Advisor: Michael Bozek
Riparian vegetation and stream temperature relationships; opportunities for trout management
Summer
water temperature limits the length of streams providing
suitable brook trout (Salvelinus fontinalis) habitat in Wisconsin’s
North Central Hardwood Forests Ecoregion. Formerly dominated by riparian
hardwood forests, European settlement and sequential land-use actives
such as logging, grazing, agriculture activities, and urbanization have
led to considerable alterations of riparian areas and resulted in warmer
stream temperature regimes. The heating of streams is the result of
complex interactions of air temperature, relative humidity, wind speed,
ground water input, solar radiation, stream width,depth, and velocity. Shade, provided by riparian vegetation, reduces solar radiation and may promote opportunities to decrease water temperatures in thermally marginal habitats. Much of Wisconsin’s current trout stream habitat management focus on implementing in-stream structures and bank stabilization, beaver dam removal, and streambank debrushing even though these activities have resulted in questionable success rates in trout habitat improvement. Additionally, many of these habitat management techniques require future maintenance or they will degrade requiring some costs for continued upkeep.
Planting trees in riparian areas or just allowing succession to take place
eventually leading to trees in areas suitable for them will result in
stable stream banks, as well as increases in stream shading, coarse
woody debris habitat, and allochthonous material for secondary
production. Managing streams this way could prove to be very productive,
sustainable, and cost efficient. A key research gap involves
understanding how much downstream brook trout habitat is being lost due
to increased summer water temperatures. This study will calibrate a
stream temperature model to Wisconsin’s North Central Hardwood Forests
Ecoregion streams based on varying riparian vegetation treatments and
subsequently use this model to predict the amount of stream capable of
supporting brook trout populations based on known thermal preferences.
This model will be used to predict potential brook trout habitat
gains/losses due to manipulation of riparian vegetation and shade.
Current types of riparian vegetation and their influences on stream
temperature change will be quantified in order to gain more insight into
how riparian vegetation management could influence stream temperature
change in Wisconsin’s North Central Hardwood Forests Ecoregion. Managing
for riparian trees is expected to increase the length of stream
thermally suitable to brook trout and habitat availability as well as
offer a more sustainable management technique.
