Research About subalpine

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Development of vegetation on barren and high elevation sites.

This study is a continuation of work begun in 1980. Current studies include monitoring permanent plots, monitoring grids, studying relict plots, assessing vegetation in potholes, and describing vegetation along transects. The plots studied to date can be divided into those that are fully recovered, those undergoing secondary succession and those undergoing primary succession. The rate of recovery, measured by the number of species and their cover, is related to proximity to sources of colonists and to habitat stress. The species composition of sites undergoing primary succession is related to proximity to intact vegetation and is strongly affected by distance and by chance effects. Previous studies have demonstrated that environmental factors only weakly predict species composition.

 

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Summer bird populations of upper subalpine zone of Mount St. Helens, Mount Adams, and Mount Rainier.

Species composition and abundance of summer birds in the upper subalpine zone of Mount St. Helens were compared to those of Mount Adams and Mount Rainier in order to document these populations as well as to examine effects of the May 1980 eruption on bird populations at the volcano.

 

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Long-term succession in subalpine habitats

A long-term study of recovery and primary plant succession in higher elevations was initiated in 1980. The objectives included to document recovery and invasion in several distinct habitats (e.g. lahars, pumice, blasted ridges, tephra) and to determine the mechanisms of invasion and establishment. In addition, large grids of contiguous 100 m2 quadrats have been established since 1986 in several habitats.
Recovery patterns vary with the size and intensity of the initial impacts. Tephra impacted sites were completely recovered by 1983 and subsequent vegetation change has not been directional. In contrast, intensively impacted sites have recovered much more slowly. Recovery rates differ primarily with the degree of isolation, but the intensity of the impact also governs the recovery rate. For example, lahars surrounded by intact vegetation have acquired as many species as intact vegetation, but community structure remains very different. Total cover after 11 growing seasons remains less than 10% of intact vegetation. Nutrients limit the development of biomass and cover, but most species in the immediate vicinity have established on lahars.

 

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Physiological and population ecology of two subalpine herbs on Mount St. Helens

This study examined the different adaptive strategies of two subalpine herbs in a stressful environment. The study site received tephra in the May 1980 eruption. Polygonum newberryi and Eriogonum pyrolifolium have markedly different morphological characteristics. The former is deciduous and has a large deep root system, the latter is wintergreen and has a shallow root system.

 

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Climate/microclimate measurements over disturbed sites at Mount St. Helens

Climatic and microclimatic measurements for the summers of 1982 to 1987 were made at three differently disturbed sites around Mount St. Helens. These measurements provided daily information on the physical environment and baseline data for studying the evolution and recolonization of these areas.

 

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Recovery of net primary production in subalpine meadows of Mount St. Helens

Study sites that received tephra or mudflow deposits during the May 1980 eruption were examined and compared for effects on vegetation. Deposition of 5-10 cm of tephra resulted in less species diversity and inhibition of seedling establishment but did not significantly decrease net primary production (NPP); the NPP of these areas did fluctuate dramatically with precipitation rates during seven summers from 1980-1986.

 

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The evolutionary ecology of Lupinus lepidus

A four year study of the evolutionary consequences of colonization was begun in 1990. The objectives of this study are to document the pattern of genetic variation in a colonizing plant species, Lupinus lepidus, and investigate the ecological processes which are expected to affect that pattern.

 

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Disturbance and recovery of soil, microbial, and plant processes.

Our work has focused on disturbance and recovery of soil, microbial, and plant processes following volcanic disturbance. Particular emphasis was placed on spatial relationships involving the carbon and nitrogen cycles. Comparative studies have been conducted at six sites that were disturbed to varying degrees by the May 1980 eruption of Mount St. Helens. These sites include Butte Camp, Upper Pine Creek, the Lahar on the Muddy River, the former Timberline parking Area, and Meta Lake.

 

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