Treesearch

Physical dormancy in seeds can challenge restoration efforts where scarification conditions for optimal germination and seedling vigor are unknown. For species that occur along wide environmental gradients, optimal scarification conditions may also differ by seed source. We examined intraspecific variation in optimal scarification conditions for germination and seedling performance in koa (Acacia koa), which occurs across a wide range of environmental conditions. To evaluate scarification responses, we recorded imbibition percentage, germination percentage, germination time, seedling...

Indigenous peoples and local communities (IPLCs) around the world are increasingly asserting ‘Indigenous agency’ to engage with government institutions and other partners to collaboratively steward ancestral Places. Case studies in Hawai‘i suggest that ‘community-driven collaborative management’ is a viable and robust pathway for IPLCs to lead in the design of a shared vision, achieve conservation targets, and engage government institutions and other organisations in caring for and governing biocultural resources and associated habitats. This paper articulates key forms of Indigenous...

The human health and well-being benefits of nature are well-known. The COVID-19 pandemic has disrupted the work of environmental stewardship groups, especially those that facilitate access to and/or provide opportunities to engage with nature. To understand the impacts of this disruption on stewardship groups and their volunteers in Hawai‘i, we: (i) conducted semi-structured interviews with 20 leaders of stewardship groups on O‘ahu; and (ii) surveyed 85 individuals who volunteer with stewardship groups across the state. We found that some groups were negatively impacted by COVID-19-related...

A conceptual framework for climate involvement in forest tree diseases was applied to seven examples to demonstrate its suitability for different disease types: cases where climate favours pathogen biology which then leads to tree mortality or where diseases are caused primarily by climate-driven physiological injury or stress to trees. Hypotheses for climate involvement are derived from detection and monitoring data to express associations of weather or climate factors with disease development at several spatial and temporal scales. Research findings contribute to an understanding of...

Spruce beetle, Dendroctonus rufipennisKirby (Coleoptera: Curculionidae), is a lethal pest of spruce trees in North America. Despite decades of research, a semiochemical repellent that consistently and effectively protects spruce trees remains elusive. We evaluated the efficacy of 3-methyl-2-cyclohexen-1-one (MCH) in a proprietary, volatile compound release technology (SPLAT) alone and with two adjuvants, Acerkairomone blend (AKB) and acetophenone + green leaf volatiles (PLUS) to protect individually treated Picea engelmanniiParry ex. Engelm. (Pinales: Pinaceae), and Pi. engelmanniiwithin...

We examined causes and levels of tree mortality one year after thinning and prescribed burning was completed in ponderosa pine (Pinus ponderosaDougl. ex Laws.) forests at Pringle Falls Experimental Forest, Oregon, U.S. Four blocks of five experimental units (N = 20) were established. One of each of five treatments was assigned to each experimental unit in each block. Treatments included thinning from below to the upper management zone (UMZ) for the dominant plant association based on stand density index values for ponderosa pine followed by mastication and prescribed burning: (1) 50% UMZ...

Forests in the Sierra Nevada and southern Cascade Range are being stressed by a number of factors that put them at risk. High-severity wildfire, drought stress, insect outbreaks, disease, and a backdrop of changing climate all pose a threat to the persistence of these forests. These factors can work individually or combine to magnify the impacts on forests. For example, the 2012–2016 drought led to tree stress that increased susceptibility to bark beetles. However, there are land management options that can help landowners increase forest health. A significant portion of Sierra Nevada and...

Yellow pine and mixed-conifer (YPMC) forests are common forest types in northwestern California and southwestern Oregon (the “assessment area”). YPMC forests occur above oak woodland and mixed-evergreen forests and below red fir forests, and are dominated by diverse combinations of ponderosa pine (Pinus ponderosa Lawson & C. Lawson), Jeffrey pine (P. jeffreyi Balf.), incense cedar (Calocedrus decurrens (Torr.) Florin), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), white fir (Abies concolor (Gord. & Glend.) Lindl. ex Hildebr.), and sugar pine (P. lambertiana Douglas) with a notable...

In the Klamath River Basin (KRB) of northern California and southern Oregon, climate-related changes, such as more intense droughts, varied and concentrated precipitation, earlier spring and later fall conditions, extreme temperatures, and decreased snowpack have contributed to increasingly unpredictable plant reproduction and harvest cycles. In this study, we explore contemporary relationships between plants and Indigenous People in the KRB, identifying benefits of cultural ecosystem services (CES) derived from Indigenous stewarding and gathering of culturally significant plants, and...

Exposure to ozone pollution has serious health risks. Damage to lungs and impairment of cardiovascular health are of particular concern for vulnerable populations, including children, the elderly, and individuals from “disadvantaged” communities whose health may already be compromised. This report describes three successive studies that led to the development of techniques for directly monitoring human exposure to ozone. Experiment 1 was a proof of concept and exploration of potential systematic errors. Experiment 2 was a more extensive use of personal monitoring to evaluate differences in...