Lab 4 Sampling Plant Communitiez Flashcards Preview

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Flashcards in Lab 4 Sampling Plant Communitiez Deck (18):
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For trees what are the 2 factors used to generate the importance value

1. The density of individuals ( number of individuals per unit area)

2. The size of individuals per unit area- DOMINANCE

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The IMPORTANCE VALUE

Used to estimate the ecological importance of a species in a community

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Why are these values considered relative values

Since ecologists want to know how these factors vary relative to the community as a whole

3

2 ways ecologists characterize and compare communities

Determining which species are the most important members in a community
. With respect to overall species diversity

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The simplest species diversity index is

SPECIES RICHNESS
The total number of species present in the community

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PLOT SAMPLING

Aka: QUADRAT SAMPLING
. This involves setting out rectangular plots in the forest and taking data on all individuals within the plot

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Density of individuals is determined by

counting the number of individuals within the plot and expressing this as the number of individuals per unit area ( e.g. trees per 100m^2)

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The size of a tree is determined by

measuring the diameter or cross sectional area of the tree trunk ( since trunk size correlates with overall tree size )

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BASAL AREA

this used to indicate relative tree size
. Basal area is the cross sectional area of a tree trunk and reflects the overall size of the tree

.It is calculated from measurements of trunk diameter at breast height ( d.b.h.)
. species becomes more important as its density and average size ( as expressed in basal area) increases

10

Why is soil study important

because they play an important role in determining the distribution and abundance of plants beause they affect
1. seed germination
2. competitive interactions
3. overall plant survival

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What 3 things are tested in soil

. ph
. soil moisture
. soil texture
( in respect to clay silt and sand)

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Acids

are compounds that release hydrogen ions (H+) when in a solution

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Bases

are compounds that accept hydrogen ions ( also contain hydroxide ions )

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pH

.is a measure of the negative logarithm of the hydrogen ion concentration ( ph = -log [H+}
. Is measured on a scale of 0-14

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The pH scale

Neutral = 7.0
Acidic = 7.0

Based on a logarithm scale. a change from one unit to the nest represent a a 10 fold scale

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Why do ecologist measure soil ph

.beacuse the availability of many nutrients are only available to a plant if they are in a solution
. and the tendency of a nutrient to go into a solution depends on its pH
. A soil of pH 6-7 is the ideal

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What are the 3 types of soil moisture

. Hydric ( wet) ( marshes, bogs and swamps) ( HYDROPHYTES)
. Mesic ( intermediate) ( MESOPHYTES)
. Xeric ( dry) ( rocks, grasslands, deserts) ( XEROPHYTES)

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HYDROPHYTES

Beacuse saturated soils of little oxygen for plant roots . Hydrophytes of special features that allow them to adapt, but preclude them from living in other habitats