FLORISTIC CHANGE IN NEW ENGLAND AND NEW YORK: REGIONAL PATTERNS OF PLANT SPECIES LOSS AND DECLINE

Caitlin Mcdonough Mackenzie,Glen Mittelhauser,Richard B Primack,Abraham J Miller-Rushing

doi:10.3119/18-04

Caitlin Mcdonough Mackenzie, Glen Mittelhauser + Show 2 more

Open Access

https://doi.org/10.3119/18-04

Copy DOI

Abstract

The wealth of historical botanical surveys in New England and New York allows ecologists to study changes in plant communities over time across well documented sites. Studies of floristic change in towns, counties, and preserves over the past 150 years reveal regional patterns of species loss and increasing proportions of nonnative species. These changes are often linked to land use change, deer herbivory, development pressures, and climate change. Here, we review patterns of change throughout the region and explore in-depth floristic change at a northern site: Mount Desert Island (MDI), Maine, which holds the largest section of Acadia National Park. We find floras across the region have lost, on average, one-quarter of their native species—ranging from a loss of 3.5% of species from the Finger Lakes Region in New York to a loss of 53.1% of species on Staten Island, New York. No variable that we examine (e.g., size of area, size of flora, conservation status, and data sources) explains differences in losses across all sites. Contemporary floras have higher percentages of nonnative species than historic floras: the percent of nonnatives in floras have increased by 1.5% to 19.7% across the region. We also explore a data set of 412 conspecifics found both on MDI and 324 km away in Concord, Massachusetts, and compare species-level changes in abundance over the past century to test whether changes in one location might be predictive of changes in the other. We find that at a community level, changes in abundance in Concord were predictive of changes on MDI—local floras throughout the region have lost roughly 25% of their original species over the last 50 to 150 years—but changes in abundance for particular species in Concord were not predictive of how the same species changed in abundance on MDI. In New England, analyses of changes in nearby floras may help land managers and scientists understand community-level changes likely taking place, but we find that documenting and understanding changes in particular species requires targeted local study. Finally, we highlight the importance of context: understanding the survey effort, expertise, and goals of earlier botanists allows contemporary ecologists to make the most of the available historical ecological data.

Highlights

Concord were not predictive of how the same species changed in abundance on Mount Desert Island (MDI)
We did not attempt to make absolute comparisons between the categories of relative abundance used on MDI (Mittelhauser et al 2010) and Concord (Primack et al 2009), instead we focused on analyzing the relative changes at these locations
Of the 680 species recorded by Rand et al (1894), 15.8% are no longer found on MDI, 34.4% declined in abundance, 30.4% experienced no apparent change in abundance, and 19.4% increased in abundance [9 species from Rand et al (1894) did not have an abundance description]

Summary

Introduction

Concord were not predictive of how the same species changed in abundance on MDI. In New England, analyses of changes in nearby floras may help land managers and scientists understand community-level changes likely taking place, but we find that documenting and understanding changes in particular species requires targeted local study. The northeastern United States has an exceptionally rich history of botanical inventories pursued over the past two centuries by colonial surveyors (Cogbill et al 2002), environmental writers (Miller-Rushing and Primack 2008), botanical collectors (Davis et al 2015; Willis et al 2017; Daru et al 2017), professional and amateur scientists (Rand et al 1894), and managers of conservation lands (Sorrie and Dunwiddie 1996) This inventory work has provided universities, libraries, archives, and herbaria with unique and valuable historical ecological records (Vellend et al 2013a; McClenachan et al 2015; Beller et al 2017). Such a review could yield insights into region-wide changes in plant communities and potential causal factors associated with different rates and types of change. We present thirteen floristic change studies: nine from Massachusetts, two from New York, one from New Hampshire, and one from Maine (Figure 1)

Methods

Results

Discussion

Conclusion