BIOL 3447- Midterm Flashcards
forestry
the science, business, art, and practice of purposefully organizing and using forests and their resources to benefit people
silviculture (4)
- translation of knowledge into methods for managing stands to meet objectives
- ensures long term stability, vitality, and resilience
- aims to maintain diversity, increase productivity, and emulate natural patterns
- primary functions are: control (establish composition, structure, growth), facilitate (e.g. thinning), protect, salvage
realm of silviculture
- broad and interdisciplinary (biological, physical, social, humanities)
- Possibilities constrained by biological and physical
- Actions impacted by admin and economics
- Management impacted by law, policy, and democracy
scale of silviculture
forest (area dominated by trees, no ownership) -> forest estate (area managed for resources or other benefits, ownership) -> stand
stand
- a group of trees that
- grow together at a particular time and place
- can be managed as a unit
- have a unique set of characteristics
- can be maintained through treatments
technology of silviculture
treatments (e.g. tending, harvesting, etc.), intensity (intensive vs extensive), sequence
intensive
high operating cost and investment, maximizes timber production
extensive
low operating cost and investment, broad swath of land
high grading
only harvesting commercially valuable trees (large, high quality saw logs)- cull, poor quality trees are retained
diameter limit cutting
only harvesting trees above a certain DBH
sustained yield management
- balance of harvesting, regrowth, and regeneration (only harvesting the quantity of trees that can be regenerated)
- some timber income is reinvested
- supports the ecosystem, but you’re still focused on timber production
ecosystem based management (4)
- emphasizes multivalued
- recognizes hierarchy (can’t manage one thing without managing the whole thing)
- broad spatial and temporal scales
- detailed monitoring, adaptive management, and holistic approach
ecosystem based management in forestry
- maintain a complex ecosystem
- attend to stand structure and function over broad spatial and temporal scales
- supports:
- economic and ecological vitality
- transformation of landscapes
- creation and maintenance of ideal conditions
- multiple values
describe forest stands after fire
fire adapted trees remain, understory and overstory mortality, seeds dropped are likely to grow
describe forest stands after historic logging
conifers targeted for removal, balsam fir and white birch retained, more mixed wood stands, lower quality stems, less profit and job, increase in insect and disease damage
describe the homogenization of landscapes
all the forests in NA were cut and abandoned at the same time, so they all grew and matured at the same time
landscape equilibrium
- through time forests shift from young to mature to old, the areas may shift but the general ratio remains the same
- fire suppression has changed this ratio
- trying to maintain natural ratio during silviculture
values of forests
provisioning (goods), regulating (carbon sequestration), supporting (oxygen production), offering (cultural, spiritual)
functional zoning approach
- looks at the forest as a series of zones: ecosystem management, full protection, intensive management, fibre farms
- characteristics: science based, ecologically driven, adaptive
- goals: maintain biodiversity, increase productivity, meet wood supply demands
ecosystem management
- 74%
- reduced timber production, longer rotation periods, diversification of cuts, preservation of biological heritage
full protection
- 12%
- includes all ecosystem types, controls required
intensive management
- 10%
- traditional silvicultural, indigenous species, allows more land to be put into full protection, typically the best sites
fiber farms
- 4%
- hybrid larches and poplars
silvics
the biological characteristics of trees and the communities they form
parcelization
dealing with sections of land with different owners and different goals, makes land management difficult
fragmentation
forest is broken up into smaller isolated patches
inherent edge
- naturally arise due to environmental factors
- e.g. topography, fire, flooding
induced edge
- caused by human disturbance
- e.g. logging, urbanization
ecological trap
- environmental cues that were once reliable indicators for habitat selection become misleading and encourage organisms to make poor choices
- Indigo buntings are attracted to inherent edges, but are often attracted to induced edges (higher predation) because they can’t tell the difference
describe Ontario’s landscape diversity
3 main ecoregions, 20 ecozones, 3 forest regions and management zones, 3 watersheds (Hudson bay (moves N and drains into the arctic ocean), GLSL (moves S and drains into SL), Nelson River (moves W and drains into HB))
organization of Ontario’s forests
area of the undertaking (where forest management occurs in ON) -> forest management unit (area identified for forest management and planning) - sustainable forest licence (company or group of companies responsible for management, planning, road building, monitoring, reporting, etc.)
