iii. Flashcards

1
Q

sapwood

A

living xylem, typically from the most-recent few years of the tree’s growth.

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2
Q

living xylem

A

transports water from the soil up to the leaves

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3
Q

the more leaves that a tree has …

A

the more sapwood it needs to get water to them

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4
Q

The xylem in
sapwood is ____ and so ____

A

living; requires energy from maintenance respiration to keep it alive

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5
Q

heartwood

A

older, dead xylem that had been sapwood when it was first created
waterproof because of being filled with secondary substances

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6
Q

when the tree turned old sapwood into heartwood

A

the sapwood had its nutrient
reserves removed, and had secondary substances added that reduce the chance of it
decaying.

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7
Q

secondary substances

A

tyloses, resins and dyes

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8
Q

tyloses

A

deformed cells that fill vessels

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9
Q

a tree does not need …

A

heartwood to be able to survive, because it is no longer functional

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10
Q

hollow trees can

A

stand up fine as long as they are in closed-forests
that protect them from high winds

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11
Q

Hollow trees growing in the open …

A

are more prone being blown down
the hollows in hollow tree-trunks concentrate the wind and that increases the chance they will be blown over

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12
Q

annual tree-rings are typically much clearer in the

A

heartwood than they are in the
sapwood

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13
Q

photosynthate

A

chemical energy created from photosynthesis

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14
Q

trees typically allocate the photosynthate in the following ranking of abundance, from
most to least

A

maintenance respiration
producing leaves and fine roots
flower and seed production
primary growth
secondary growth

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15
Q

maintenance respiration

A

the greatest amount of photosynthate is used to keep
existing tissues alive

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16
Q

respiration increases as …

A

temperature increases

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17
Q

producing leaves and fine roots …

A

to enable continued photosynthesis,
by replacing leaves that fall off seasonally

18
Q

flower and seed production …

A

to enable continued survival of a tree’s genes

19
Q

In years
when many seeds are produced …

A

trees have lower primary and secondary growth, due
to the energy put into making the seeds

20
Q

primary growth

A

elongation of terminal and lateral shoots and woody roots to enable a tree to compete with its neighbors for light and water

21
Q

secondary growth

A

new wood to conduct water

22
Q

trees growing vigorously in high quality habitat …

A

… have so much photosynthate that
maintenance respiration only takes up 25% of photosynthate, leaving 75% for growth

23
Q

trees in low quality habitat …

A

may need 75% of photosynthate for maintenance
respiration and only have 25% left for growth

24
Q

in very low quality habitats …

A

the photosynthate may go to maintenance respiration, leaving no energy to grow at all,
which results in those trees having missing rings over their whole surface

25
sudden reduction in crown size ...
can occur from people pruning leaves and branches from the tree naturally by animals browsing (e.g. spruce budworm feed on needles and buds) or wind disturbance
26
a sudden loss of >50% of the leaves typically results
in the tree dying
27
the tree will survive if it can ...
quickly “abandon” (i.e. kill) much of the now unneeded xylem tissue, by removing the nutrients from the xylem and adding resins or tyloses to them
28
how can trees survive coppicing and pollarding?
they have their upper stem portions removed during winter when the plant is dormant and has stored most of its nutrients in the trunk and roots trees must be first coppiced or pollarded when they are young and have a small diameter, and regularly coppiced or pollarded after that, to ensure that the trunk does not have a large amount of sapwood that would have a high maintenance respiration
29
tree growth efficiency
the volume of wood grown per year per area of land on which the trees are grown
30
as a tree ages ...
its functional live crown stays the same size and thus so does its gross photosynthesis but, because the total tree size is larger its respiration increases, and thus its net rate of photosynthesis decreases
31
the tree growth efficiency for trees with strong apical control is highest ...
for young trees when they are narrowly-spaced for old trees when they are more widely spaced
32
the tree growth efficiency for trees with weak apical control is highest ...
for young trees if they are narrowly-spaced for old trees when they are widely- spaced
33
stability of decurrent tree stems
will be rapidly twisted by the wind which will cause it to split in half vertically (if hollow, growing in the open, and subject to high wind)
34
stability of excurrent tree stems
if DBH is 1% of less of it's height - will have much weight concentrated over a narrow based and may, as a result of that weight, buckle, breaking horizontally several feet above the ground.
35
dense stands of trees may support each other during wind because
their roots will be entwined and their crowns will be leaning on each other
36
when trees are killed by disturbance or logging ...
the environment for the remaining trees changes due to the loss of shading of their sides: the tree’s environment will change in terms of heat, moisture, light, and wind
37
side-shade temperature increases
increased soil temperature increases nutrient availability in cold climates because the warmer temperatures increase the activity of bacteria and fungi in the soil
38
side-shade moisture
the air typically becomes drier because there are no longer so many leaves transpiring moisture into the air
39
side-shade brightness
thin shade-leaves may not be able to handle the sunlight and may thus die
40
sun-scald
may develop on a tree released from side-shade the sunlight might be strong enough to heat the dormant tree up enough to cause a part of the lateral meristem to become active; If the sunshine suddenly disappears, the temperature of the lateral meristem will suddenly drop, the tissues will freeze, and that part of the lateral meristem will die leaving a crack or a scar
41
if the tree was small when released (ages A or B)
it will grow to look like an open-growth tree, with its crown beginning low to the ground