Transcript Ground Rules, exams, etc. (no “make up” exams) Text: read

Community and Ecosystem Ecology
Macrodescriptors = Aggregate Variables
Trophic structure, food webs, connectance
rates of energy fixation and flow, ecological efficiency
diversity, stability, relative importance curves
guild structure, successional stages
Communities are not designed by natural selection
for smooth and efficient function, but are
composed of many antagonists (we need to
attempt to understand them in terms of interactions
between individual organisms
Systems Ecology
Compartmentation
Trophic Levels
Autotrophs = producers
Heterotrophs = consumers & decomposers
Primary carnivores = secondary consumers
Secondary carnivores = tertiary consumers
Trophic continuum
Horizontal versus vertical interactions
Within and between trophic levels
Guild Structure
Foliage gleaning insectivorous birds
Food Webs
Subwebs, sink vs. source food webs
Connectance
Food Web
Community Matrix
Biogeochemical Cycles
Ecological Pyramids (numbers, biomass, and energy
Pyramid of energy
Measures of standing crop versus rates of flow
Energy Flow and Ecological Energetics
The energy content of a trophic level at any instant (i.e.,
its standing crop in energy) is usually represented by
capital lambda, L, with a subscript to indicate the
appropriate trophic level: L1 = primary producers,
L2 = herbivores, L3 = primary carnivores, and so on.
Similarly, the rate of flow of energy between trophic
levels is designated by lower case lambdas, lij , where
the i and j subscripts indicate the two trophic levels
involved with i representing the level receiving and j the
level losing energy. Subscripts of zero denote the world
external to the system; subscripts of 1, 2, 3, and so on,
indicate trophic level as previously stated.
Energy Flow and Ecological Energetics
Energy Flow and Ecological Energetics
At equilibrium (dLi/dt = 0 for all i), energy flow in the system
portrayed in the figure may thus be represented by a set of
simple equations (with inputs on the left and rate of outflow to
the right of the equal signs):
l10 = l01 + l02 + l03 + l04
l10 = l21 + l01 + l41
l21 = l32 + l02 + l42
l32 = l03 + l43
l41 + l42 + l43 = l04
Energy Flow and Ecological Energetics
Gross Productivity
Gross annual production (GAP)
Net productivity
Net annual production (NAP)
Respiration in tropical rainforest 75-80% of GAP
Respiration in temperate forests 50-75% of GAP
In most other communities, it is 25-50 % of GAP
Only about 5-10% of plant food is harvested by animals
Remainder of NAP is consumed by decomposers
Secondary Succession
Transition Matrix for Institute Woods in Princeton
_________________________________________________________________________
Canopy
Sapling Species (%)
Species
BTA GB SF BG SG WO OK HI TU RM BE
Total
___________________________________________________________________
_______
BT Aspen
3
5
9
6
6
2
4
2
60
3
104
Gray birch 47
12
8
2
8
0
3
17
3
837
Sassafras
3
1
10
3
6
3
10
12
37 15
68
Blackgum 1
1
3
20
9
1
7
6 10
25 17
80
Sweetgum 16
0 31
0
7
7
5 27
7
662
White Oak 6
7
4
10
7
3 14
32 17
71
Red Oak
2
11
7
6
8
8
8
33 17
266
Hickory
1
3
1
3
13
4
9
49 17
223
Tuliptree
2
4
4
11
7
9 29 34
81
Red Maple 13
10
9
2
8 19
3 13 23
489
Beech
2 1
1
1
1
8
6 80
405
__________________________________________________________________________
BTA in next generation = 0.03 BTA + 0.03 SF + 0.01 BG .
Grand Total = 3286
Distributions of Trees Observed in 4 Forests and Predicted Climax
__________________________________________________________________ __________________
Age (years) BTA
GB
SF
BG
SG
WO
OK
HI TU
RM
BE
__________________________________________________________________ __________________
25
65
150
350
Predicted
climax
0
26
-
49
6
-
2
0
0
-
0
0
2
7
45
1
6
3
18
0
5
-
0
0
0
3
3
12
22
-
0
1
0
0
0
4
0
14
20
6
70
1
1
0
2
76
4
2
4
6
6
10
63
__________________________________________________________________ __________________
Evolutionary Convergence and Ecological Equivalence