The physical controls of snowmelt in the Pacific Northwest (PNW) are poorly
understood. While there have been numerous field and modeling investigations at the
plot and watershed scale, few studies have identified how the snow energy balance
(EB) components vary in importance both spatially and temporally. The identification
of how...
The age, or residence time of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways and source of water in a single integrated measure. While there has been tremendous recent interest in residence time to characterize catchments, there are few studies that quantify residence...
The arthropod community in a Douglas-fir forest near Blue River, Lane County, Oregon was investigated from March through August 1973. Five stands of Douglas-fir were sampled: two clearcuttings, a young-growth
(20 years old), a midgrowth (125 years old), and an old-growth (450 years old) plot. A pole pruner was used...
Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape and have contracted by over 50% in the past two hundred years in the HJ Andrews Experimental Forest (hereafter Andrews...
Nineteen l/4-hectare reference stands have been established in the central western Cascade Mountains of Oregon to represent widespread and important portions of the vegetation continuum. Their species diversity, cover, and structure are described here. The stands provide points of reference for visiting scientists and researchers who wish to design experiments...
Bioassays using red alder and snowbrush plants grown in soils collected
from a clearcut, a young Douglas-fir plantation, and an old-growth stand were
conducted. Sites are located at the Andrews Experimental Forest, Oregon. In
the first bioassays, more alder than snowbrush plants survived and nodulated.
Of the plants that survived,...
Ectomycorrhizal fungi (EmF) form symbioses with trees. These symbioses profoundly influence forest ecology. Certain EmF form specialized profusions of hyphae, known as ectomycorrhizal fungal mats (mats) which are visible to the naked eye, alter forest soil biogeochemistry, substantially contribute to soil microbial biomass/respiration and support unique microbial communities. Piloderma and...
A biological inventory of the butterflies of the H. J. Andrews Experimental Forest [HJA] in Linn/Lane County, Oregon was conducted during 1994 and 1995. It was the first comprehensive survey of HJA butterflies for the site and serves as a baseline for future butterfly research. A detailed ecological account is...
In recent years considerable interest has been shown in the diversity of ammonia-oxidizing bacteria in soil communities. The majority of the research has been carried out in Northern Europe where soils have received high atmospheric inputs of nitrogen over the past two centuries. In contrast, although much work has been...
Windthrow has been studied extensively as a cause of mortality and as a landscape
disturbance agent in temperate forests throughout the United States. The effects of
windthrow mortality on stand species composition and structure, forest regeneration and
seral development have been well described at the site (e.g. single gap) and...
The links between forests, streamflow, and climate are poorly understood. Despite hundreds of studies over the past 60 years, fundamental questions of forests' effects on the hydrologic cycle remain unanswered. The hydrological cycle involves mutually-dependent biological and physical processes that operate at multiple scales of time and space, and this...
This study investigated carbon dynamics in the hyporheic zone of a steep, forested catchment in the Cascade Mountains of western Oregon, USA. Water samples were collected monthly from a headwater stream and well network during baseflow conditions from July to December 2013 and again in March 2014. We also sampled...
For management purposes, it would be useful to be able to predict streamflow response to forest practices in small, unmonitored basins. The primary objective of this study is to investigate the influence of early successional vegetation on summer streamflow levels. The long-term data records from watershed 1 at the H.J....
Headwater streams are an integral part of the ecological health of the greater stream network as they provide valuable biological habitat, provide upwards to 95% of total in channel flow, while providing downstream reaches with important constituents such as sediment and woody debris. Small headwater streams are particularly susceptible to...
Soil dissolved organic carbon (DOC) is a small but crucial part of the forest carbon cycle. Characterizing the relationship between detrital inputs and soil DOC chemistry is crucial to understanding the ultimate fate of root carbon, fallen wood and needles. Chemical differences in the DOC pool may help to explain...
Despite advances in the understanding of rain-on-snow storms and their resulting peak flows, little is understood about the response of snowmelt to precipitation and the relative timing of the two at multiple temporal scales within such events. To address this issue, climate, snowmelt, and streamflow data were analyzed for 26...
Montane meadows in the Cascade Range of Oregon have been declining due to tree establishment since records began. Montane meadow complexes in the H.J. Andrews Experimental Forest shrank by 60 to 75% from 1949 to 2005, but fine scale temporal and spatial processes of tree establishment in these meadows are...
