Environmental Biology
BIO 212
Karl Kleiner
LAB 1
AN INTRODUCTION TO PATTERNS IN NATURE
There are two goals to this lab. The first is to sharpen your powers of observation.
The second objective is to familiarize you with tree identification. Our first exercise will work on
both of these skills. Trees are a large feature of the landscape, and knowing them is a good way to
start becoming familiar with your natural surroundings. The number and diversity of tree species
present, and their size and spacing, can provide many clues to the type of climate, soils and past
land use patterns of the area.
We have for our use, a little book titled, “Tree Finder.” This is a simple, dichotomous key
that primarily uses leaf shape for keying out tree species. Although it isn’t exhaustive, it is fairly
quick and easy to use. Using an identification key requires you to slow down and use your sense of
sight, touch, smell and sometimes taste! One thing you can’t do is jump to conclusions. You want to
be clear about what each statement in the key is asking, and you want to be sure that you have
adequately addressed it.
Our second exercise will build upon your skills of observation and add another component –
asking questions. Recall from lecture, that scientific studies generally progress from description of
pattern, to hypotheses to explain those patterns. Eventually, these hypotheses are coalesced into
theory that seeks general explanations for many patterns in nature. This lab will introduce you to
two of the crucial elements of the scientific process; (1) recognizing patterns in nature and (2)
documenting or testing those patterns.
We began with an observation and then asked questions about what we observed. To test
whether these questions might be true, we turned them into statements called hypotheses. In your
first lab, you will make an observation about the distribution of a plant between two areas of lawn at
Reservoir Park. You will then ask yourself questions about the pattern you observe and form a
hypothesis. Remember that it is always best to start any investigation by asking the most inclusive
(general) question. We will then conduct a sampling to test a hypothesis that the class has agreed
upon. This exercise should 1) help focus your process of inquiry and 2) provide an understanding of
how ecologists gain an understanding of natural patterns.
Except for extremes, humans are not very good at discriminating among small differences in
the environment or detecting gradients of factors (light, water, or minerals) that directly affect other
organisms, like plants. During your second lab, you will analyze your results so that you can
understand how ecologists interpret their data, and thus the pattern they originally observed.
Rev. 9/10
Environmental Biology
BIO 212
Karl Kleiner
2
Today’s Activities - Sampling in the environment
Your exercise will be to:
1) Make some observations,
2) Form a hypothesis based on your observations
3) Conduct a sampling to collect data to test your hypothesis.
We will visit a small patch of lawn near the Jackson street commuter parking lot. I will ask you to
observe the distribution of a common lawn forb, the common blue violet (Viola sororia). (A forb is
an herb other than grass. Why don’t I refer to them as weeds?) Specifically, we are interested in the
distribution of the common violet. So, for starters, take a walk around the area that I indicate and
make some observations about the density and distribution of the common violet.
♦ What observations can you make about the distribution of this species?
♦ What questions do you have about the distribution of this species?
♦ Now, form a hypothesis about the general distribution of this species.(Where is it growing?)
A. Sampling layout for vegetation patterns.
During lab we will discuss how to sample the area for V. sororia in an unbiased manner. Once we
have settled on a sampling method, you will count the number of violet leaves in a small, circular
quadrat. (I’ll explain the how and why during lab). Record these on the data sheet. I will collect the
data sheets at the end of lab.
Based on your data, what hypothesis would you propose to explain the distribution of
plants? Can you think of any environmental variables that you would want to measure to help
support your hypothesis?
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Environmental Biology
BIO 212
Karl Kleiner
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Asking questions about patterns in nature
You can very quickly begin to sharpen your powers of observation in the field if you carry
with you, in a lightweight mental knapsack, a series of questions about the patterns, rhythms and
contrasts that exist in any habitat, with regard to both the habitat itself and the organisms that live
there. The following is a sampling of such questions, or of observations that generate questions.
Some will interest you more than others; if you begin by asking these of yourself more or less selfconsciously when you go out into the field, the questions will soon become more or less automatic
and subconscious, and you will find much to intrigue you in almost any outdoor situation.
Patterns in space-- Are individuals species, or groups of species:
1a) Distributed in clumps? b) Scattered more or less at random? c) Spaced out, as
individuals, more or less evenly? If clumped, how densely? If spaced out, how far apart
are the individuals?
2) What might these spatial patterns be related to? Topography? Soil differences? Patterns of
shade or sunlight? Some past disturbance? Human land use patterns? The species mode of
dispersal? Competition with other members of the species, or with other species?
3) Do some species seem to characteristically occur together?
4) Do "island communities" differ in composition from larger, more continuous communities?
Patterns relating to time:
Many different stages of ecological succession (recovery of vegetation after disturbance) are
often present in a landscape, the stage being defined by the length of time elapsed since the last
disturbance. Do these different successional stages possess clear-cut contrasts in the types of plants
and animals that are present? Do the plants and animals characterizing one stage differ in such
things as growth rate, reproductive rate, dispersal mode, food types eaten, etc. from those of another
stage?
Within the same stage of succession are there contrasts related to:
1) Local habitat differences?
2) Different types of initial disturbance?
3) The seasonal timing of initial disturbance?
What contrasts exist among communities subjected to repeated disturbance, but at different
intervals--e.g. fields mown frequently and fields mown more rarely?
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Environmental Biology
BIO 212
Karl Kleiner
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What about phenological contrasts-- contrasts in the seasonal activity stages of different
species, related not to past disturbance but simply to the rhythm of the seasons? Does the
occurrence of plant species change from Spring through Summer?
Reproductive and dispersal adaptations:
1) Do particular plant types seem to have particular pollinators?
2) If so, are their flowers adapted to these particular pollination species?
3) How specific are the pollinators for particular plants?
4) Do pollinators follow a sequence of different plant species through a season?
For a given plant species:
1) What are the main means of dispersal of its seeds.
2) How many seeds does it produce, and is this related to seed size, mode of dispersal, or
distance of dispersal?
3) Are these parameters correlated with the normal habitat and/or the successional status
of the plant species?
4) What kinds of predators make use of its seeds? Does the plant have a "reproductive
strategy" that includes adaptation to the predator in terms of periodicity, difficulties in
opening the seed, unreliability of reward, etc.?
5) What is the relative importance of vegetative vs. seed reproduction for different plant
species?
Mode of survival during unfavorable periods or places
Unfavorable periods may mean climatic extremes such as drought or severe winters--or for
successional species, it may mean times when a habitat is unsuitable because it is at the wrong stage
of succession. Is the fitness (reproductive effort) of an organism altered from one location to the
next? Does a particular plant species exhibit extensive herbivore damage in some locations or at
some times compared to others? You can think of other situations. Ask yourself how the species
survives such hardships.
Microclimatic contrasts and their biological expression:
Any landscape has lows, highs, areas that are wetter or drier, cooler or warmer, more or less
exposed to sun or wind. Very localized meteorological measurements often are of great interest
because they reveal such a surprising range of conditions in what may be a small and superficially
quite homogeneous area. Often these physical contrasts may be correlated to biological patterns that
otherwise might be quite mysterious.
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Environmental Biology
BIO 212
Karl Kleiner
Your Names _____________________________
DATA SHEET
For Distribution of Viola sororia
X,Y Coordinates
Number of leaves
__________
_________
________
_________
________
_________
________
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