Treesearch

Mixed-conifer forests are widely distributed throughout the mountainous regions of California, occurring just below the upper montane elevation belt and typically ranging from 1,000 to 7,000 ft (300 to 2000 m). Common tree species include ponderosa pine (Pinus ponderosa Lawson & C. Lawson) and Jeffrey pine (P. jeffreyi Balf.), white fir (Abies concolor (Gord. & Glend.) Lindl. ex Hildebr.), sugar pine (P. lambertiana Douglas), incense cedar (Calocedrus decurrens (Torr.) Florin), Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), and black oak (Quercus kelloggii Newberry), and there are...

Chaparral is the dominant vegetation type on dry steep slopes of the national forests in southern California. Chaparral ecosystems are dominated by evergreen fire-adapted shrubs with the ability to recover after fire through fire-stimulated seed germination from a large dormant seed bank or resprouting from unburned root crowns. Despite the resilience of chaparral ecosystems to periodic fire, their integrity is challenged by high frequencies of human-ignited fires, which can occur before resprouting species renew their carbohydrate reserves or regenerating individuals (from seed) reach...

Widespread yet vulnerable, sagebrush (Artemisia spp.) steppe ecosystems provide a variety of biological, hydrological, and recreational ecosystem services throughout the Interior West (Homer et al. 2015). One particular service is the provision of essential habitat for the greater sage-grouse (Centrocercus urophasianus), which was considered for listing under the Endangered Species Act. That listing was avoided in 2015 by an unprecedented conservation partnership across organizations and state boundaries (Chambers et al. 2017). The once widespread sagebrush steppe ecosystem has been...

This report originated from a workshop on long-term postfire ecological restoration held in late 2015 at Yosemite National Park, and a second workshop held at the Natural Areas Conference at the University of California-Davis in late 2016. Workshop attendees included ecologists from the U.S. Forest Service Pacific Southwest Region Ecology Program; scientists from the U.S. Forest Service Pacific Southwest Research Station; and national forest specialists from a variety of fields, including silviculture, soils, and hydrology. In this concluding section, the editors highlight some of the key...

As one of the most dynamic aspects of global environmental change, land cover change (LCC) has a profound impact on terrestrial carbon sequestration. However, LCC-induced carbon fluxes are still the most uncertain terms in global and regional carbon budgets. Ecosystem gross primary production (GPP) is the total carbon uptake by vegetation through photosynthesis, serving as a major control on ecosystem function and land carbon balance during and after the modification of the land surface. However, accurately capturing LCC-induced GPP changes requires both high-quality land cover data and...

Net primary productivity (NPP) and net ecosystem production (NEP) are often used interchangeably, as their difference, heterotrophic respiration (soil heterotrophic CO2 efflux, RSH = NPP-NEP), is assumed a near-fixed fraction of NPP. Here, we show, using a range-wide replicated experimental study in loblolly pine (Pinus taeda) plantations that RSH responds differently than NPP to fertilization and drought treatments, leading to the divergent responses of NPP and NEP. Across the natural range of the species, the moderate responses of NPP (+11%) and RSH (-7%) to fertilization combined such...

Forested wetlands are important in regulating regional hydrology and climate. However, long-term studies on the hydrologic impacts of converting natural forested wetlands to pine plantations are rare for the southern US. From 2005-2018, we quantified water cycling in two post-harvest and newly-planted loblolly pine (Pinus taeda) plantations (YP2-7, 2-7 yrs old; YP2-8, 2-8 yrs old), a rotation-age loblolly pine plantation (MP, 15-28 yrs old), and a natural bottomland hardwood forest (BHF, > 100 yrs old) along the lower coastal plain of North Carolina. We quantified the differences in...

This scoping review compiles 42 published studies measuring children’s attention and/or stress responses to green space settings. Attention and stress outcomes include objective (e.g., physiological) and subjective (rating scale) traditions. Attention studies had two distinct subjective measurement traditions, one measuring ADHD symptoms, the other measuring attention restoration theory constructs. Correlational studies were more likely to use subjective scales for outcomes whereas experimental studies more frequently used objective measures or a mix of objective and subjective measures....

Forest transitions-shifts from deforestation to reforestation-are of increasing interest to scientists and policy-makers due to the importance of forest-related environmental benefits. Forest transitions occur through several pathways, including forest scarcity and economic development, each with different drivers and environmental outcomes. The relative roles of planted forests and natural regeneration in forest transitions are critical but rarely examined. We examined an ongoing forest transition in the USA using county-level data from 1968 to 2017 for 13 southeastern states to analyze...

Over the past century, a variety of environmental stressors, combined with effects from past and current management activities (e.g., fire exclusion, past timber harvest practices, livestock grazing, water diversion), have substantially altered the status of most California ecosystems. These changes include major shifts in ecological disturbance regimes, such as flooding, insect and disease outbreaks, and fire (Barbour et al. 2007, Mooney and Zavaleta 2016). For terrestrial ecosystems, the most profound ecological disturbances are those that substantially increase plant mortality, and in...