The link between aboveground net primary productivity (ANPP) and resource gradients generated by complex terrain (solar radiation, nutrients, and moisture) has been established in the literature. Belowground ecosystem stocks and functions, such as soil organic carbon (SOC), dissolved organic carbon (DOC), and belowground productivity have also been related to the...
This study examined how annual bedload export volume and bedload characteristics were related to disturbances including logging, floods, debris slides, and wildfires over 48 to 65-year periods in small, steep catchments in conifer forests of the western Cascade Range, Oregon. Bedload – the material rolling, sliding, or saltating along the...
Streams and rivers play a critical role in global carbon (C) cycling by processing, storing, and transporting C. Headwater streams which make up more than 95% of the length of streams and rivers worldwide have disproportionate influence on fluvial C dynamics. The hyporheic zone (HZ) of headwater streams is a...
We present a systems modeling approach to the development of a place-based ecohydrological model. The conceptual model is calibrated to a variety of existing observations, taken in watershed 10 (WS10) at the HJ Andrews Experimental Forest (HJA) in Oregon, USA, a long term ecological research (LTER) site with a long...
Population trends and patterns in species distributions are the major currencies used to examine responses by biodiversity to changing environments. Effective conservation recommendations require that models of both distribution dynamics and population trends accurately reflect reality. However, identification of the appropriate temporal and spatial scales of animal response, and then...
Field and laboratory studies are being conducted to describe the hydrologic properties of soil and to determine the timing pathway of precipitation and snowmelt water as it moved through forested soil on a steep slope. Hydrologic properties include hydraulic conductivity, porosity, pore-size distribution, moisture characteristics, stone content, and soil depth....
Most carbon (C) transformations in soil are carried out by a diverse and complex soil microbial community. The size and composition of the soil microbial community is determined by poorly understood interactions between the quantity and chemical composition of plant inputs, as well as climate. Given the metabolic diversity of...
This report describes decomposition studies conducted in the H. J. Andrews
Forest, Oregon in 1973. Changes in weight loss and nutrient content of
leaves, cones, branches, and bark of Douglas-fir and leaves of big-leaf
maple, vine maple, Rhododendron, red alder, sword fern Oregon oak, and
Chinkapin were recorded in a...
Air temperatures at i m and soil temperatures at 2C cm are reported for
twenty-one forest stands in the central Western Cascader of Oregon. Records
began in 1970 for some stands, in 1971 or 1972 for most. Temperature Growth
Index for a stand, based on temperature effects on Douglas-fir seedling...
A total of 23 forest communities have been identified and characterized in a preliminary manner. Data used in formulating the classification had previously been collected on 300 reconnaissance plots located on the
H. J. Andrews Forest and surrounding area. Vegetation classification was facilitated by similarity analysis and stand ordination procedures...
Sediment yield increases following timber harvest and road construction
were predicted for four Pacific Northwest experimental
watersheds. Sediment yields were predicted using a handbook developed
by the U.S. Forest Service entitled, "An Approach to Water Resources
Evaluation of Non-Point Silvicultural Sources" (WRENS). Predicted
sediment yield increases varied from 40 to...
Populations of mites and.nematodes were monitored on Watershed 10, H. J.
Andrews Forest. A minimum of 50 families and 60 genera of mites are
present, the majority being Cryptostgmata. Population estimates vary
from 5000-350,000 per square meter. Nine categories of nematodes are
present, most belonging to the saprozoic, dorylaimoid, aquatic...
Early in the planning of the Coniferous Biome program It was recognized that experimental watersheds 2 and 3 in the H. J. Andrews Experimental Forest might provide ideal study sites for certain phases of the Biome
program. A study was funded during year 1 (1970) to provide necessary background ecological...
It is becoming increasingly important to understand fundamental hillslope-scale hydrological processes. Most hillslope-sale transport experiments have generally focused on conceptual findings or other aspect of flow behavior, rather than the quantification of the mass transport mechanisms of advection and dispersion. When the velocities have been quantified, dispersion has been mentioned...