GLSL
- GB: mixed wood, podzols and brunisols, snow belt and high precipitation, hilly topography, thin glacial till, lacustrine silt and sand
- Sudbury NB: trembling aspen and white birch, extensive disturbance, podzols, water modified till, lacustrine silt and sand
- Nipissing Forest: >1 000 000 Ha, predominant age class is 60-100, 8 protected old growth areas
- NB is at the bottom of a fault valley, parent material was made available 10 000 yrs of ago (recently)
- Nipissing Forest: >1 000 000 Ha, predominant age class is 60-100, 8 protected old growth areas
- Algonquin Pontiac: black spruce, sugar maple, and white pine, shield topography
growing degree day
- GDD= (Tmax + Tmin) / 2 – Tbase
- used to determine if a climate is warm enough to support species with temperature dependent growth curves
- accumulate when the avg temp is above a specific threshold temperature
key drivers of regen (5)
climate, soils, topography, threats, and timing, quality, and maturation of seed production
climate
WP: 500-2000 mm precip, July temps 18-23, GS of 90-180 days
H: >700 mm precip, July temp of 17, GS >80 days
RO: 500-1500 mm precip, avg annual temp of 4, 1333 GDD
SM: >500 mm precip, avg annual temp of 2, GS>30 days
Description
WP: Long lived, genetically diverse, rapidly growing, high economic and ecological value
H: Large, long lived, slow growing, can live in suppression for hundreds of years
RO: 20-25 m and 30-90 DBH, can grow up to 30 m and 120 DBH
SM: Predominant late successional species
site conditions
WP: sand or sandy loam
H: mesic zones
RO: deep, porous, gravelly soils
SM: rich well drained soil
RM
WP: 15, best production at 50, seed crops every 3-5 and bumper crops every 10-12
H: 40, seed crops are frequent and consecutive, no seed bank
RO: 20-30, best production at 50-75, production drops off at 250, good crops every 2-10 yrs, some failure yrs
SM: Best production at 40-60, good seed crops every 2-5 yrs, produce some seed most yrs
Increased by
WP: warmth, size
H: warmth, shade, moisture
RO/SM: size
threats
WP: prolonged rain, predation
H: drought, thick OM
RO: insects, predation
SM: thick OM
Germination
WP: 60 day CS, soil surface temps 20-30
H: Low GR, 60-90 CS, optimal surface temp 15
RO: GR depends on spring conditions, CS, Viability decreases after the first yr
SM: Low GR, CS, Germinates at low temp
shade tolerance
WP: mid, GB in full sun
H: tolerant, requires canopy to develop, GB in 55% sun
RO: mid
SM: tolerant
response to release
WP: quick if less than 30, best response if LCR is 33%
H: increases with size and age
RO: good from mod suppression
SM: suppressed trees can bolt fast
7 key concepts in disturbance ecology
intensity, severity, size, frequency, residuals, rotation period, return interval
intensity
measure of physical energy released by the disturbance (e.g. 800C fire)
severity
measure of the impact of the disturbance (%mortality)
size
foot print of the disturbance
residuals
organisms/propagules that survive the disturbance
frequency
how often do disturbances like this occur
rotation period
how long would it take for an area of a particular size to be exposed to a particular event
return interval
avg time between disturbances of a given magnitude/severity
succession
direction change of species composition/strucutre over tie
primary succession
- occurs in areas that have not supported vegetation previously
- retains no residual structure from previous ecosystem
secondary succession
- occurs in areas that have supported vegetation previously
- residual structures from previous ecosystem (e.g. seed bank, individuals, propagules)
coastal sand dunes
Thousands of yrs ago, ice sheets were advancing and eventually retreating; as they retreated, the land that was depressed underneath began to rise and continues to rise today, causing lake levels to decrease (isostatic rebound) and exposing fresh sand
components of coastal sand dunes
- beach: most recently exposed
- dune I: protects the slack, colonized by beach grass that builds the dune
- slack: protected from wind by dune I, hot and dry, drought tolerant plants
- Dune II: used to be dune I, larger and older, support more vegetation
- Savannah: used to be the slack, dry sandy soil, grass/prairie/savanna ecosystem, doesn’t typically progress past this stage due to poor soil
Lake Michigan sand dunes
- Most changes occur in the first 500 yrs
