Impacts of land cover change on the plant resources of an endangered pollinator.

Emma P Gómez-Ruiz,José Juan Flores Maldonado,Thomas E Lacher Jr,Antonio Moreno-Talamantes

doi:10.7717/peerj.11990

Abstract

One of the key drivers of pollinator declines is land cover change. We documented for the first time the impacts of over three decades of land cover change in Mexico on the plant resources of an endangered migratory pollinator, the Mexican long-nosed bat, Leptonycteris nivalis. This species is considered endangered under national and international criteria due to population declines over 50% in the past 10 years. Pregnant females of this bat species migrate every year following the blooms of Agave spp. from central Mexico to the southern United States; moving pollen over its 1,200 km long migratory corridor and pollinating distant populations of Agave spp. Increases in human populations density and agricultural expansion may be reducing agave habitat over time. The objective of our study is to understand the land cover change trends in the northern range of the bat and identify potential fragmentation patterns in the region. We analyzed changes that occurred in three vegetation types where agaves are found in five time periods 1985, 1993, 2002, 2007 and 2011. The area of the three vegetation types selected was reduced by using only the overlap with potential agave habitat created with ecological niche modeling algorithms to obtain the available agave habitat. We then calculated fragmentation metrics for each period. We found a significant portion of habitat lost mainly due to expansion in agriculture. The total number of patches increased after 1985. Only 9% of the available agave habitat in 2011 is inside the limits of protected areas. We recommend restoring agave populations in depleted areas to help prevent soil erosion and provide multiple socio-economic benefits for the region in the short term, and, in the long-term maintaining foraging resources for nectar-feeding bats.

Highlights

Human impacts on planetary biodiversity have increased greatly over the past century, prompting some conservationists to propose that we have entered a defining new period, the Anthropocene (Lewis & Maslin, 2015)
The land cover change analysis indicates that desert scrub was the class with the largest negative net change from 1985 to 2011, and most of this change occurred between 1985 and 2002 (Fig. 2)
The fragmentation and disturbance on the available agave habitat can result in the lack of mature agave to produce flowers, and this would disrupt L. nivalis migration. Climate change is another factor that would affect the distribution of agave habitat (Gómez-Ruiz & Lacher Jr, 2019), for this study we focused on direct human-driven land-use changes

Summary

Introduction

Human impacts on planetary biodiversity have increased greatly over the past century, prompting some conservationists to propose that we have entered a defining new period, the Anthropocene (Lewis & Maslin, 2015). Declines in biodiversity vary across taxa and are driven by multiple threats, including habitat loss and fragmentation, climate change, and overconsumption (Lacher & Roach, 2018). There is agreement that habitat loss because of human-induced land cover change is currently the most important factor contributing to biodiversity declines in Earth’s terrestrial ecosystems (Millenium Ecosystem Assessment, 2005; Newbold et al, 2015; Chaudhary & Mooers, 2018)

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Discussion

Conclusion