Treesearch

We monitored instream vertebrate and stream-bank-dwelling amphibian counts during a stand-scale experiment of the effect of riparian buffer width with upland forest thinning in western Oregon, USA using a before/after/control methodology. We analyzed animal counts along 45 streams at 8 study sites, distributed from the foothills of Mount Hood to Coos Bay, Oregon using data collected pre-treatment and during the first decade post-treatment. We examined the role of four types of stream buffers in explaining the variability in post-treatment animal counts. We built separate linear regression...

Key message Deep root hydraulic conductance is upregulated during severe drought and is associated with upregulation in aquaporin activity. Abstract In 2011, Texas experienced the worst single-year drought in its recorded history and, based on tree-ring data, likely itsworst in the pastmillennium. In the Edwards Plateau of Texas, rainfall was 58 % lower and the mean daily maximum temperatures were[5 C higher than long-term means in June through September, resulting in extensive tree mortality. To better understand the balance of deep and shallow root functioning for water supply, wemeasure...

The role of competition in structuring biotic communities at fine spatial scales is well known from detailed process-based studies. Our understanding of competition’s importance at broader scales is less resolved and mainly based on static species distribution maps. Here, we bridge this gap by examining the joint occupancy dynamics of an invading species (Barred Owl, Strix varia) and a resident species (Northern Spotted Owl, Strix occidentalis caurina) in a 1000-km2 study area over a 22-year period. Past studies of these competitors have focused on the dynamics of one species at a time,...

Lodgepole pine (Pinus contorta) forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. Dwarf mistletoe (Arceuthobium americanum) also influences stand structure and occurs frequently in postmountain pine beetle epidemic lodgepole pine forests. Few studies have incorporated both disturbances simultaneously although...

A principal challenge to restoring tree-invaded grasslands is the removal of woody biomass. Burning of slash piles to reduce woody residues from forest restoration practices generates intense, prolonged heating, with adverse effects on soils and vegetation. In this study, we examined vegetation responses to pile burning following tree removal from conifer-invaded grasslands of the Oregon Cascades. We quantified the longevity and magnitude of fire effects by comparing ground conditions and the cover and richness of plant species in burn-scar centers (higher-intensity fire) and edges...

The impacts of escalating wildfire in many regions — the lives and homes lost, the expense of suppression and the damage to ecosystem services — necessitate a more sustainable coexistence with wildfire. Climate change and continued development on fire-prone landscapes will only compound current problems. Emerging strategies for managing ecosystems and mitigating risks to human communities provide some hope, although greater recognition of their inherent variation and links is crucial. Without a more integrated framework, fire will never operate as a natural ecosystem process, and the...

Pervasive forest mortality is expected to increase in future decades as a result of increasing temperatures. Climate-induced forest dieback can have consequences on ecosystem services, potentially mediated by changes in forest structure and understory community composition that emerge in response to tree death. Although many dieback events around the world have been documented in recent years, yellowcedar (Callitropsis nootkatensis) decline provides an opportunity to study vegetation changes occurring over the past century. Current research identifies climate-related reductions in snow...

Paired watershed experiments involving the removal or manipulation of forest cover in one of the watersheds have been conducted for more than a century to quantify the impact of forestry operations on streamflow. Because climate variability is expected to be large, forestry treatment effects would be undetectable without the treatment–control comparison. New understanding of climate variability provides an opportunity to examine whether climate variability interacts with forestry treatments, in a predictable manner. Here, we use data from the H. J. Andrews Experimental Forest, Oregon, USA,...

Analyses of how organisms are likely to respond to a changing climate have focused largely on the direct effects of warming temperatures, though changes in other variables may also be important, particularly the amount and timing of precipitation. Here, we develop a network of eight growth-increment width chronologies for freshwater mussel species in the Pacific Northwest, United States and integrate them with tree-ring data to evaluate how terrestrial and aquatic indicators respond to hydroclimatic variability, including river discharge and precipitation. Annual discharge averaged across...

Analyses of 21 15N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33–50% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the...