Treesearch

Ponderosa pine forests were historically shaped by frequent, low- to mixed-severity fires. Land managers and scientists are concerned that recent high-severity fires, which have left expansive treeless patches in their wake, may prevent ponderosa pine from successfully regenerating in much of its former area. If ponderosa pine does not reclaim these sites, these areas will become grasslands, shrublands, or other forest types, such as aspen or Gambel oak.

Cloud-water interception (CWI) is the process by which fog or cloud water droplets are captured and accumulate on the leaves and branches of plants, some of which drips to the ground. Prior studies in Hawai'i indicate that CWI is highly variable and can contribute substantially to total precipitation. In this study, we monitored CWI and other processes at five mountain field sites on the Islands of Oʻahu, Maui, and Hawaiʻi to explore how CWI (1) varies with different climate and vegetation characteristics, (2) affects plant water use and growth, and (3) contributes to water resources....

Trees can have large effects on soil nutrients in ways that alter succession, particularly in the case of nitrogen-(N)-fixing trees. In Hawai’i, forest restoration relies heavily on use of a native N-fixing tree, Acacia koa (koa), but this species increases soil-available N and likely facilitates competitive dominance of exotic pasture grasses. In contrast, Metrosideros polymorpha (‘ohi’a), the dominant native tree in Hawai’i, is less often planted because it is slow growing; yet it is typically associated with lower soil N and grass biomass, and greater native understory recruitment. We...

Outbreaks of defoliating insects in low-diversity tropical forests occur infrequently but provide valuable insights about outbreak ecology in temperate environments and in general. We investigated an extensive outbreak of the endemic koa moth (Scotorythra paludicola), which defoliated endemic koa trees (Acacia koa) over a third of their range on Hawai‘i Island during 2013 and 2014. At Hakalau Forest National Wildlife Refuge, we observed the dynamics of the outbreak and its effects on host trees, nutrient cycling, and insectivorous consumers in reforestation stands of densely planted koa...

We assessed natural regeneration of longleaf pine (Pinus palustris Mill.) using the data collected from the Escambia Experimental Forest in southern Alabama. Fifteen years after the regeneration control, natural regeneration of longleaf pine remained patchy across a wide range of site and stand conditions; slightly more than half of all plots contained regeneration, but the density of seedlings and saplings varied significantly. The abundance of seedlings ≤1-year-old was positively related to stand age and time since last fire, but negatively related to overstory basal area. The abundance...

Feedbacks within ecosystems can lead to internal reinforcement of the current state providing ecosystem resilience. Often, multiple biotic interactions across trophic levels play a role in such feedbacks, yet these are generally studied independently, obscuring the relative importance of interactions among different factors. We look at various potential feedbacks in intact and degraded mesic forests on Hawaiʻi Island where managers have planted native Acacia koa (koa) trees in an attempt to jumpstart succession in former cattle pastures. These restoration forests, however, have not...

Fire suppression and anthropogenic land use have increased severity of wildfire in western U.S. dry conifer forests. Managers use fuels reduction methods (e.g., prescribed fire) to limit high-severity wildfire and restore ecological function to these fire-adapted forests. Many avian species that evolved in these forests, however, are adapted to conditions created by high-severity wildfire. To fully understand the ecological implications of fuels reduction treatments, we need to understand direct treatment effects and how treatments modulate subsequent wildfire effects on natural communities...

Barestem biscuitroot occurs in the Pacific Northwest of the United States and southern British Columbia (Hitchcock et al. 1961; Lesica 2012). Populations occur on both sides of the Cascade Mountain Range, as far south as central California and Nevada, and as far east as western Utah and Idaho (Hermann 1966; Munz and Keck 1973; Welsh et al. 2016; Hitchcock and Cronquist 2018). Barestem biscuitroot appeared west of the Cascade Range about 4,500 years ago and was likely brought from the high desert interior by the Salish peoples. On Washington’s Waldron Island, barestem biscuitroot is found...

Silverleaf phacelia occurs from British Columbia and Alberta east to the western parts of North Dakota, South Dakota, and Nebraska and south to southern Colorado, Utah, Nevada, and California. It is found in all counties of Utah and Nevada, nearly all counties of Wyoming and Idaho, and all but the coastal areas of Washington, Oregon, and California (USDA NRCS 2021).

Orange agoseris (Agoseris aurantiaca [Hook.] Greene) belongs to the Cichorieae tribe of the Asteraceae family (Lee et al. 2003). NRCS Plant Code. AGAU2 (USDA NRCS 2020).