Thesis research
Remote sensing for monitoring of wildlife habitat: Lesser Snow Geese and sub-arctic coastal marshes
Statement of Problem
Large numbers of snow geese are causing widespread destruction of the vegetation
of their breeding habitats in the Arctic. Satellite imagery can be used to assess
habitat destruction over large spatial and temporal scales and this data, along
with ground-based information, may allow management targets for sustainable
snow goose population sizes to be set.
Introduction
The number of lesser snow geese in eastern North American flyways has been increasing
rapidly, and has approximately tripled between 1969 and 1993. This has had severe
impacts on their breeding grounds, since the geese forage destructively between
the time of their arrival and the time when above-ground plant growth begins.
Because the geese depend on these same sites (coastal salt marshes) for summer
grazing, the availability of summer forage has been sharply reduced by this spring
damage. Heavy grazing on the remaining areas has reduced plant growth and reduced
forage availability still further. At La Perouse Bay, Manitoba (the site of a
breeding colony of lesser snow geese that has been studied since 1968), reduced
growth and recruitment of goslings has been detected and linked to the decline
of summer forage. Despite reduced breeding success, the population continues to
increase, largely due to increased adult survivorship. Recovery of the salt marsh
vegetation following spring damage is very slow (>15 years), particularly when
heavy goose use continues. Without intervention, the destruction can be expected
to continue.
Because the damage to breeding areas is large-scale and long-term, there are
relatively few sources of data with which to quantify it. One of these sources
is satellite data, which have been provided by Landsat since the early 1970's.
Reflectance data collected by satellite are consistent, reliably archived, and
sample large areas non-destructively. To assess the pattern and timing of vegetation
changes, the historic vegetation first needs to be mapped. Measures of vegetation
condition then need to be linked to reflectance using ground-based measurements.
These data can then be scaled up to regional levels and the regional damage
to vegetation types used by geese can be assessed using Landsat imagery.
This poster, presented at the Ecological Society of America conference in Utah,
August 2000, summarizes a good chunk of my thesis; Fig.
2 is the vegetation reconstruction. Since the poster was presented to ecologists,
some remote sensing terms are defined.
Major papers:
2002. Gadallah, F.L. Historical vegetation reconstruction of a degraded sub-arctic
coastal marsh using Landsat imagery and ancillary data. Écoscience 9:271-279.
abstract
2000. Gadallah, F.L., Csillag, F. and Smith, E.J.M. Destriping multisensor
imagery with moment matching. International Journal of Remote Sensing 21:2505-2511.
abstract link
to paper
1995a. Gadallah, F.L. and Jefferies, R.L. Comparison of the nutrient contents
of the principal forage plants utilized by lesser snow geese on summer breeding
grounds. Journal of Applied Ecology 32:263-275. abstract
(pdf) JSTOR
link
1995b. Gadallah, F.L. and Jefferies, R.L. Forage quality in brood rearing areas
of the lesser snow goose and the growth of captive goslings. Journal of Applied
Ecology 32:276-287. abstract (pdf) JSTOR
link
PDF reprints are available.