The future of terrestrial species will largely depend on their ability to persist in working landscapes. Agriculture now occupies ~50% of Earth’s land surface, yet biologists and conservation managers often overlook opportunities for pursing wildlife conservation in farming landscapes. Our research has documented that tropical diversified farming systems— with high crop diversity and patches of native vegetation— can sustain remarkable concentrations of biodiversity (Fig. 1). Using a 12-yr dataset of 120,000 bird encounters across 487 species in four regions of Costa Rica, we showed that tropical bird communities were more resilient and stable in diversified farms than in intensive monocultures (Karp et al. 2011 PNAS). We also found that diversified farms hosted nearly double the number of species as monocultures, while still maintaining community turnover (β-diversity) on par with native forest (Karp et al. 2012 Ecology Letters). In contrast, monocultures homogenized biodiversity through simplifying vegetation structure and favoring a limited set of closely related species. High extirpation rates of evolutionarily distinct birds caused phylogenetic diversity to plummet in monocultures (Frishkoff*, Karp* et al. 2014 Science). Diversified farms, however, housed ~600 million more years of evolutionary history than monocultures.
Fig. 1: Diversified farms maintain high avian alpha-diversity (Karp et al. 2011 PNAS), beta-diversity (Karp et al. 2012 Ecology Letters), and phylogenetic diversity (Frishkoff*, Karp* et al. 2014 Science).
In 2016, the Karp Lab developed a study system in Northwest Costa Rica to explore forward-looking conservation strategies for Neotropical birds. Across 150 sites in nature reserves, farms, and privately-owned forest patches, our team mapped forest cover, modeled precipitation, surveyed vegetation, and conducted bird censuses for four years. We found that diverse bird communities can be found in agriculture (Echeverri et al. 2019 Div. & Dist.), but species responses to agriculture are often scale-dependent, context-dependent, species-specific, and nonlinear (Frishkoff & Karp 2019 Ecol. App.).
Despite such complexity, we uncovered several novel insights of direct relevance to our local conservation partners. First, species of conservation concern are rare in agriculture, but thrive in privately-owned forests, even though these forests are twice as fragmented and more disturbed than nature reserves (Karp et al. 2019 J. Appl. Ecol.). In particular, we found that narrow-ranged species associated with wetter conditions flourished in forests, whereas wide-ranging, dry-adapted species dominated agriculture (Karp et al. 2018 Glob. Chan. Bio.). Contrary to prior ecological theory, our work suggested that these correlated responses among Neotropical birds to climate change and habitat conversion will likely exacerbate future biodiversity loss (Frishkoff et al. 2018 Oikos). Fortunately, our models also suggest that prioritizing restoration in wetter, more forested regions would significantly bolster species of conservation concern and mitigate the interactive impacts of ongoing climate drying and deforestation on tropical birds (Karp et al. 2019 J. Appl. Ecol.)
Over the last year, our lab has expanded these lines of inquiry into similar landscapes in Colombia and Ecuador. Specifically, in 2018, graduate student Alison Ke worked with Profs. Juan-Pablo Gomez and Gustavo Londoño to organize a parallel bird censusing strategy across 144 sites in Colombia. Then, beginning in 2019, she began collaborating with Prof. Jordan Karubian to study birds in agro-ecosystems in Ecuador. Looking forward, many questions remain regarding how agriculture affects tropical biodiversity and what we can do to best manage working landscapes for people and wildlife. For example…
1. Do the same dry-associated species dominate agriculture in Central and South America? If so, then habitat loss and climate change may be homogenizing biodiversity at continental scales.
2. What mechanisms underlie species responses to global change? Can bird physiology, diet preferences, or nest predation explain why climate change and habitat loss favor similar species?
3. Are agricultural systems more competitive environments than forested systems?
4. Do Neotropical birds suffer lower reproduction in agriculture, making agriculture an ‘ecological trap’? If so, can providing artificial nest boxes improve species’ prospects in agriculture?
Check out a video synopsis of our ongoing work:
- Echeverri, A., L.O. Frishkoff, J.P. Gomez, J.R. Zook, P. Juárez, R. Naidoo, K.M.A. Chan, and D.S. Karp (2019) Precipitation and tree cover gradients structure avian alpha-diversity in Northwestern Costa Rica. Diversity and Distributions. 25: 1222-1233.
- Frishkoff, L.O. and D.S. Karp (2019) Species‐specific responses to habitat conversion across scales synergistically restructure Neotropical bird communities. Ecological Applications 29: e01910.
- Karp, D.S., A. Echeverri, J. Zook, P. Juárez, A. Ke, J. Krishnan, K.M.A. Chan, and L.O. Frishkoff (2019) Remnant forest on private land fosters Neotropical bird communities that are indistinguishable from formal reserves. Journal of Applied Ecology. 56: 1839-1849.
- Frishkoff, L.O., A. Ke, I. Martins, E. Olimpi, and D.S. Karp (2019) Countryside Biogeography: The controls of species distributions in human-dominated landscapes. Current Landscape Ecology Reports 4: 15-30.
- Frishkoff, L.O., A. Echeverri, K.M.A. Chan, and D.S. Karp (2018) Do correlated responses to multiple environmental changes exacerbate or mitigate species loss? Oikos 127: 1724-1734.
- Karp, D.S., L.O. Frishkoff, A. Echeverri, J. Zook, P. Juárez, and K.M.A. Chan (2018) Agriculture erases climate-driven b-diversity in Neotropical bird communities. Global Change Biology 24: 338-349.
- Frishkoff, L.O., D.S. Karp, J.R. Flanders, J. Zook, E.A. Hadly, G.C. Daily, and L.K. M’Gonigle. (2016) Climate and land-use change interact synergistically by favoring the same species. Ecology Letters 19: 1081-1090
- Wood, S., D.S. Karp, F. DeClerke, C. Kremen, S. Naeem, and C. Palm (2015) A functional trait approach for understanding the impacts of biodiversity in agriculture. Trends in Ecology and Evolution 30: 531-539.
- Frishkoff, L.*, D.S. Karp*, C.D. Mendenhall, L. M’Gonigle, C. Kremen, E.A. Hadly, and G.C. Daily. (2014) Loss of avian phylogenetic diversity in Neotropical agricultural systems. Science 345: 1343-1346. *= shared first authorship
- Mendenhall, C.D., D.S. Karp, C.F.J. Meyer, E.A. Hadly, and G.C. Daily. (2014) Predicting biodiversity change and averting collapse in agricultural landscapes. Nature 509: 213-217.
- Karp, D.S., A.J. Rominger, J. Zook, J. Ranganathan, P.R. Ehrlich, and G.C. Daily (2012) Intensive agriculture erodes b-diversity at large scales. Ecology Letters 15: 963-970. Faculty of 1000.
- Karp, D.S., G. Ziv, J. Zook, P.R. Ehrlich, and G.C. Daily (2011) Resilience and stability in bird guilds across tropical countryside. Proceedings of the National Academy of Sciences 108: 21134-21139.
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