Abstract Detail

Dynamics and Demography of Alpine Islands

McDonough MacKenzie, Caitlin [1], Miller-Rushing, Abraham [2], Gill, Jacquelyn [3].

Little Mountains, Big Implications: Alpine Mircorefugia in the Northeastern United States.

Alpine and subalpine plant communities in the northeastern United States are scattered across relatively low elevation peaks and ridges. These mountain habitats have long histories as conservation land, but their alpine and subalpine plants — culturally and ecologically important resources — often comprise small, disjunct populations at the southern edge of their circumboreal or circumarctic distributions. Northeast alpine and subalpine assemblages have been interpreted as post-glacial tundra relicts, however paleoecological records above treeline are sparse and this assumption remains untested. If mountains as small as Acadia National Park’s coastal summits (380-466 m) supported persistent alpine and subalpine vegetation throughout the Holocene, they could be considered alpine refugia. Globally, montane and alpine communities are highly vulnerable to climate change, deemed better barometers of change than microrefugia from it. While the northeast is warming faster than the contiguous United States, high elevations and coastal islands may be buffered from regional warming by cloud cover. On coastal mountains in Acadia there is evidence that local microclimate gradients are decoupled from elevation gradients. This kind of local-scale heterogeneity in microclimates has been associated with reduced extinction risk from climate change. Documenting the prevalence and spatial distribution of persistent tundra microrefugia in the northeast will provide critical context about the vulnerability of these iconic plant communities and allow conservation practitioners to focus management actions and refine extinction risk estimates for alpine and subalpine plants. Here, we bring together neoecology and paleoecology to assess climate change vulnerability at scales from annual phenology to centennial floristic change to millennial vegetation dynamics and position the small coastal mountains in Acadia as a preview of the effects of climate change on taller, larger alpine habitats across the region. We find reduced plasticity in flowering and leaf-out phenology in Acadia compared to lower latitude sites, and relatively high rates of local extirpations (10% of mountain species, 15.8% of the entire flora) over the last 125 years for a site that recently celebrated the centennial of its National Park status. Preliminary results from new paleoecological samples retrieved at a pond adjacent to the contemporary treeline indicate a mix of lowland and upland taxa appearing in the fossil record, including species not currently found at this pond. Together, these neo- and paleoecological studies reveal trends in alpine and subalpine vegetation dynamics at multiple temporal scales and help managers refine climate change vulnerability assessments.

1 - 4 Centre St, Cambridge, MA, 02139, United States
2 - PO Box 177, Bar Harbor, ME, 04609, United States
3 - University of Maine, Climate Change Institute, 134 Sawyer Research Labs, Orono, ME, 04469, USA

Keywords:
National Park
phenology
Paleoecology
microrefugia
Alpine
Maine.

Presentation Type: Colloquium Presentations
Session: CO02, Dynamics and demography of Alpine Islands
Location: San Luis 2/Starr Pass
Date: Monday, July 29th, 2019
Time: 8:00 AM
Number: CO02001
Abstract ID:673
Candidate for Awards:None