The conservation value of oil palm plantation estates, smallholdings and logged peat swamp forest for birds Badrul Azhar a,b,⇑ , David B. Lindenmayer a , Jeff Wood a , Joern Fischer c , Adrian Manning a , Chris McElhinny a , Mohamed Zakaria b a The Fenner School of Environment and Society, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra ACT 0200, Australia b Department of Forest Management, Faculty of Forestry, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia c Faculty of Sustainability, Leuphana University Lueneburg, 21335 Lueneburg, Germany article info Article history: Received 4 May 2011 Received in revised form 9 August 2011 Accepted 11 August 2011 Available online 9 September 2011 Keywords: Bird assemblages Management regime Oil palm Species richness Stand age Vegetation structure abstract The expansion of industrial oil palm cultivation threatens tropical biodiversity globally, especially in developing countries. Driven by plans to generate economic revenue, large-scale plantations are emerg- ing in Southeast Asia, Africa and Brazilian Amazon. However, the ecological impacts of the sector are poorly studied with respect to oil palm management system, and recommended conservation measures are based on limited data. We studied avifauna in oil palm landscapes in Peninsular Malaysia under dif- ferent management systems (large plantation estates versus smallholdings) and age classes (uniform age versus mixed-age stands). We sampled 41 large plantation estates and 14 smallholdings, as well as 20 sites in an extensively logged peat swamp forest, the type of natural forest prior to conversion to oil palms. Compared with logged peat swamp forest, our results showed that forest conversion to oil palm cultivation may have eliminated 48–60% of bird species. We also found: (i) plantation estates and small- holdings supported similar bird assemblages but the latter supported significantly more species (P = 0.007); and (ii) despite reduced species richness in oil palm landscapes, we found high abundance of some individual bird species in specific types of stands including some forest, migratory, and wetland species. Conversion of natural forest to oil palm landscapes should not occur in the future through clear- ing of primary or secondary native forests. To complement conventional conservation approaches (e.g. the establishment of protected areas) in palm oil-producing countries, existing plantation estates and smallholdings should be managed in ways to promote improved conservation outcomes, although oil palm landscapes maintained a fraction of the original forest biodiversity. Managing habitat heterogeneity at both a local and a landscape-level is highly recommended in oil palm landscapes to maintain and/or enhance avian biodiversity. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction Oil palm Elaeis guineensis cultivation is a major driver of the cur- rent biodiversity crisis in tropical South-east Asia. Oil palm cultiva- tion is becoming more widespread worldwide despite being considered by environmental NGOs as a serious threat to forest biodiversity (Danielsen et al., 2009; Lambert and Collar, 2002; Fitzherbert et al., 2008; Rudel et al., 2009; Sodhi et al., 2004; Sodhi and Brook, 2006). As of 2008, the planted area of oil palm in Malaysia alone covered approximately 4.5 million ha and produced 18 million tonnes of palm oil per year (Malaysia Palm Oil Board, 2009). The oil palm plantation business is expanding rapidly not only in Southeast Asia, but also other regions such as Equatorial Africa and South America, especially Brazil (Butler and Laurance, 2009; Wilcove and Koh, 2010). Weak governance and corruption issues in some palm oil-producing countries are acknowledged as accelerating deforestation (Laurance, 2004), and poor compliance with environmental standards by plantation companies is exacer- bating this problem (Fitzherbert et al., 2008). Certification systems such as the Roundtable on Sustainable Palm Oil (RSPO) lack scientific evidence to support measures to conserve biodiversity within oil palm landscapes (Laurance et al., 2010). For instance, Donald (2004) highlighted how the impacts of different management regimes remain understudied by ecolo- gists. Limited empirical work has quantified bird communities in relation to stand age characteristics or management regimes in oil palm landscapes. Only two studies (Danielsen and Heegaard, 1995; de Chenon and Susanto, 2006) have emphasized such effects as being a potentially important factor influencing biodiversity. On 0378-1127/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2011.08.026 ⇑ Corresponding author at: The Fenner School of Environment and Society, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra ACT 0200, Australia. Tel.: +61 2 61258136; fax: +61 2 61250757. E-mail address: badrul.sharif@anu.edu.au (B. Azhar). Forest Ecology and Management 262 (2011) 2306–2315 Contents lists available at SciVerse ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco