i. Flashcards
Forestry
the science, art and business of managing forests to obtain goods such as
wood, water and game animals
ecology
the scientific study of relations between living organisms and their
environment
forest ecology
the scientific study of relations between forest organisms and
the forest environment
3 criteria for a forest
i. height: a forest is dominated by trees, and a tree is a woody plant that would be at least 5 meters [16 ft] in height in that location when it has become old and has reached its maximum height.
ii. area: trees cover at least 10% of the land and total at least 0.5 hectares [1.25 acres]; thus if trees cover 10% of the area there would need to be 5 hectares of land to get the 0.5 hectares of tree cover.
iii. land-use: the current primary use is not agriculture or orchard
is 0.5 hectare in area;
is nonagricultural; and will meet the height requirement as the seedlings are of a tree-species,
and trees by definition will be at least 5 meters [16 ft] tall when they are mature
open forest
if tree cover is greater than or equal to 10% and greater than or
equal to 0.5 hectares, but most of the tree crowns do not intersect
closed forest
if the crowns (comprised of the tree’s branches and leaves) of most
of the trees in an area intersect each other
characteristics of a primary forest
i. has never been extensively cleared by people,
ii. has developed following a natural disturbance (e.g. fire, wind, flooding),
iii. is dominated by natural processes as the forest grows and matures,
iv. it can have any age, from 1 year to thousands of years
secondary forest has the following characteristics
i. it developed after widespread human clearance (that is, disturbance) of the preexisting vegetation (for example, deforestation for wood or to create agricultural fields)
ii. became revegetated either artificially by the planting of trees by people, or by natural
processes such as wind or animal dispersal of tree seeds
iii. human disturbances favor different plant species than do natural disturbances
old growth forest
can be primary forest or secondary forest, are old enough that the structure of its trees and forest are distinct from the structure of trees and forest in young forests
characteristics of old growth forests
- no evidence of human disturbance, such as stumps or fences
- presence of long-lived and shade-tolerant tree species
- standing dead trees (snags)
- pit and mound shapes on the forest floor
- multiple growth layers
- many large logs in different stages of decay
- many fungus, lichens, ferns and moss, as they grow well in the shade and on rotting wood
- natural disturbances kill canopy trees and thus create canopy gaps
characteristics of old growth trees
- soaring branchless trunks
- single stems, as multiple-stems usually form from stump-sprouts that occur after a tree is cut down by people
- trunks with a diameter at breast height (DBH) of 3 ft
- “antiqued”, balding bark forms as outer bark falls off exposing different inner bark
- buttressed roots
- bizarre, sinuous growth forms
- stag-headed top
light reactions take place …
in pigments in thylakoid membranes.
dark reactions occur …
in the stroma
shade plants have lower xyz and xyz than sun plants
light-compensation point; lower light saturation
sunflecks
brief periods [minutes to hours] of sunlight that reaches the forest floor
when the sun shines through gaps in the forest canopy overhead
plants are able to predict changes in seasons by
measuring changes in daylength
phytochrome
red pigment in leaves
phytochrome mediates seasonal processes such as
seed germination, chloroplast development, and flowering
carotenoids
pigments that can be yellow, red or orange
main functions of carotenoids
to absorb some light in wavelengths not absorbed by chlorophyll, and to minimize harm to chlorophyll molecules from being exposed to too much light and they thus reduce the amount of photoinhibition that occurs.
anthocyanins
red or purple pigments
Dendrochronology
use of tree-rings to determine the timing of events in past
who discovered tree-rings
Theophrastus [Greek], around 300 BCE
who made tree-rings scientific
A.E. Douglass in 1900 CE
vascular cambium
sheath of cells that covers all the woody parts of the whole tree
each annual-ring contains a band of
earlywood and latewood
earlywood
xylem cells that form early in the growth season; the cells are large-sized
and thin-walled
latewood
xylem cells that form later in season; the cells are smaller-sized and thicker walled than the earlywood cell
the oldest-growth ring
is in the center of the tree
Annual growth rings are common in ___ areas, but are uncommon in ___ areas.
temperate; tropical
three forms of annual rings
aporous
ring-porous
diffuse porous
aporous
xylem is made of tracheids.
only in needeleaf trees
ring-porous
xylem is made of vessels
only deciduous trees have ring-porous rings
diffuse porous
xylem is made of vessels
only deciduous trees have diffuse porous rings
Principles of Dendrochronology
the principle of uniformity
principle of limiting factors
principle of aggregate tree growth
principle of regional site selection
principle of local site selection
principle of cross-dating
principle of replication
principle of uniformity
to understand how geological features are created, we should simply observe how modern processes such as erosion reshape landscapes
principle of limiting factors
although many factors influence a tree’s growth in one location, it is usually influenced most by one limiting factor.
in dry areas it is usually precipitation, in cold areas it is usually temperature, and in dense forests it is usually light
principle of aggregate tree growth
Rt = At + Ct + WDt + ODt + Et
principle of regional site selection
most species occupy a large geographic area, and thus the environmental factors that influence its growth will vary over that area
trees growing at edge of range are most likely to respond to their limiting factors
principle of local site selection
choose local sites where tree ring-widths vary greatly from year to year
principle of cross-dating
recognize that year-to-year variations in ring-widths display unique temporal patterns
try to match the unique ring-width patterns between trees, including dead trees; Frost rings, light rings, very narrow or wide rings, are useful to match between trees
identify false and missing rings that are keeping the ring-width records from different trees from matching
correct the chronology for samples that have missing or false rings, so that the correct calendar year is assigned to each ring
principle of replication
obtain many records of tree-rings from many trees because each tree will have experienced a unique history of weather, disturbances etc
if changes in ring-widths are caused by inter-annual changes in the environment, then the ring-width patterns will be apparent in many trees
if random factors cause the changes, then they will not be apparent in many trees
Field Methods
saw
increment bored cores
core which tree?
core where on tree?
coring the tree
extracting the core
coring effect on tree?
saw
sawing provides a disk (also called a “cookie”) that contains a detailed tree-ring record
if cross-dating indicates that there are missing rings, then with a disk you can search the whole disk for the location of the missing rings
disks are necessary if the tree has more than one fire scar
disks are necessary if a tree contains decaying, rotting wood
sawed disks are the preferred to obtain samples for scientific studies as disks provide the best information
increment bored cores
from the environmental perspective, the preferred method to obtain samples
3 parts of increment bored cores
the auger
the extractor/spoon
the handle
core which tree?
ease of coring: softwoods vs. hardwoods
to get oldest trees in a forest stand, core several of the tallest trees in that forest
if you want to maximize detection of local events such as within-stand disturbances, then core multiple trees that are less than one tree-height apart
if you want to minimize the signal of local events such as tree-falls, and instead maximize broader environmental signals, then core multiple trees that are more than one tree-height apart
core where on tree?
if you want to get the maximum age of the tree, core as close as possible to the ground
if you want the climatic signal from the tree-rings, avoid root flare
avoid coring into old branch holes as the core will then contain an uninterpretable mixture of branch and stem
avoid coring in cracks that go into the wood as they may be rotten, or they may simply result in no wood being extracted
DO start coring in grooves in the bark as that makes it easier for the threads of the corer to grip the tree
two types of reaction wood
tension wood in hardwoods
compression wood in needle-leaf trees
Lab Methods
wood preparation
measuring ring-widths
cross-dating
Analytic Methods
the ring-width growth
age trends
within-stand disturbance signal
outside-stand disturbance signal
climate
