A Region-Wide Shift From Aspens to Conifers Due to Climate Change May Imperil Biodiversity and Reproductive Success of Birds

EPA Grant Number: FP917477
Title: A Region-Wide Shift From Aspens to Conifers Due to Climate Change May Imperil Biodiversity and Reproductive Success of Birds
Investigators: LaManna, Joseph A
Institution: University of Montana
EPA Project Officer: Michaud, Jayne
Project Period: August 27, 2012 through August 26, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Terrestrial Systems Ecology


Climate change likely is influencing animal reproduction and diversity via its effects on habitat. This study will determine if a shift from aspen to conifers is associated with climate change at a region-wide scale and which habitat elements differ among these two habitats and lead to reproductive success and sustainable biodiversity. Using this information, the study will then project future region-wide shifts in the distributions of aspens, conifers and bird diversity that incorporate reproductive success.


Region-wide forest distributions will be generated from satellite and aerial photos, and state-transition models will test for an association with climate change. The study will examine bird reproductive success and the insect and vegetation communities in 11 mixed aspen-conifer sites in the Mt. Haggin Wildlife Management Area near Anaconda, MT, and in the White Sulphur Springs Ranger District of Lewis and Clark National Forest. These sites vary in their conifer composition, and the study will associate bird reproduction and diversity with insect and vegetation variables along this aspen-to-conifer gradient. In addition, conifers were removed from within and around three sites in the fall of 2010. This experimental design allows for spatial and temporal controls (i.e., Before- After-Control-Impact [BACI] design) and will experimentally validate the effect of conifers and climate change on aspen ecosystems and bird reproduction and diversity.

Expected Results:

Already, data show that aspens are biodiversity hotspots for birds, and the study has observed a substantial increase in aspen regeneration following conifer removal. Aspens have declined severely during the past 60 years. Because they depend on deep snow, it is very likely that their decline is associated with climate change at the regional scale. It is expected that conifer encroachment into aspens is detrimental to bird reproduction and diversity due to a decrease in food and increase in nest predation. Nest predators in this system (e.g., squirrels, chipmunks, jays, ravens) are highly associated with conifers. In addition, aspens have higher primary productivity than conifers and likely produce higher insect food loads for birds.

Potential to Further Environmental/Human Health Protection

Managers are proposing a myriad of treatments to restore aspen ecosystems, but many do so with little empirical knowledge of the effectiveness or consequences of these treatments. The experimental removal of conifers from within and around aspens will be able to test the climate’s effect on animal diversity and reproductive success via changes in habitat as well as test the effectiveness of conifer removal at restoring aspen ecosystems. These results could revolutionize the way scientists view habitatbiodiversity relationships and provide a valuable empirical assessment of a management technique to restore aspens. If climate change adversely affects biodiversity and reproductive success in aspens via accelerated conifer encroachment, land managers may choose to remove conifers from existing aspen stands to mitigate these ecosystem impacts.

Supplemental Keywords:

biodiversity, climate change, forest distribution

Progress and Final Reports:

  • 2013
  • 2014
  • Final