Treesearch

In North America, a comparatively small number of Fraxinus (ash) cultivars were planted in large numbers in both urban and rural environments across the entire range of Fraxinus pennsylvanica Marsh (green ash) over the last 80 years. Undetected cultivar gene flow, if extensive, could significantly lower genetic diversity within populations, suppress differentiation between populations, generate interspecific admixture not driven by long-standing natural processes, and affect the impact of abiotic and biotic threats. In this investigation we generated the first range-wide genetic assessment...

Forests worldwide are experiencing increasingly intense biotic disturbances; however, assessing impacts of these disturbances is challenging due to the diverse range of organisms involved and the complex interactions among them. This particularly applies to invasive species, which can greatly alter ecological processes in their invaded territories. Here we focus on the pine wood nematode (PWN, Bursaphelenchus xylophilus), an invasive pathogen that has caused extensive mortality of pines in East Asia and more recently has invaded southern Europe. It is expected to expand its range into...

The oak twig pruner [OTP; Anelaphus villosus (Fabricius)] is likely a species complex, with A. parallelus (Newman) recently recognized as a synonym. The parallelus form of A. villosus is considered the subject of this paper. In Michigan, OTP has a 2-year life cycle, with twigs pruned primarily in even-numbered years and adults emerging from the fallen twigs in odd-numbered years. During 1990 to 2011, I studied various aspects of OTP life history in southern Michigan (Ingham County). Based on measurements from over 300 infested oak twigs, they averaged 43.1 cm long, 9.4 mm in diameter at...

Natural ecosystems store large amounts of carbon globally, as organisms absorb carbon from the atmosphere to build large, long-lasting, or slow-decaying structures such as tree bark or root systems. An ecosystem’s carbon sequestration potential is tightly linked to its biological diversity. Yet when considering future projections, many carbon sequestration models fail to account for the role biodiversity plays in carbon storage. Here, we assess the consequences of plant biodiversity loss for carbon storage under multiple climate and land-use change scenarios. We link a macroecological...

A tamarack [Larix laricina (Du Roi) K. Koch] provenance plantation, consisting of 33 seed sources from the United States and Canada, was established in 1969 in southern Michigan (Kalamazoo County). About half of the trees were removed in fall 1984 when the stand was thinned, with the cut trees piled on the edge of the stand. The stand then experienced a severe ice storm in January 1985. The eastern larch beetle, Dendroctonus simplex LeConte, colonized the cut logs in 1985 and also infested many of the standing trees. By the end of 1986, over half the remaining trees had been killed by D....

Myotis septentrionalis (Northern Long-eared Bat) has recently suffered a >90% decline in population size in North America due to white-nose syndrome (WNS). We assessed genetic diversity, population structure, current effective population size, and demographic history of M. septentrionalis distributed across the United States to determine baseline levels pre-WNS. We analyzed RADseq data from 81 individuals from Kentucky, Louisiana, Michigan, Minnesota, North Carolina, Oklahoma, and Wisconsin. Additionally, we examined population genetic structure using discriminant analysis of principal...

We evaluated shoot nonstructural carbohydrate (NSC) concentrations, stem wound closure, and radial growth of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) trees in a novel ice storm experiment in which five storm treatments (0, 6.4, 12.7, and 19.1 mm of radial ice accretion in 1 year and 12.7 mm of ice in two consecutive years) were applied within a mature northern hardwood forest. We tested for changes in physiology at two levels: (1) associated with plot-level ice treatments and (2) with crown damage classes of individual trees. Few differences in NSC or wound...

Background: Reducing Emissions from Deforestation and forest Degradation (REDD+) is a program established under the United Nations Framework Convention on Climate Change (UNFCCC) to reduce carbon emissions from forests in developing countries. REDD+ uses an incentive-based approach whereby participating countries are paid to reduce forest carbon loss and increase carbon storage. Country-level carbon accounting is challenging, and estimates of uncertainty in emission reductions are increasingly required in REDD+ reports. This requirement is hard to meet if countries lack the necessary...

Trees are exposed to a variety of stressors over their lifetimes. To survive and thrive under diverse conditions, they have evolved a suite of defenses, which confer resistance or tolerance to most biotic and abiotic stressors. Even though disease (or insect pest infestation) is the exception and not the rule, pests and pathogens have had and continue to have a profound impact on the health of forests globally. This is especially true for invasive and/or non-native pests and pathogens and, more recently, for native pests and pathogens whose range or virulence has changed because of climate...

Prior research has indicated lower crime rates in areas with greater tree canopy cover predominantly in the Global North. There are few studies from the Global South, and more specifically in Latin America. Given the high prevalence of crime in Latin American cities, the need to address social and environmental inequalities using nature-based solutions is urgent. This study examines crime and tree canopy cover through a series of spatial analyses for São Paulo city, Brazil, while controlling for potential confounders. We tested six levels of data aggregation that were combined with three...