GEOG2800 Geographical Tutorial and Field Work
Alps Field Class
2004
School of Geography
University of Leeds
Dr Steve Carver
Life on the edge: vegetation succession in newly
deglaciated environments
Background
"The ecosystem is the basic fundamental unit in ecology, because it includes both
organisms... and abiotic environments, each influencing the properties of the other
and both necessary for the maintenance of life." (Odum, 1954)
The Alpine setting provides opportunities to experience a tremendous range of
environments. Because of the steep gradient in physical conditions, we can, by
moving up or down 1000m in altitude, effectively travel between biomes normally
spanning more than 1000km of north-south distance (i.e. coniferous boreal forests to
Arctic tundra). This makes the ecology of mountain areas both interesting and
important geographically as the habitats represented are extremely sensitive to
environmental change.
While ecosystems can often be classified in broad terms as a result of the prevailing
regional climate, in reality they vary greatly in space. For example, differences in
insolation between adjacent north-facing and south-facing hill-slopes profoundly
affect the nature of Alpine vegetation. Ecosystems also change through time. For
example, the advance and retreat of Alpine glaciers creates special challenges for
plants and animals. Advancing glaciers scrape all soil and life away, while retreating
glaciers leave behind an unpromising mix of coarse and fine-scale debris, migrating
stream channels, and a highly frost-prone environment. Even when not undergoing
primary succession from a standing start (like plants colonising the pro-glacial desert),
ecosystems may be constantly changing. Change is usually “exogenous” (i.e. forced
from the outside, and can have natural or human causes) such as the earlier flowering
of plants and breeding of birds in the northern hemisphere in response to recent
climate warming.
The pre-fieldwork exercise should have helped familiarise you with these two core
themes in ecology in an Alpine context; namely, the way in which vegetation is
controlled by the physical environment (such as temperature and soil); and how
vegetation responds to environmental changes, natural or man-made.
Succession and disturbance:
The process of plant colonisation and community development is known as
succession. This is a fundamental concept in ecology that states that there is a
definable sequence of successional stages through which an ecosystem will pass.
Primary succession by definition starts with a bare substrate and a pioneer
community, whereas secondary succession occurs after an existing successional stage
is disturbed (e.g. by fire). During succession, a change of the species structure and
organisation of an ecological community is observed over time wherein some species
may become less abundant (or disappear entirely) while others may become more
abundant or enter the community from adjacent ecosystems. Ecological succession
ends with a stage called climax. This final stage occurs when the vegetation reaches
equilibrium with the local environment. Some environments never reach climax
because processes of disturbance interrupt the natural succession.
Succession and associated processes of disturbance and interruption have has always
been important parts of nature at the local scale, but successional processes become
especially important at critical points in the earth’s history. One such time was
around 10,000 years ago when the Earth emerged from the latest glacial period.
Another is occurring now, as ecosystems are disrupted by people on an unprecedented
scale, with the result that much of the world’s vegetation is massively altered and
changing in response.
Fieldwork
The development of life in the wake of the receding Alpine glaciers provides an
excellent small-scale model for the massive primary succession events that happened
across the Northern hemisphere in the Quaternary period during the transitions
between glacial and inter-glacial phases. Studying the processes of succession in the
Alps therefore provides us with a window on the distant past. It also provides a
window onto a possible near-term future, if the Greenland and Antarctic icecaps melt
significantly and reveal large new land surfaces.
In the field, we will explore four key questions about the successional process:
 Which species appear first?
 How fast is the overall process of vegetation development?
 What factors determine whether or not species colonise?
 What factors determine the spatial patterns of colonisation?
Aim:
To map the spatial and temporal patterns in vegetation succession within the forefield
and valley of the Ödenwinkelkees glacier.
Objectives:
1. identify the plants and record the vegetation structure along transects of your
choice (e.g. down valley from the glacier snout, along valley cross sections, across
key geomorphological features or on the river braidplain);
2. develop an understanding of how life establishes itself in newly deglaciated and
active alpine/pro-glacial environments; and
3. attempt to determine the relative effects of key factors controlling spatial and
temporal patterns of colonisation.
Methods:
Pre-fieldwork planning: Carefully study maps and aerial photographs prior to
fieldwork and (a) generate some simple hypotheses on how key environmental
processes (e.g. glacier retreat, insolation, altitude, etc.) are likely to affect vegetation
patterns, and (b) identify transects along which you might collect plant survey data in
support of these. A different transect should be surveyed each day in support of
different hypotheses (e.g. a long valley transect to investigate vegetation succession in
the face of glacial retreat and a cross-valley section to investigate
altitudinal/insolation effects). Think about what data you should collect at each
quadrat with a view to what is measurable, the time available to you in the field and
how you might analyse it later using graphical and/or statistical methods. In
developing your hypotheses you might like to think about some of the following
questions.
 What types of plants might you expect to find and where?
 What are the key environmental processes affecting rates of succession?
 How does topography and geomorphology affect vegetation patterns?
 What are the principal disturbance processes and how might these affect
succession?
Fieldwork: Once in the field, identify your transect end points and adjust these if
necessary to suit local conditions such as safety and access. Walk your transect from
end point to end point and carry out quadrat surveys of plants at intervals along the
transect. Choose a suitable interval for uniform conditions (e.g. 50 or 100m) and
record a quadrat at key points (e.g. at dated moraines, at the trim line, on different
substrates, etc.). Within each quadrat record key ecological variables such as species
diversity, frequency, plant density and height. At each quadrat it is also important to
carefully record additional information such as geographic coordinates (using GPS),
altitude, slope, aspect, substrate, soils depth and soil moisture. It might be a good idea
to develop your own systematic record sheet in your notebooks to assist in this
process. Vegetation samples can be collected, bagged and labelled for later
identification. Equipment available to you includes:
 1x1m quadrats
 compass clinometers
 3 and 30m tapes
 plastic sample bags
 hand-held GPS units
 laminated maps and aerial photographs
 laminated flower/plant guide
 digital camera
Post-fieldwork analysis: Once back in the classroom you should:
1. identify any plants that could not be recognised in the field;
2. organise your data (e.g. categorise plants into species or other groupings such as
pioneer or climax, create GIS data layers, enter data into spreadsheet, etc.);
3. create appropriate graphs and maps and perform exploratory statistics;
4. develop model(s) to test your hypotheses (e.g. correlation, regression, t-tests, etc.);
and
5. make presentation of results, analyses and conclusions.
Helpful web links:
http://forest.wisc.edu/facstaff/radeloff/ No10_vegetation_biodiversity.pdf
http://www.geog.ubc.ca/courses/geog516/talks_2000/classifyingvegetation.htm
http://www.physicalgeography.net/fundamentals/9i.html
http://www.jncc.gov.uk/Publications/alpine_biodiversity/ALPNET_BOOKLET_small.pdf
http://www.pph.univie.ac.at/igbp/igbp_highres.html