Foster W.A., Snaddon J.L., Turner E.C., Fayle T.M., Cockerill T.D., Ellwood M.D.F., Broad G.R., Chung A.Y.C., Eggleton E., Chey V.K. & Yusah K.M. (2011). Establishing the evidence base for maintaining biodiversity and ecosystem function in the oil palm landscapes of South East Asia. Philosophical Transactions of the Royal Society B 366: 3277-3291. [PDF]

Turner E.C., Snaddon J.L., Ewers R.M., Fayle T.M. & Foster W.A. (2011). The Impact of Oil Palm Expansion on Environmental Change: Putting Conservation Research in Context. In Bernardes M.A.S. (Ed.) Environmental Impact of Biofuels. InTech Press. [PDF]

Fayle T.M., Turner E.C., Snaddon J.L., Chey V.K., Chung A.Y., Eggleton P.E. & Foster W.A. (2010). Oil palm expansion into rain forest greatly reduces ant biodiversity in canopy, epiphytes and leaf litter. Basic and Applied Ecology 11: 337-345. [PDF]

Turner E.C., Snaddon J.L., Fayle T.M. & Foster W.A. (2008). Oil Palm Research in Context: Identifying the Need for Biodiversity Assessment. PLoS ONE 3: e1572. [PDF]