Treesearch

One of the first forest genetics studies in the United States launched in 1912 in the Pacific Northwest. Researchers at that time gathered Douglas-fir seeds from various locations in Oregon and Washington, raised the seedlings in a nursery, then transplanted them to places other than where the seeds originated.The results had wide-ranging impact, revealing a link between seed origin and where the resulting seedlings were likely to thrive. These results led to the delineation of “seed zones,” an essential set of guidelines used for decades in reforestation projects to ensure that newly...

This study evaluated the hypothesis that urban-tree planting increases neighborhood gentrification in Portland, Oregon. We defined gentrification as an increase in the median sales price of single-family homes in a Census tract compared to other tracts in the city after accounting for differences in the housing stock such as house size and number of bathrooms. We used tree-planting data from the non-profit Friends of Trees, who have planted 57,985 yard and street trees in Portland (1990–2019). We estimated a mixed model of gentrification (30 years and 141 tracts) including random intercepts...

A wealth of evidence links microbial exposure to better human immune function. However, few studies have examined whether exposure to plant diversity is protective of immune diseases, despite the fact that plant leaves support ~1026 bacterial cells. Using the Centers for Disease Control and Prevention’s 500 cities project data, we found that a 1-SD increase in exposure to taxonomic plant diversity is associated with a 5.3 (95% CI: 4.2–6.4; p < 0.001) percentage-point decline in Census-tract level adult-asthma rate. In contrast, A 1-SD increase in overall greenness exposure (measured using...

Collaborative adaptive management (CAM) is hypothesized to benefit management of rangeland ecosystems, but the presumed benefits have seldom been quantified, and never in a multipaddock rotational grazing system. Here, we evaluated average daily weight gain (ADG) of livestock (kg steer−1 d−1) in four grazing management treatments during the summers of 2016−2018 in a semiarid shortgrass steppe. These four treatments had the same stocking rate but differed in stocking densities. The three lowest stocking densities were implemented using nonadaptive grazing management, while the highest...

In western North America beginning in the late 19th century, fire suppression and other factors resulted in dense ponderosa pine (Pinus ponderosa) forests that are now prone to high severity wildfire, insect attack, and root diseases. Thinning and prescribed fire are commonly used to remove small trees, fire-intolerant tree species, and shrubs, and to reduce surface and aerial fuels. These treatments can be effective at lowering future fire severity, but prescribed burns must be periodically repeated to maintain favorable conditions and are feasible only outside the historical summer...

Shrubs are an important component of terrestrial plant communities in both forested and nonforested ecosystems, but relatively little information is available on their distributions. This project provides mapped occurrences for 78 native shrub species found in the Pacific Northwest (Oregon, Washington, Idaho, and western Montana) as derived from two large regional databases: the U.S. Department of Agriculture, Forest Service Forest Inventory and Analysis database of vegetation collected as part of a nationwide forest inventory and the Consortium of Pacific Northwest Herbaria online...

Although there is widespread support for diversity in natural resources, diversity is valued for different reasons. It is important to understand and critically examine these reasons, to ensure diversity efforts express clear thinking and appropriate motivations. We compiled recent (2000–2019) diversity literature in fisheries, forestry, range, and wildlife, and used a qualitative coding procedure to identify reasons articulated in support of diversity. We developed a subset of these reasons into formal arguments to assess their underlying beliefs and assumptions. Our analysis reveals a...

This report highlights key findings from the most recent 10-year survey of Forest Inventory and Analysis (FIA) data collected across southeast and south-central Alaska and represents the first full remeasurement of all forest plots in the coastal Alaska inventory unit. Estimates of forest area, stand age, volume, aboveground biomass, and carbon are provided across ownerships, forest types, and species throughout the region. Of the 54 million ac in the inventory unit, approximately 15 million ac (28 percent) were considered forest land, most of which is managed by Tongass National Forest in...

Field and laboratory emission factors (EFs) of wildland fire emissions for 276 known air pollutants sampled across Canada and the US were compiled. An online database, the Smoke Emissions Repository Application (SERA), was created to enable analysis and summaries of existing EFs to be used in smoke management and emissions inventories. We evaluated how EFs of select pollutants (CO, CO2, CH4, NOx, total particulate matter (PM), PM2.5 and SO2) are influenced by combustion phase, burn type and fuel type. Of the 12 533 records in the database, over a third (n = 5637) are represented by 23 air...

Nearshore ecosystems (e.g., mangrove forests, sea grass beds, coral reefs) are some of the most biologically diverse and ecologically productive on Earth, while providing essential goods and services to human communities. Because these ecosystems are subject to threats from both land and sea, their conservation and management requires a ridge to reef approach. Here, we developed a watershed decision support tool (DST) for Babeldaob Island, Republic of Palau, aimed at prioritizing catchments for reforestation of fire degraded savanna or protection of native forest against conversion to...