Producing Diversity: Agroforests Sustain Avian Richness and Abundance in India's Western Ghats

Krithi K Karanth,Paul Robbins,Arjun Srivathsa,Sushma Sharma,Vishnupriya Sankararaman,Ashwini Chhatre,Shashank Dalvi,Ravishankar Parameshwaran

doi:10.3389/fevo.2016.00111

Abstract

Globally, protected areas have long been the corner stone of biodiversity conservation efforts. In India’s Western Ghats, small and isolated protected areas are embedded in a matrix of multiple land-uses, most of which include agroforests. These agroforests are being increasingly recognized for their supplementary role in conserving wildlife. We examined bird species richness and densities in areca (Areca catechu), coffee (Coffea arabica and Coffea canephora) and rubber (Hevea brasiliensis) agroforests in the Western Ghats. We developed a priori hypotheses, predicting that bird species richness and guild density would be highest in coffee, followed by areca and rubber agroforests. We carried out 551 point-count surveys involving 386 hours of sampling in 187 agroforests across a 29,634 km2 area of the Ghats. We observed 204 bird species, of which 170 were residents. The average estimated richness per agroforest was higher in coffee (60.5) compared to rubber (45.4) and areca (34.1). We modeled species richness as a function of relevant biogeographic and environmental covariates. The most influential factors were tree cover, tree density and rainfall in all agroforests, but the strength of these effects varied. Coffee supported higher densities in all four habitat and three feeding guilds compared to areca and rubber. We integrated extensive field sampling with modeling that accounted for imperfect detection, while assessing bird richness and densities across multiple agroforest types. We establish that coffee agroforests are substantially richer in birds than rubber and areca, but all three agroforests play an important role in providing subsidiary habitats for birds in the Ghats. Policy decisions and markets must incorporate such biodiversity values and services provided by these agroforests to sustain and facilitate long-term biodiversity conservation.

Highlights

Agroforests and cultivated areas are globally recognized as important habitats for biodiversity (Balmford et al, 2005; Fischer et al, 2008; Beaudrot et al, 2016)
Average estimated species richness was highest in coffee SRc = 58.21 (SE = 1.85) and ranged from 33 to 105 species (Table 1)
We examined patterns and predictors of bird species richness, guild density and abundance in agroforests of areca, coffee and rubber in India’s Western Ghats

Summary

Introduction

Agroforests and cultivated areas are globally recognized as important habitats for biodiversity (Balmford et al, 2005; Fischer et al, 2008; Beaudrot et al, 2016). Covering 38% of the planet’s landmass, production landscapes such as tea, coffee, rubber, cacao, arecanut, and rice are known to support a diversity of birds, mammals, amphibians and other ecologically sensitive species in the tropics (Bhagwat et al, 2005; Faria et al, 2006; Perfecto and Vandermeer, 2008; Gardner et al, 2009; Anand et al, 2010; Foley et al, 2011; Robbins et al, 2015; Warren-Thomas et al, 2015) These human-cultivated landscapes support particular species or taxonomic groups, making it essential to understand which species persist and why they persist in such habitats (Daily et al, 2001; Bhagwat et al, 2008; de Lima et al, 2013; Maas et al, 2013; Mendenhall et al, 2014; Pryde et al, 2016). Intensification of management practices in agroforests may cause cascading effects on surrounding biodiversity

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