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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
Q

usable vs. available water

A

the plant can use both pore water and available water

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26
Q

pore water is highest …

A

for sandy soils

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27
Q

unavailable water is highest …

A

for clay soils

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28
Q

available water is highest for …

A

a loam texture

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29
Q

clay holds _____ more tightly than it holds ____

A

water molecules; cations

30
Q

a loam texture has the highest ___ ___ and second highest ___

A

available water; CEC

31
Q

best soil for plant growth

A

loam texture

32
Q

nutrients

A

the chemical elements needed for plants to complete their life cycle

33
Q

macronutrients

A

are needed in large amounts as each makes up more than .1% of a plant’s dry weight

34
Q

top 9 macronutrients from largest to smallest

A

carbon, oxygen, hydrogen, nitrogen, potassium, calcium, magnesium, phosphorous, sulfur

35
Q

micronutrients

A

essential but each is less than .1% of a plant’s dry weight

36
Q

most abundant macronutrient

A

carbon
is the only macronutrient absorbed mainly by the leaves

37
Q

copper

A

can be absorbed in small amounts from rain or dust that falls on the leaf

38
Q

transport

A

nutrients absorbed by leaves travel in the phloem

39
Q

veins in a leaf

A

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
Q

most nutrients enter plants by

A

first dissolving into soil water and then entering roots

41
Q

two paths of entry

A

between cells (apoplastic) or within cells (symplastic)

42
Q

Casparian Strip

A

a waxy, water repellent layer near the outside of the roots

43
Q

where does nutrients go after entry

A

casparian strip

44
Q

relationships between amount of each plant nutrient and plant growth rates

A

deficiency range, critical range, luxury range, toxicity range

45
Q

deficiency range

A

growth changes rapidly with small changes in that nutrient

46
Q

critical range

A

small growth responses to large changes in that nutrient

47
Q

luxury range

A

plant growth doesn’t respond to changed nutrient levels

48
Q

toxicity range

A

excessive nutrients reduce growth rates

49
Q

at low abundances of a nutrient …

A

it will be taken up rapidly by the plant using selective methods at the casparian strip

50
Q

stoichiometry

A

the ratio of pairs of nutrients for plants
optimal or sub-optimal

51
Q

sub-optimal ratios

A

the plant will change its growth patterns to try an change the ratio
ex: C:N

52
Q

ratio of C:N too high

A

the plant will produce many roots to absorb N, at the expense of shoots from which it would absorb C through photosynthesis

53
Q

ratio of C:N too low

A

N is too abundant
the plants will grow few roots making it susceptible to drought

54
Q

nitrogen in plants and soils

A

plants need nitrogen to create chlorophyll, DNA, and proteins
the 4th most abundant element by weight
usually the most limiting nutrient to growth

55
Q

organic matter and inorganic compounds …

A

both contain nitrogen that can be used by plants

56
Q

atmosphere is ___ elemental N2, but …

A

78%; plants cannot biologically use it

57
Q

symbiosis

A

when 2 species live close to each other and help each other
occurs between many nitrogen-fixing bacteria and plants

58
Q

2 major forms of symbiosis between bacteria and plants

A
  • 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
Q

nitrogen deficiency

A

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
Q

phosphorous in plants

A

8th most abundant nutrients in plants by weight
2nd most likely nutrient whose limited availability is causing limitations in plant growth

61
Q

phosphorous in soils

A

usually found in forms that plants cannot use and thus accumulate in the soil (except old tropical soils)

62
Q

biological phosphorous absorption

A

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
Q

MR symbioses

A

all involve the strands of fungus extending from the soil to the root

64
Q

MR relationship with plants

A

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
Q

MR relationship with water in plants

A

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
Q

phosphorous deficiency

A

is only noticeable when very severe
leaves (esp in veins) turn purple
plants get stunted

67
Q

WWW

A

the wood-wide web reflects the connections between trees

68
Q

WWW fungus

A

connects trees of the same and different species by sharing phosphorous and water

69
Q

WWW bacteria

A

connects trees of the same and different species by sharing nitrogen

70
Q

mother trees

A

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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