Abstract Detail

Dynamics and Demography of Alpine Islands

Jabis, Meredith Diana [1], Germino, Matthew [2], Kueppers, Lara [3].

Migration of trees into the alpine tundra: Alpine neighbors assist late-seral but not early-seral conifer seedlings.

Climate change is projected to alter the altitude and latitude of the treeline globally, however seed germination and seedling survival is a critical local control on the expansion or contraction of treeline. The realized climatic conditions that colonizing seedlings will experience is a product of both the ambient climate and interactions with plant neighbors. Recruiting conifers may have to compete with alpine plants or they may be facilitated via protection from the intense alpine environment by neighbors during establishment. To determine whether neighboring plant species can alter the success of seedling recruitment into the alpine tundra ecosystem in the context of climate change, we conducted a controlled replicated experiment with two treeline conifer species. Within the alpine tundra on Niwot Ridge, CO, we imposed crossed active heating and watering manipulations in a common garden experiment and removed neighboring plants from emerging conifer seedlings and a naturally occurring mature alpine herb. Consistent with its late-seral status, Picea engelmaniiseedlings showed lower survival as compared with Pinus flexilisthree weeks following neighbor removal, and one year following only survived in watered plots. P. engelmaniialso had the highest instantaneous water use efficiency (WUE) of all three species. Consistent with its early-seral status, limber pine seedlings were less sensitive to alpine neighbors, and responded to neighbor removal by lowering the quantum yield of photosynthesis (ϕ_PSII), or reducing WUE when also heated. Contrary to expectations from the stress gradient hypothesis, at the low stress and low elevation edge of an alpine herb’s range, survival of Chionophila jamesiiwas lower without neighbors regardless of climate treatment. Results suggest that P. flexilishas the highest invasion potential into the alpine tundra ecosystem due to its ability to tolerate warmer and drier conditions, which appears to relieve the necessity of neighbor facilitation, while Engelmann spruce will require neighbor facilitation to expand its range.  Given future climate change this could mean a range expansion for limber pine and a concomitant land cover change with likely consequences for alpine plant diversity and ecosystem function.

1 - UC Berkeley, Environmental Science Policy and Management, 130 Mulford Hall #3114 , University of California, Berkeley, Berkeley, CA, 94720-3114, USA
2 - USGS, 970 Lusk St, Boise, ID, 83706, United States
3 - UC Berkeley, Energy and Resources Group, 310 Barrows Hall, University of California Berkeley, Berkeley, CA, 94720-3050, USA

Keywords:
Alpine
climate change
tree migration
facilitation
plant neighborhood
stress gradient hypothesis.

Presentation Type: Colloquium Presentations
Session: CO02, Dynamics and demography of Alpine Islands
Location: San Luis 2/Starr Pass
Date: Monday, July 29th, 2019
Time: 10:45 AM
Number: CO02011
Abstract ID:383
Candidate for Awards:None