Advancing Water Resources Research and Management |
BUCKET MOUNDING SITE PREPARATION FOR SUSTAINABLE
MANAGEMENT OF LAKE STATES FORESTED WETLANDS
Andrew J. Londo(1), James Schmierer1,
Glenn D. Mroz2, David Reed2,
and Margaret R. Gale3.
INTRODUCTION
In order to sustainably manage northern forested wetlands, a
balance must be drawn between the need for fast regeneration of
overstory species while maintaining the ecological process and
function of the wetland. The occurrence of raised microsites is
critical to both natural and artificial regeneration in wetland
areas. Current harvesting equipment and methods level suitable
regeneration microsites and eliminate large trees, the source of
the natural pit and mound microtopography. Consequently, site
preparation that creates raised microsites following harvesting is
needed.
Bucket mounding is the inversion of soil onto the forest floor,
creating raised microsites for planting. However it's use in
wetlands is controversial since it is not recognized as a standard
practice. This research was initiated to examine the effects of
bucket mounding site preparation on select processes of northern
forested wetlands.
MATERIALS AND METHODS
Study Site
The study site is in the watershed of the West Branch of the
Sturgeon River in Alger County Mi. It is composed of two
plantations bucket mounded in 1988 and 1991 planted to jack pine
(Pinus banksiana) and tamarack(Larix laricina) and an uncut
control. The control stand is dominated by mixed northern
hardwoods and natural pit and mound microtopography. In all stands,
three, 30m2 plots were established.
Soil Carbon
Samples for total soil organic carbon determination were collected
from each plot. Samples were stratified by microtopographic
feature (pit, mound, and flat), as well as sampling depth (forest
floor, 0-5cm, 6-10 cm, and 11-15 cm.). Samples were pooled by
feature and depth, with carbon content determined on a Fissions
Instruments NA 1500 C/N Analyzer.
Microtopographic Mapping
Elevations from a central reference point were generated for pits,
mounds, and flat areas for each of the established study plots
using a standard surveyors level. For each feature measured, XYZ
coordinates were collected in order to determine relative heights,
and depths of the features.
RESULTS AND DISCUSSION
Soil Carbon
The soil carbon content of the stands was different with the
control and 1988 plantation being similar, followed by the 1991
plantation. Soil depth was significant with the 0-5 cm depth
exhibiting the greatest values. There were no differences between
features.
This data indicates that within seven years following harvesting
and site preparation, these sites are once again accumulating
carbon. Carbon accumulation is a key wetland function. While more
long term results are needed, this carbon recovery could indicate
that mounding is a sustainable practice, in terms of wetland
function.
Microtopographic Mapping
Results from the microtopographic mapping show that there are
differences in the distribution of size of features between the
three stands. Overall, there are deeper pits and taller mounds in
the plantations versus the control. In addition, there are twice as
many features in the control as in the plantations. While this may
not be significant in terms of plantation productivity, it may
affect native floral and faunal recovery on these sites.
CONCLUSIONS
Our preliminary results presented here are very encouraging.
The microtopography data indicates that bucket mounding not only
creates deeper pits and higher mounds, but also fewer overall
features than what is found naturally. This could have impacts on
native faunal recovery on the site. The carbon content data
indicates that these sites are able to recover relatively quickly
following mounding. Soil organic carbon/organic matter plays a key
role in soil nutrient status and sustainability, as well as wetland
process and function. Our data indicates that these sites are
accumulating carbon after only seven years following site
preparation. This can have significant impacts on long term
productivity and sustainability of these sites.
ONGOING WORK
Ongoing work on the bucket mounding project includes detailed
microtopographic mapping of newly bucket mounded sites. These
sites have two different sized mounds on them, single and double
scoop mounds. Microclimatic and hydrological studies are being
conducted, along with survival and productivity of these newly
established, and existing plantations.
ACKNOWLEDGMENTS
We would like to thank the State of Michigan Research
Excellence Fund, USDA Competitive Grants Program, and Mead
Publishing Paper Division of Escanaba Michigan for their support of
this research.
1. Graduate students, 2 professors, and 3associate professor,
School of Forestry and Wood Products, Michigan Technological
University, Houghton Mi. USA.
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Copyright © 1999 American Water Resources Association
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