Treesearch

Diel fluctuations can comprise a significant portion of summer discharge in small to medium catchments. The source of these signals and the manner in which they are propagated to stream gauging sites is poorly understood. In this work, we analysed stream discharge from 15 subcatchments in Dry Creek, Idaho, Reynolds Creek, Idaho, and HJ Andrews, Oregon. We identified diel signals in summer low flow, determined the lag between diel signals and evapotranspiration demand and identified seasonal trends in the evolution of the lag at each site. The lag between vegetation water use and streamflow...

Forest encroachment threatens the biological diversity of grasslands globally. Positive feedbacks can reinforce the process, affecting soils and ground vegetation, ultimately leading to replacement of grassland by forest species. We tested whether restoration treatments (tree removal, with or without fire) reversed effects of nearly two centuries of encroachment by Abies grandis and Pinus contorta into dry, montane meadows in the Cascade Range, Oregon, USA. In nine, 1-ha plots containing a patchy mosaic of meadow openings and forests of varying age (20 to .140 yr), we compared three...

Bedrock groundwater dynamics in headwater catchments are poorly understood and poorly characterized. Direct hydrometric measurements have been limited due to the logistical challenges associated with drilling through hard rock in steep, remote and often roadless terrain. We used a new portable bedrock drilling system to explore bedrock groundwater dynamics aimed at quantifying bedrock groundwater contributions to hillslope flow and catchment runoff. We present results from the Maimai M8 research catchment in New Zealand and Watershed 10 (WS10) at the H.J. Andrews Experimental Forest in...

Nothing standing aboveground today was here thirty years ago. The ground itself wasn't here. Oh, there was ground, but much of it lay below the surface where my boot soles slip a little in the loose pebbles of pumice. Rolling on loose rock and big ideas, for a moment I lose my sense of balance, glancing first at the sky above, then at the nearby peak of Mount St. Helens as if to stabilize myself.

Initial field releases of the saltcedar leaf beetle, Diorhabda carinulata Desbrochers, 1870 (Chrysomelidae), against saltcedars, Tamarix Linneaus, 1753 (Tamaricaceae) in North America were unsuccessful at sites where the target taxon was T. parviflora de Condolle, 1828 as opposed to the more widespread T. ramosissima Ledebour, 1829 and related forms. A series of field and greenhouse studies was conducted to determine the basis for these failures. Generally, T. parviflora was a suitable host for larval and adult development. Larval growth was not significantly affected by host species...

In many regions of the world, the extremes of winter cold are a major determinant of the geographic distribution of perennial plant species and of their successful cultivation. In the United States, the U.S. Department of Agriculture (USDA) Plant Hardiness Zone Map (PHZM) is the primary reference for defining geospatial patterns of extreme winter cold for the horticulture and nursery industries, home gardeners, agrometeorologists, and plant scientists. This paper describes the approaches followed for updating the USDA PHZM, the last version of which was published in 1990. The new PHZM...

Although field-collected recordings typically contain multiple simultaneously vocalizing birds of different species, acoustic species classification in this setting has received little study so far. This work formulates the problem of classifying the set of species present in an audio recording using the multi-instance multi-label (MIML) framework for machine learning, and proposes a MIML bag generator for audio, i.e., an algorithm which transforms an input audio signal into a bag-of-instances representation suitable for use with MIML classifiers. The proposed representation uses a 2D...

Limber pines are one of the most picturesque trees in Rocky Mountain National Park (RMNP). Growing in some of the park's most exposed rocky sites, the trees' gnarled trunks give testimony to fierce winds that buffet them in winter. Limber pines live to great ages, with some in the park exceeding 1,000 years. An especially photogenic stand of ancient trees defies the wind at Knife's Edge along Trail Ridge Road, and a remarkable old giant stands sentinel on the shore of Lake Haiyaha. Although the species occurs in small stands dominating only about 2,700 acres of the park, limber pine is an...

The majority of the world's forests are used for multiple purposes, which often include the potentially conflicting goals of timber production and biodiversity conservation. A scientifically validated management approach that can reduce such conflicts is retention forestry, an approach modeled on natural processes, which emerged in the last 25 years as an alternative to clearcutting. A portion of the original stand is left unlogged to maintain the continuity of structural and compositional diversity. We detail retention forestry's ecological role, review its current practices, and summarize...