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Forest Ecology > ii > Flashcards

ii Flashcards

1
Q

biota

A

all the living organisms in an area

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2
Q

types of biota

A

plants, animals, bacteria, fungus, etc.

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3
Q

bacteria

A

single-celled organisms
can be photosynthetic or not photosynthetic

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4
Q

non-photosynthetic bacteria

A

some feed on dead organic matter, and some feed on living organisms

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5
Q

fungi

A

are single-celled or multi-celled
none are photosynthetic
some feed on living organisms and on dead organic matter

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6
Q

many species of soil biota …

A

are decomposers

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7
Q

how much biota is in 1 m^2 [39 in x 39 in] of soil in a forest?

A

200000 inverterbrate animals [e.g. insects and worms] from 200 species

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8
Q

1 gram [1/28] of soil has how many species of what?

A

1 million different species of bacteria

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9
Q

soil texture

A

consists of mineral particles less than 2 mm [1/12 “] in diameter

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10
Q

larger particles such as stones …

A

are “in” the soil, but are not “the” soil itself just like living organisms, dead organic matter, and water

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11
Q

mineral particles from largest to smallest

A

sand (.05 - 2 mm) -> silt (.002 - .05 mm) -> clay (<.002 mm)

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12
Q

loam

A

consists of equal amounts of all three textures (40% sand, 40% sand, 20% clay)

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13
Q

the ____ the texture of the soil, the ____ it’s surface area

A

finer; greater

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14
Q

cation exchange capacity

A

the amount of cations that can be absorbed and released by a standard weight of soil

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15
Q

H+ Abundance

A

H20 + CO2 -> H2CO3 -> HCO3 + H+

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16
Q

relationship between cations and hydrogen ions

A

cations are released from the soil when hydrogen ions are present in the soil. since hydrogen ions are active, they push the cations off the soil

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17
Q

CEC increases as

A

the soil texture becomes finer

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18
Q

CEC is highest for

A

organic soils because they have humus particles

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19
Q

humus particles

A

tiny clay-sized particles of broken down organic matter which also have negative charges on their surface, so they absorb and release cations

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20
Q

soil water types

A

pore water, unavailable water, available water

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21
Q

pore water

A

fills pores between mineral grains but drains away due to gravity within a few days

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22
Q

unavailable water

A

water that adheres directly to the soil particles - so strongly that it can’t be removed by a plant

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23
Q

available water

A

water that coheres to unavailable water, and is held loosely enough that plants can remove it and use it

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24
Q

when is available water most abundant

A

right after rain, but progressively smaller amounts available for up to 2 weeks

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25
usable vs. available water
the plant can use both pore water and available water
26
pore water is highest ...
for sandy soils
27
unavailable water is highest ...
for clay soils
28
available water is highest for ...
a loam texture
29
clay holds _____ more tightly than it holds ____
water molecules; cations
30
a loam texture has the highest ___ ___ and second highest ___
available water; CEC
31
best soil for plant growth
loam texture
32
nutrients
the chemical elements needed for plants to complete their life cycle
33
macronutrients
are needed in large amounts as each makes up more than .1% of a plant's dry weight
34
top 9 macronutrients from largest to smallest
carbon, oxygen, hydrogen, nitrogen, potassium, calcium, magnesium, phosphorous, sulfur
35
micronutrients
essential but each is less than .1% of a plant's dry weight
36
most abundant macronutrient
carbon is the only macronutrient absorbed mainly by the leaves
37
copper
can be absorbed in small amounts from rain or dust that falls on the leaf
38
transport
nutrients absorbed by leaves travel in the phloem
39
veins in a leaf
contain xylem and phloem xylem conducts water from the branch out to the edge of the leaf phloem conducts carbohydrates from the leaf towards the branch
40
most nutrients enter plants by
first dissolving into soil water and then entering roots
41
two paths of entry
between cells (apoplastic) or within cells (symplastic)
42
Casparian Strip
a waxy, water repellent layer near the outside of the roots
43
where does nutrients go after entry
casparian strip
44
relationships between amount of each plant nutrient and plant growth rates
deficiency range, critical range, luxury range, toxicity range
45
deficiency range
growth changes rapidly with small changes in that nutrient
46
critical range
small growth responses to large changes in that nutrient
47
luxury range
plant growth doesn't respond to changed nutrient levels
48
toxicity range
excessive nutrients reduce growth rates
49
at low abundances of a nutrient ...
it will be taken up rapidly by the plant using selective methods at the casparian strip
50
stoichiometry
the ratio of pairs of nutrients for plants optimal or sub-optimal
51
sub-optimal ratios
the plant will change its growth patterns to try an change the ratio ex: C:N
52
ratio of C:N too high
the plant will produce many roots to absorb N, at the expense of shoots from which it would absorb C through photosynthesis
53
ratio of C:N too low
N is too abundant the plants will grow few roots making it susceptible to drought
54
nitrogen in plants and soils
plants need nitrogen to create chlorophyll, DNA, and proteins the 4th most abundant element by weight usually the most limiting nutrient to growth
55
organic matter and inorganic compounds ...
both contain nitrogen that can be used by plants
56
atmosphere is ___ elemental N2, but ...
78%; plants cannot biologically use it
57
symbiosis
when 2 species live close to each other and help each other occurs between many nitrogen-fixing bacteria and plants
58
2 major forms of symbiosis between bacteria and plants
- bacteria in root nodules on plants, especially legumes and alder trees - free-living bacteria can form loose associations with plants whose roots leak nutrients
59
nitrogen deficiency
leaves turn pale green and then yellow due to chlorosis (chlorophyll death), because they do not have enough Nitrogen to make the chlorophyll stunts plants
60
phosphorous in plants
8th most abundant nutrients in plants by weight 2nd most likely nutrient whose limited availability is causing limitations in plant growth
61
phosphorous in soils
usually found in forms that plants cannot use and thus accumulate in the soil (except old tropical soils)
62
biological phosphorous absorption
mycorrhizae are fungi that are symbiotic with plant roots. all coniferous plants and 80% of flowering plants have a symbiotic relationship with a species of MR
63
MR symbioses
all involve the strands of fungus extending from the soil to the root
64
MR relationship with plants
provide many nutrients to the plant root, especially important for phosphorous excrete an enzyme that releases phosphorous from strong chemical bonds in the soils and then into the plant
65
MR relationship with water in plants
MR strands can grow 4 in. in one day (roots only 1 in/day) MR provides water to plants, especially during droughts, speeding up plant recovery
66
phosphorous deficiency
is only noticeable when very severe leaves (esp in veins) turn purple plants get stunted
67
WWW
the wood-wide web reflects the connections between trees
68
WWW fungus
connects trees of the same and different species by sharing phosphorous and water
69
WWW bacteria
connects trees of the same and different species by sharing nitrogen
70
mother trees
old trees that have been in the forest for a long time and thus have many fungal and bacterial connections connect many living trees helps new trees become established by having fungal and bacterial partners that then reach and help the new tree establish

Forest Ecology (3 decks)

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