Research About blowdown zone

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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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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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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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Effects of May 1980 eruption on soil arthropods — a preliminary look

This preliminary investigation sampled soils in the blast area and blowdown zone in September 1980 for soil arthropods. Predictably, where disruption of pre-eruption ecosystems was most thorough — debris avalanche, pyroclastic flow, blast zone — no soil arthropods survived. In the blowdown zone, by contrast, soil arthropod populations were unaffected largely because they were protected by snow cover at the time of the eruption.

 

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Limnological monitoring of some lakes of the Mount St. Helens National Volcanic Monument.

The monitoring program will sample the phytoplankton and zooplankton communities of Castle and Coldwater Lake. The sampling program will also include water samples which will be analyzed for soluble reactive phosphorus, total phosphorus, nitrate, major ions, dissolved oxygen, and conductivity. Temperature and water transparency will also be observed. The data will be analyzed to determine the structure of phytoplankton and zooplankton communities in these two lakes and the possible impacts of fish introduced into Coldwater Lake.

 

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Post-eruption species selection and planting trials for reforestation of sites near Mount St. Helens

This study monitored survival and growth of seven conifer species planted with shading and fertilization treatments on disturbed sites at Mount St. Helens. Seedlings were planted on six low-elevation sites and five high-elevation sites which represented a variety of post-eruption conditions.

 

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Ant-plant interactions at Mount St. Helens

Within the blowdown zone of Mount St. Helens, Formica pacifica is the most common ant species. From studies during the summer of 1991 patterns were observed in the spatial dispersion of F. pacifica nests and also in the plant species present on the middens of these nests. Formica pacifica is less active within species rich vegetation patches than in exposed areas. Studies in 1992 will investigate whether F. pacifica nests are more common along the edges of vegetation patches. Other studies will investigate the presence of Hypochaeris radicata (false dandelion) on the middens of these nests. The wind born seeds of H. radicata may have difficulty establishing on the nutrient poor tephra. Ant middens may provide suitable sites for these plants to establish. Soil brought to the surface during nest excavation and the collection of plant and insect parts may add nutrients to the substrate of ant middens. Once established above an ant nest, plants would begin to cause shading of the nest. The resulting decrease in temperature may cause the ants to move their nest location. By moving out away from the shade of a vegetation patch and creating more sites for plant establishment, ants of F. pacifica may be effecting the expansion of vegetation patches. Since primary succession at Mount St. Helens is a slow process, the seemingly insignificant effect of ants on this process may be relatively important.

 

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Effects of elk and deer on early forest succession at Mount St. Helens

The objective of this study is to determine the role of elk and deer in the recovery of both natural and managed vegetation following volcanic disturbance. Additionally, we are interested in documenting the influence of elk and deer on vegetation establishment in areas that received different levels of volcanic impact. This goal will be achieved through a network of exclosures that will allow cross-site comparisons.

 

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Population dynamics and habitat ecology of elk in the Mount St. Helens blast zone

Population dynamics and seasonal patterns of foraging behavior of elk in the northwest portion of the Mount St. Helens blast zone were investigated during the years 1982 through 1985. A combination of rapid vegetation regrowth, mild winters, restricted human access and low harvests allowed a rapid re-invasion and recovery of the elk population.

 

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Soil nitrogen along a disturbance gradient.

Soils were studied along a disturbance gradient: Pumice Plain, Timberline parking lot, Harmony, Bismark Mtn., Elk Pass, and Fossil Creek Ridge. N03, NH4, N, P, K, Ca, Mg, C were assayed. NO3 and NH4 were also analyzed from resin bags buried at 15 and 30 cm. Soil samples were collected in 1985. Resin bags were buried for 1 year: 1985 – 86, and 1986 -87.

 

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