Treesearch

Healthy streams play a critical role in supporting plant, fish, and animal communities. However, stream degradation is a global problem that threatens the condition of these important ecosystems. Channel incision is one way that streams can change in response to natural or human processes. This process of degradation leads to lower water tables and a lost connection to the floodplain. As a result, water availability changes for the riparian plant communities, resulting in further degradation.

Field experiments of gap-based silviculture have provided inconsistent evidence that these approaches are effective in regenerating shademidtolerant oaks (Quercus spp.) and hickories (Carya spp.) in upland deciduous forests of the southern Appalachian Mountains, USA.We measured tree regeneration in a long-term field demonstration containing 13- and 30-year-old harvest gaps to evaluate the response of regeneration to group selection harvesting. Oak and hickory regeneration was mapped within the gaps to allow testing for evidence of spatial partitioning among these species. Mixed mesophytic...

In 2020, the COVID-19 pandemic led to the abrupt suspension of cruise ship visits under the U.S. Center for Disease Control’s “No Sail Order” resulting in loss of jobs and revenues for coastal communities of Southeast Alaska. We conducted case studies in three Southeast Alaska communities to learn how they responded to the abrupt loss of cruise tourism and to the economic and social challenges of COVID-19. Through data gathered in focus groups and convenience surveys, we ascertained the strategies that sustained households, businesses, and cultures amid the health threat and economic...

Tree age information is crucial for a range of environmental, scientific, and conservation-related purposes. It helps in understanding and managing forest resources effectively and sustainably. This study presents an approach to estimate tree age across diverse U.S. forested ecosystems using field inventory and climate datasets. The age-size relationship modeling framework incorporates species-specific and environmental variables, enabling its application across various regions. Model R² values range from 0.51 to 0.87 and relative RMSEs (using the mean as the denominator) ranging from 0.14...

The hierarchical model-based (HMB) statistical method is currently applied in connection withNASA’s Global Ecosystem Dynamics Investigation (GEDI) mission for assessing forest aboveground biomass (AGB) in areas lacking a sufficiently large number of GEDI footprints for employing hybrid inference. This study focuses on variance estimation using a bootstrap procedure that separates the computations into parts, thus considerably reducing the computational time required and making bootstrapping a viable option in this context. The procedure we propose uses a theoretical decomposition of the...

Background: Remote sensing techniques for assessing fire severity using two-dimensional imagery, such as satellite data, are limited to a single severity value per pixel, typically at a 30-m resolution. This often leads to an underestimation of understory fire severity, as live tree crowns can obscure the extent of the burned area beneath. By leveraging the three-dimensional capabilities of drone imagery, a more comprehensive assessment of fire severity across different canopy height strata can be achieved.Methods: We show how drone digital aerial photogrammetry (dDAP), also known as...

The mixed estimator (ME) for annual forest inventory proposed by van Deusen (1999; Can. J. For. Res. 29: 1824-1828) is reformulated as a linear mixed model. This equivalent structure admits an interpretation of the ME as a polynomial regression on year with correlated year-specific random effects. It also uncovers the necessary criterion for maximum likelihood (ML) estimation. The improved performance of the ME under ML estimation is illustrated through simulations and application to inventory data from Montana, USA. Limitations of the ME relating to model-misspecification are also discussed.

Site index is frequently used for deciding how to manage stands, however, it often omits or fails to accurately characterize the site-dependent growth of young (ages ≤8 years) trees. This early stage of development is a critical period in a rotation during which important management decisions with the potential to influence all future growth are made. To address this, we developed a new index of site quality for young, coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stands in western Washington, USA. We used high-density light detection and ranging (LiDAR) scans...

Policy makers and planners aim to overcome the “tyranny of small decisions” to address the triple planetary threats of climate change, biodiversity loss, and pollution. However, top-down policies intended to prevent the accumulation of small decisions from undermining collective goods and public infrastructure have removed agency from individuals and caused unintended negative impacts on society. Urban areas are a critical context to examine the role of small decisions because of the extreme diversity and density of decisions and decision-makers within them, their increasing growth...

Conservation entails cultural practices shaped by our worldviews, values, beliefs, and priorities for our interactions with nature. These inform how we categorize which species we want to occur in which landscapes. In Western conservation organizations, conceptualizations of species ‘belonging’ typically align with a dichotomy of native versus introduced species. This is a cultural paradigm, informed by biological considerations, and it is not uniformly shared across different cultures, resulting in varied conceptualizations of species belonging. These conceptualizations may continue to...