Although the Pacific Northwest has the least proportion of non-native plant species in relation to other regions of North America, exotic species continue to spread into mountainous areas, including the Cascade Range. In a forested landscape, road networks can act as corridors for exotic plant dispersal and establishment, helping species...
We examined the spatial and temporal variability of stream carbon dioxide (CO₂) and the drivers of these variations in a headwater catchment. To examine temporal variation and drivers, we measured stream and hyporheic pCO₂ at high temporal resolution over 11 months in a 95.9-ha forested headwater catchment in the Western...
The objective of this research was to assess the variability of POP deposition by snow on a 10 km spatial scale by measuring the POP concentrations in fresh-fallen snow from remote alpine sites. Samples of pre-metamorphic snow were concurrently collected from three remote alpine sites, of matched altitude and exposure,...
The mechanisms governing short- and long-term belowground carbon dynamics need to be understood. As part of a larger project developed to assess the effect of quantity and quality of litter inputs on the rate of soil organic matter (SOM) formation, I examined SOM in the H. J. Andrews Detritus Input...
In undisturbed N-limited forested catchments, DON may represent over 90% of the total N lost in streams. Some ecologists have suggested that plant-derived reactive polyphenols may be responsible for DON binding and transport because polyphenol-protein complexes are known to precipitate out of solution, bind to mineral surfaces or organic matter...
This dissertation was undertaken to improve the understanding of the population dynamics of the Pacific Golden chanterelle, Cantharellus formosus. It addresses the longevity of individuals over a 12 year period and the limits of gene flow within the area of a 6,400 hectare watershed at the H.J. Andrews Long Term...
Ectomycorrhizal (ECM) fungi of the genera Piloderma and Ramaria form dense hyphal mats in the organic and upper mineral soil layers, respectively, in coniferous forest floors of the Pacific Northwest. Previous studies have determined that fungal mats change the chemical, physical, and biological properties of the soil within. Little information...
This study examines the long-term role of interference on stand development of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and red alder (Alnus rubra Bong.) planted mixtures in the Central Cascades of Oregon, USA. The two species are common associates in naturally regenerated and planted conifer stands in the Pacific Northwest. Due...
The specific objectives of this dissertation are to determine subsurface flow
behaviors across different antecedent wetness conditions from a top-down perspective
and to mechanistically assess the hydrological controls on DOC and N transport at the
hillslope and catchment scale. The study area is a small catchment where hillslopes
issue directly...
A simple debris-slide model, employing a digital elevation model (DEM) and geological data, was used in a geographic information system (GIS) to map slope stability in the Andrews Experimental Forest, located in the western Cascade Range in Oregon, USA. To evaluate the contribution of error in elevation to the uncertainty...
Seasonal and annual patterns of N fluxes and concentrations in streamwater in six conifer-dominated watersheds at the H.J. Andrews Experimental Forest, OR, were studied to gain insight into the factors that influence N retention in this ecosystem. Processes affecting N flux in streamwater differed between organic (DON) and inorganic (DIN;...
Soil organic matter (SOM) is the terrestrial biosphere's largest pool of organic carbon (C) and is an integral part of C cycling globally. Soil organic matter composition typically can be traced directly back to the type of detrital inputs; however, the stabilization of SOM results as a combination of chemical...
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Bousson ExperimentalForest, PA, USA .................................. 6
H. J. Andrews
Early in the planning of the Coniferous Biome research program, it was recognized that Experimental Watersheds 6, 7, and 8 in the
H. J. Andrews Experimental Forest might provide ideal study sites for certain phases of the Biome program. A study was funded during year 1 (1970) to provide necessary...
This project explores mechanisms governing the invasion of fluvial systems by two
contrasting exotic species in stream networks of steep, relatively remote forested landscapes
of western Oregon. This research addresses hypotheses relating limitations of seed source
locations, seed transport processes, and sink availability to the distributions of scotch broom
(Cytisus...
Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming are hampered by uncertainty in the ability of the earth’s ecosystems to counteract this effect by sequestering carbon...
Studies in the lower Lookout Creek-Blue River area have revealed a geomorphic history including glaciation and the development of three alluvial surfaces, presently active alluvial cones and older, deeply dissected cone remnants. Results are based on landform mapping, analysis of the types and distributions of surficial sediments, and the
distribution...