Research About riparian

Posted On: Filed Under: Biological Research

Studies of hillslope erosion in the eastern part of the blast zone.

We have been measuring tephra/soil erosion rates in the Smith, Bean, Clearwater, Upper Green River areas of the eastern part of the blast zone. Debris slides and debris flows have been inventoried based on field observations and interpretation of aerial photographs for the 1967 to 1984 period. Sheet and rill erosion was measured with arrays of erosion pins. Repeat photography of hillslope, channel, and revegetation changes has been done at a variety of locations. The intensity of measurements has been reduced through time, but all sites could be revisited and longer-term trends in erosion rates estimated.

 

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Posted On: Filed Under: Biological Research

Recovery of riparian vegetation at Mount St. Helens

This study documents rates and patterns of vegetation recovery at lakes and streams in the blast zone of the May 1980 eruption. Recovery of streamside vegetation was dominated by plants that resprouted from below ground parts that survived the blast. Depending upon frequencies and intensity of secondary disturbances, revegetation from seeds has become increasingly important. Flooding, battering, and deposition of reworked tephra have extremely important effects on streamside revegetation. Recovery rates are more rapid at greater distances from the volcano where blast effects were less devastating.

 

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Survival and growth of native plant species planted in the Mount St. Helens blast area.

The principal objective of this research was to determine the potential of establishing vegetative cover in areas with deep deposits of volcanic materials from the eruptions of Mount St. Helens in 1980 in order to provide for erosion control. Three sites northeast and northwest of the mountain that received approximately 25 cm or more of volcanic materials were studied: two with largely pumice materials and one with predominately fine ash.

 

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Mortality and revegetation of an old-growth forest buried by the Muddy River mudflow

Natural revegetation was studied in an old growth terrace forest buried by 25 to 150 cm of sand to boulder sized material from the Muddy River mudflow. Objectives were: 1) examine patterns of mortality, growth and revegetation along a gradient of mudflow deposition; 2) provide baseline data for future estimates of fragmentation and decay of mudflow killed trees and assess the influence of the dead trees on revegetation processes; 3) establish a 2.5 hectare grid of stem mapped forest to track ecosystem recovery and describe important processes through time.

 

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Riparian/wetland classification for wetlands

The wetland sampling within the Mount St. Helens National Volcanic Monument is part of a larger study on the Gifford Pinchot National Forest. Information gathered will be used to classify riparian/wetland sites into identifiable ecological units that can be used to understand their environmental characteristics and prescribe appropriate management schemes. Study areas in the Monument are Coldwater Lake, Toutle River debris avalanche, and Goat Marsh Research Natural Area. Sample plots were selected to represent different community types (based on species composition and vegetation structure). Wetlands at Coldwater Lake and Toutle River debris avalanche were created as a result of the May 1980 eruption of Mount St. Helens, and thus can provide unique insight into the development of wetlands and plant succession.

 

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Posted On: Filed Under: Biological Research

Riparian/wetland classification for streamsides

The riparian sampling in the Mount St. Helens vicinity is part of a larger study that extends across the Gifford Pinchot National Forest. Streams sampled on the Mount St. Helens Ranger District are Kalama River, East Fork Fossil Creek, and Pin Creek. The purpose of gathering streamside plot data in this project is to produce a classification of streamside vegetative/geomorphic features. The sampling design is such that plant communities are juxtaposed on their geomorphic surfaces and then related to the stream channel itself. Because this project is being carried out in coordination with a separate Forest Riparian Inventory, we will later be able to relate our riparian information to the aquatic data being  collected by the fisheries/hydrology programs.

 

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