Forest Ecosystems Purdue Exam 2 2024

Evaporation

requires solar radiation, water layer near soil surface, increases w/wind and temp, decreases w/vegetation and finer soil texture

Transpiration

loss from leaves by vaporization of translocated water increases w/wind temp and light

Runoff

water that does not infiltrate

Hydrophytes

adapted to excessive water via internal cavities, spongy tissues, roots restricted to aerated surface soil, low oxygen requirement, pneumatophores (bring in air), guttation

Guttation

hydathode allows water to leave through root pressure, send it through leaves, example being rice

2 ways to deal with water deficits

escape or resist

Escape

xerophytes, desert annuals (stay as seeds until it is a wet time and then flower), opportunists, small size, high root:shoot ratio, complete life cycle quickly when water is available

Resist

avoidance or tolerance, water saver xerophytes (type one: succulent) or water spenders

Succulent

absorb water when available and store in parenchyma, vacuoles until needed, superficial or drought

Water spenders

accelerated water absorption, high internal water content despite high transpiration rates, stomata open during the day root adaptations, hydraulic lift, reduced permanent wilting point, dew absorption through foliage, may become water savers if necessary, ex creosote bush and mesquite

Water spender root adaptations

very high root:shoot ratios, large deep root systems, new roots explore, hydraulic lift

Tolerance tolerant xerophytes

high levels of solutes in cells and sap, low metabolic rate, easily suspended, ex mosses and lichens, resurrection plants

Whether a plant is an escaper or resister determined by

genetics

Animal adaptations to excessive water

terrestrial migration or nomadism, semi aquatic alternate breathing mechanisms and osmoregulation

Water deficit in animals

escape physically: migration, nomadism, Escape temporally:estivation, avoid physically: burrowing or nocturnal behavior, humidity control, impervious integument, Avoid temporally: drought resistant stages, Tolerate physically: water from food, utilization of metabolic water, internal lungs or spiracles, dry excretion

Osmoregulation

Osmoregulation is the process by which an organism maintains the balance of its internal fluids’ osmotic pressure, electrolyte concentrations, and water content, regardless of changes in the surrounding environment. This regulation is crucial for maintaining homeostasis and ensuring the proper functioning of cells, tissues, and organs

What is a gradient

the rate of increase or decrease of a variable magnitude, or the curve which represents it; as, a thermometric gradient

Environmental gradient

An ecological variable that increases or decreases across a spatial range and influences the distribution of species and composition of biotic communities

Ecotone

transition between two structurally different communities

We are living in what ecotone

woodland, transition between grassland and shrubland

Robert

one of the greatest contributors to the development of ways to measure gradients. He studied in the Smokies mostly

Why is it important to classify vegetation? (5 reasons)

better understanding of plant environment interactions, useful for land and natural resource management and planning, important for managing habitat for wildlife species, important for research and understanding long term and large scale phenomena such as climate change, facilitates communication about different ecosystems#

Early attempt at climatic classification was called the Koppen climate classification and involved what 5 climatic types

tropical rainy/humid, dry, humid mesothermal, humid microthermal, polar

Landform or physiographic classification

based on soils and landform

Advantages/disadvantages of physiographic classification

advantage: lends itself well to remote sensing, is based on permanent features. Disadvantages: does not typically apply well to classifying vegetation, have evolved to include vegetation

Two major assumptions of vegetation classification

natural vegetation groupings or communities occur across the landscape, and it is reasonable to separate a continuum of variation in vegetation composition and/or structure into a series of potentially arbitrary classes

Physiognomic classification

based upon structure and life form.

Formations in physiognomic classification are defined as

classes based upon growth form of dominant planst and the type of environment in which they grow

Associations in physiognomic classification are defined as

defined as a community of definite floristic composition within a formation

Classifications based upon dominance type

used in the national system of forest classification in the US, and in areas with diverse flora the selection of dominant species to define classes is arbitrary and does not provide a meaningful classification unit

Classifications based upon floristic composition have three basic types

those based upon ground vegetation (Finland and Baltic region), those based upon overstory vegetation (Canada and US) and those based upon the classification of the entire plant community (braun blanquet, Daubenmire)

The Braun Blanquete approach

this approach recognizes the reality of continuous species distributions, but emphasizes the interactions lead to relative discontinuities (or zones of separation) between communities. It also stresses that distinction between the abstract ideas of an association and a real plant community that is growing in a real physical environment, but is assigned to particular abstract class or association. These associations are separated based upon character species

Braun

Blaquete character species

The habitat type approach (Daubenmire)

vegetation is classified based upon differences in the overstory, the resulting units are subdivided based upon dominant shrub or herb species, units are named for dominant overstory and understory species, only climax associations are considered in the nomenclature, but seral variants are described, the climax associations are used to define habitat types

Eastern forests typically require a (blank) approach to type them

multifactor

The multifactor approach

multifactor classifications are based upon multiple ecosystem components including vegetation, topography, and edaphic (soil) characteristics. Multivariate statistical techniques have been widely used to create these classifications