- Percent cover of vegetation increased (grass and shrubs ->conifers -> hardwoods)
- Soil development
- O horizons formed, A horizon got thicker, B horizon got deeper
- Bulk density decreased
- Soil moisture increased
american beach grass
growth is stimulated by burial, rigid underground stems break apart and create plantlets which easily disperse in water allowing them to colonize beaches, creates surface roughness to accumulate sand
glacier bay
- Glacial recession over 200 yrs to expose glacial till
- 4 stages:
- Colonizing crusts of blue green algae fix nitrogen
- 35-45 yrs- dryas community
- 60-70 yrs- alders fix nitrogen
- 200+- spruce climax
Piedmont old fields
- Crab grass colonizes immediately after the field is abandoned (fall of yr 0)
- Horseweed colonizes the following year (yr 1)
- seeds mature early- germinate in the first fall, overwinter as rosettes (basal leaves), bolt in the spring growing a stem and producing seeds
- allelopathic- eliminates itself after one year (its seeds don’t germinate and survive in environments where horseweed has already lived), dramatically reduced in the second year
- Asters colonize after the horseweed (yr 2)
- Composite flowers (ray and disc florets), mature late, seeds don’t germinate until the following spring (able to colonize after the horseweed has eliminated itself)
- Broom sedge (yr 3)
- Spring germination, require cold stratification, drought tolerant (able to outcompete the aster for water)
- Shortleaf pine (yrs 5-15)
- Seeds are dispersed by wind (travel further and faster than other transportation methods), grow rapidly (significant early growth), competes for water
- requires bare mineral soil (unable to establish in areas with litter) and establishes in patches
- establishes the beginning of a canopy, creating shade, and causing its own elimination
- mid-tolerant and tolerant species- oaks, hickories (yrs 50-150)
- larger seeds take them longer to get there but allow them to penetrate the litter layer
faciliation
species can have positive effects that facilitate the presence of others (species A effects the environment such that species B is facilitated), climax species has a positive influence on its own perpetuation on that site
inhibition
certain species can have negative effects on the presence of others and themselves (species A inhibits species B from colonizing the site allowing species A to hold the site for longer), includes species that are allelopathic (e.g. horseweed), depends on who gets there first
tolerance
no net effects of one species on another, succession depends on which species gets there first (whichever species has the most efficient mechanism of dispersal), species have to arrive at a time in which the microenvironment is suitable (e.g. even if the shortleaf pine reaches the site, if there is no bare mineral soil exposed, they won’t be able to colonize the site)
random colonization model
no structure, you can’t predict from one event to another- no interactions that are influencing the trajectory of colonization, uncommon
species change
- dependent on:
- environment (favourable vs sever)
- succession (early, mid, late)
stages of stand development
- Stand Initiation: species arrive over a period of several years as a result of movement of seed
- Stem Exclusion: superior individuals are outcompeting inferior individuals, no new colonization
- Understory initiation: advance regeneration
- Old growth: characterized by a particular age, structure, or environmental driver, gap phase dynamics, may not be reached in silviculture
crown position and stratification
dominance is determined by light availability and stratification is determined by height above the forest floor
single cohort stand
trees establish after a single event, more severe and less frequent disturbances, manage the whole stand
multicohort stand
trees establish after 2 or more events, less severe and more frequent disturbances, manage individual trees, reverse J curve
forest regeneration objectives
manage the environment, enhance tree response, ensure survival
afforestation
no original source of seeds/sprouts, minimal influx of propagules, requires artificial stock
reforestation
potential for natural seed/sprouts, choice of natural, artificial, or combined stock
size demographics
