Biological Research

Posted On: Filed Under: Biological Research

Effect of herbivores on Sitka willow and associated plant and animal communities and soils.

The invasion of trees and shrubs in early succession is often transformative because of their potential to outcompete early pioneers, provide animal habitat, influence nutrient cycling, and occupy sites over long time spans. The extent to which insect herbivores influence such successional transitions is unknown. We are investigating whether herbivory by a pair of stem-boring insects may substantially impede the structural dominance of Salix sitchensis, the first abundant woody colonist on a large primary successional site at Mount St. Helens volcano, Washington, USA. We also quantify vegetation and soil development at these same sites. Our collaborator Charlie Crisafulli (USFS) quantifies bird use of these sites, eventually allowing us to link herbivore effects on vegetation to bird habitat.

 

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Posted On: Filed Under: Biological Research

Current Vegetation Survey (part of national vegetation mapping program)

Long term vegetation sampling for monitoring and current conditions. Permanent one hectare plots are installed every 1.7 miles in a grid pattern, to be remeasured in an 8-10 year cycle. Above ground vegetation is tallied, numbered, and referenced, where available; shrubs, herbs, forbs species and crown cover are estimated on five 1/20th acre subplots. Down woody debris is tallied using five 51.1’ line transects. Objective is condition database and remeasurability. Locations will also be used to tally lichens, wildlife, etc. on other studies.

 

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Posted On: Filed Under: Biological Research

Dynamic Spatial Patterns During Succession: Resolving Patterns and Mechanisms using Grid-Based Spatial Automata Models

(Project Summary from NSF Research Grant). Our major objective is to investigate how the spatial relationships among individual plants contribute to successional dynamics and influences the spatial patterns that result. We propose to investigate the effects of spatial interactions at the individual level on population dynamics and ecosystem succession on the Pumice Plain near Mount St. Helens, Washington. Spatial analyses of annual field survey data will test the significance of number, size, and species of neighboring plants on growth, survival, and recruitment. Computer models using grid-based spatial automata will implement alternative life histories and individual-level interactions to simulate spatial dynamics during primary succession. The results of this study will provide insights into integration of spatial dynamics across three levels of ecological organization: at the individual level, spatially modified growth rates; at the population level, spatially modified recruitment and mortality; at the ecosystem level, dynamic spatial patterns during succession.

 

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Posted On: Filed Under: Biological Research

Changes in the lakes within the Mount St. Helens blast zone

We will study changes in two lakes (Meta and Ryan) since the blast. Analysis will consist of analyzing physical and chemical properties of soils and entering these data into a GIS to model the amount of runoff in each watershed. The other focus will look at nutrients and plankton within each lake and conducting experiments to determine the effects of different levels of nutrients and predation on the plankton.

 

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Posted On: Filed Under: Biological Research

Insect colonization and invasion in the recovering devastation zone of Mount St. Helens.

Vegetation patches at Mount St. Helens represent discrete islands that are a focus for interactions among plants and insects. Our continuing studies focus on the role of biotic interactions (plant-herbivore and predator-prey), dispersal, and disturbance in this highly fragmented landscape. In the 1997 field season, we aim to address two primary questions: 1) What factors have allowed exotic ladybird beetles to displace native ladybird species within the monument? and 2) How does the size of vegetation patches influence colonization by insect species?

 

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Posted On: Filed Under: Biological Research

Influence of Debris Avalanche Block Faces and Mixed Facies on the Evolution of the North Fork of the Toutle River Drainage (1980-Present), Mount St. Helens, WA

An integrated field and laboratory-based study is outlined that proposes the role that sedimentary, geomorphic, and vegetative variables have played in the recovery on the North Fork of the Toutle River (NFTR) following the May 18, 1980 eruption of Mount St. Helens. The abundant volcaniclastic detritus produced by this eruption temporarily overwhelmed drainage systems flowing from the crater including the NFTR. The sedimentary detritus delivered to the upper reaches of the NFTR including debris avalanche facies has had a profound effect on the Morpho-sedimentary character of this drainage system. Planning and hazard evaluation along the North and South Forks of the Toutle River as well as the main Toutle River depend upon a clear understanding of sediment balance within the stream system. Data gathered during the duration of this project will extend understanding of that balance by quantifying the relative contributions of volcanogenic sedimentary detritus from prominent source deposits.

 

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Posted On: Filed Under: Biological Research

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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Posted On: Filed Under: Biological Research

Mechanisms of vegetation change following burial by volcanic tephra

This project continues detailed study of forest understory vegetation change after burial by tephra from Mount St. Helens in 1980. Objectives are to provide a detailed record of pathways of change; to record spatial and temporal variation in soil properties; to determine species characteristics important for recovery from burial; and to use these data to determine the mechanisms of succession. Data will be analyzed to compare responses of different growth forms, species and communities in different conditions of tephra depth, seral age, and time of tephra removal. This study will provide a long-term set of consistent, detailed data about vegetation recovery from an important, widespread disturbance.

 

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Posted On: Filed Under: Biological Research

Tree ring dating of prehistoric eruptions of Mount St. Helens

This study includes two topics: 1. Dating of prehistoric eruptions of Mount St. Helens using tree ring patterns of living trees and of dead, buried trees. Using increment cores of Douglas fir (Pseudotsuga menziesii), three prehistoric eruptions were dated at 1480, 1482, and 1800 A.D.   View the full abstract (69A)

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Posted On: Filed Under: Biological Research

Patterns and mechanisms of early plant primary succession on the pumice plain.

Primary colonists and mechanisms of their arrival to the pumice plain have been monitored since 1986. Measurements of seed rain have shown that the most common wind dispersed species arriving on the pumice plain are Anaphalis margaritacea, Epilobium angustifolium, and E. watsonii. Of the early colonists A. margaritacea is the most wide spread species, but Lupinus lepidus is the most abundant species. In addition the L. lepidus population is increasing dramatically.

 

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