Life Sciences Commons^™

Non-Random Sampling Measures The Occurrence But Not The Strength Of A Textbook Trophic Cascade, Daniel R. Macnulty, Elaine M. Brice, Eric J. Larsen

Wildland Resources Faculty Publications

Although sampling the five tallest young aspen in a stand is useful for detecting the occurrence of any aspen recruitment, this technique overestimates the population response of aspen to wolf reintroduction. Our original conclusion that random sampling described a trophic cascade that was weaker than the one described by non-random sampling is unchanged.

Decline Of An Ecotone Forest: 50 Years Of Demography In The Southern Boreal Forest, Joseph D. Birch, James A. Lutz, E. H. Hogg, Suzanne W. Simard, Rick Pelletier, George H. Laroi, Justine Karst

Wildland Resources Faculty Publications

Variation in tree recruitment, mortality, and growth can alter forest community composition and structure. Because tree recruitment and mortality events are generally infrequent, long‐time scales are needed to confirm trends in forests. We performed a 50‐yr demographic census of a forest plot located on the southern edge of the Canadian boreal forest, a region currently experiencing forest die‐back in response to direct and indirect effects of recent severe droughts. Here, we show that over the last 30 yr biomass, basal area, growth, and recruitment have decreased along with a precipitous rise in mortality across the dominant tree species. The stand …

Continental-Scale Assessment Of Genetic Diversity And Population Structure In Quaking Aspen (Populus Tremuloides), Colin M. Callahan, Carol A. Rowe, Ronald J. Ryel, John D. Shaw, Michael D. Madritch, Karen E. Mock

Wildland Resources Faculty Publications

Aim: Quaking aspen (Populus tremuloides) has the largest natural distribution of any tree native to North America. The primary objectives of this study were to characterize range-wide genetic diversity and genetic structuring in quaking aspen, and to assess the influence of glacial history and rear-edge dynamics.

Location: North America.

Methods: Using a sample set representing the full longitudinal and latitudinal extent of the species’ distribution, we examined geographical patterns of genetic diversity and structuring using 8 nuclear microsatellite loci in 794 individuals from 30 sampling sites.

Results: Two major genetic clusters were identified across the range: a southwestern cluster and …

Aspen Succession And Nitrogen Loading: A Case For Epiphytic Lichens As Bioindicators In The Rocky Mountains, Usa, Paul C. Rogers, Kori D. Moore, Ronald J. Ryel

Wildland Resources Faculty Publications

Question: Can lichen communities be used to assess shortand long-term factors affecting seral quaking aspen (Populus tremuloides) communities at the landscape scale? Location: Bear River Range, within the Rocky Mountains, in northern Utah and southern Idaho, USA. Method: Forty-seven randomly selected mid-elevation aspen stands were sampled for lichens and stand conditions. Plots were characterized according to tree species cover, basal area, stand age, bole scarring, tree damage, and presence of lichen species. We also recorded ammonia emissions with passive sensors at 25 urban and agricultural sites throughout an adjacent populated valley upwind of the forest stands. Nonmetric multidimensional scaling (NMS) …