distribution is a reverse j curve due to environmental variability and asymmetric competition- dominance heirarchy
density demographics
due to size hierarchies, biomass is a better measure of carrying capacity
law of constant yield
initially yield and density increase proportionally, eventually yield will plateau as density increases, yield can be increased at the same density by increasing the limiting resource
self thinning rule
- describes the interaction between biomass and density
- self-thinning line describes a boundary towards which plants can grow
- B (biomass)= C N (# of indiv) to the power of -0.5 (negative exponential decline in size as you increase density
stocking
the number of trees per unit area compared with the desired number for best growth and management
understocked
unused growing space, trees are large and density is low
overstocked
- suppression, trees are small and density is high
commercial thinning
intermediate harvest in immature stands, trees have reached marketable size and all or some of the trees are extracted for useful products
non commercial thinning
cutting poor quality and crowded trees from a stand, no income
factors influencing regeneration
seed bed (e.g. the right microenvironment), seed supply (e.g. good quality seed trees), environment (e.g. light, moisture)
high vs low forest
high- sexual reproduction, seeds
low- asexual reproduction, stump and root sprouts
Hutchison’s niche concept
range of physical and biological conditions required for a species to maintain or increase its population
fundamental niche
the set of conditions required for a species to survive without competition
realized niche
the impact of other factors (environment, competition) on a species’ fundamental niche (its actual niche)
regeneration niche
the set of conditions required for a species to establish and pass through its juvenile phase
persistance niche
the niche that allows a species to persist and survive over time
reid’s paradox
observation that plant ranges shifted at a faster rate than seed dispersal normally occurs, possibly explained by jump dispersion (long distance movements, e.g. water currents)
Janzen conell escape hypothesis
highest density of seeds near the parent, best seedling survival rate further from the parent
assisted migration
- an approach to mitigate climate change my intentionally moving species to climatically suitable locations outside their natural range
- species rescue- AM to prevent extinction
- forestry- AM to maintain forest healthy and productivity
natural regen
- suitable for sites with:
- available propagules or advance regen
- effective dispersal or vegetative spread
- suitable seed bed
- window of suitable conditions
- pros: simple, inexpensive, matched to site conditions
- cons: variable, no control over species, may have to delay harvest
artificial regen
- necessary on site that:
- are not suitable of natural regen
- have different management goals
- pros: control over species, repeatable, control over harvest timing
- cons: difficult, expensive, impractical in remote areas
mixed regen
- pros: good on sites that have failed natural regen, some control, intermediate costs
- cons: site just may be poor quality, investments to control competition
enrichment planting
adding a particular species that is missing from the stand
reinforced planting
enhancing natural regeneration with planted stock
exotic species
- any species growing outside its normal range, including GMOs, artificial hybrids, and imported species
- easy propagation, rapid growth, resistance to local diseases and pests, shorter rotations, risk of invasion
site quality components
- based on a hierarchy of factors (climate, flooding, anthropogenic, freezing, etc.)
- stand level productivity is largely driven by gradients of moisture and nutrients
site index
- the avg height of dominant/codominant trees of an even aged stand at an index age, requires height: age curves
- Pros: easily applied, independent of competition
- Cons: restricted to even aged stands, cannot be applied to suppressed trees
phytocentric
- classification based on plants
- e.g. site index, indicator species
geocentric
- classification based on the earth
- e.g.climate, topography
phytogeocentric
- classification incorporating plants and earth characteristics
- e.g. ELC uses substrate characteristics and canopy composition and dominance to identify unique ecosites