Vertical structure

consequence of variations in the growth form of plants

Physiognomy

overall growth form of a community

Forest structure

canopy and lower canopy trees (tree layer), understory trees and shrub layer (shrub layer), ground cover (herbaceous layer), epiphytes (plants that grow on other plants without causing harm), lianas vines and woody climbers, thallophyte layer

Epiphytes

plants that grow on other plants without causing harm

Crown classes

dominant, codominant, intermediate, suppressed

Dominant trees

extend above the canopy, full light from above and sides

Codominant

general level of the canopy, light from above but less from sides

Intermediate

shooter subordinate trees, some light from above, none from sides

Suppressed

below canopy level, no direct light

Forest structure post disturbance

reorganization phase during disturbance, then aggradation phase, transition phase, steady state phase

Intermediate disturbance hypothesis

Joseph H. Connell proposed that disturbance is a prevalent feature that significantly influences community diversity. Proposed both high and low levels of disturbance would reduce diversity

Reorganization

high variability, new species, biomass begins to increase

Aggradation

all the biomass really starts to increase, different layers start to increase, productivity begins to be regained

Transition

forest growth begins to slow/decrease, competition begins, multiple species begin to emerge, cohorts and gaps emerge

Steady state phase

mature forest is chilling, pretty stable, most complex state

Time in disturbance

it is system dependent!

Environmental conditions

moisture, precipitation, temperature, light availability, soil, topography, etc.

Complexity of communities ranked least to greatest

desert, savannah, dry pine forest, mixed mesophytic forest, tropical rainforest

Symbiotic relationship

predominantly beneficial, lacking a negative effect on either species involved (mutualism and commensalism)

Mutualism

interactions where both partners benefit with or without continuous contact (examples: lichens have continuous contact, ohia trees and i’iwi bird in Hawaii aren’t in continuous contact)

Mutualism examples

mycorrhizal relationships, nitrogen fixing bacteria, ants tending to aphids, euglossine bee pollinating an orchid, fungus farming ants

FACE

free air carbon dioxide enrichment program

Nitrogen fixation

nodules containing rhizobium bacteria fix the nitrogen

Commensalism

benefits one but doesn’t hurt the other, (ex: cattle egrets, animals that live in the preexisting holes/cracks/crevices of trees)
Antagonistic

Nonconsumptive physical exploitation

no resources are directly consumed, but using the host for structural/physical support, can cause indirect negative impacts on the host (ex: cowbirdy, vines)

Consumptive physical exploitation

epidemic state, pathogen/parasite is newly introduced and spreads rapidly (rapid ohia death ROD, chestnut blight), endemic phase: stable relationship established or restored between parasite and host

Predation

duh, predator and prey

Herbivory

duh, little guy eat the plant

Antibiosis

inhibitory chemical interactions between species

Allelopathy

chemical inhibition between plants, example garlic mustard

Competition

interspecific competition occurs when two different species attempt to use the same resource when that resource is in limited supply, doesn’t occur when that resource is unlimited, can also occur if the resource is not in short supply but the two species’ use of said resource interfere with each other

Competitive exclusion principle

two species competing for the same resource cannot coexist indefinitely, at some point one is gonna go kapow

What is a gradient?

the rate of increase or decrease of a variable magnitude, or the curve which represents it; as a thermometric gradient

William Morris Davis idea

geographical cycle idea

Henry C Cowles idea

applied the idea of geographical cycle to vegetation in the Sand Dunes and came up with the idea of succession

Fredrick Clements idea

applied the work of Cowles and developed a broader theory of vegetation dynamics. This was based upon the organismal metaphor, which he described communities as SUPERORGANISM that change over time in very discrete ways culminating in a predictable endpoint or climax state

Henry Allen Gleason idea

argued that communities are the result of interactions between individual species and the environment in combination with change historical events. His was known as the INDIVIDUALISTIC MODEL

Clement vs Gleason

Clement had closed communities, Gleason had open communities

Robert Whittaker

the continuum theory of the community. He found that species were distributed along environmental gradients and true ecotones were rare

Margaret Davis

found that many species that co

Hemlock and maple in the UP

migrated further and further northward, as did oak and chestnut in the northeast

Modern synthesis (6 things)

community structure is a population process, communities are sections of continuous gradients, communities have some directionality and predictability, communities are strongly influenced by historical effects, communities rarely develop a stable climax, communities are dynamic and influenced by disturbance

Pattern and process

much of the contemporary study of forest communities centers around pattern and process. Pattern relates to the spatial distribution of communities across landscapes, process comprises the ecosystem functions (processes) that influence the spatial distribution (pattern) of forest communities

Why was the balance of nature view attractive to ecologists?

if it was true, it presented a view where most aspects of communities and the ecosystems in which they preside would be highly predictable and stable. Sadly, it’s not true

Paradigm

a constellation of concepts, ideas, approaches, and principles shared and used by a scientific community to define research problems and solutions

The equilibrium paradigm

focused on closed, self

The non equilibrium paradigm

populations, communities, and ecosystems may be far from equilibrium because of variable frequencies of disturbance and climatic fluctuations

Simberloff

pessimistic about the limitations of ecology!

Franklin

there is no truth in ecology, man was an existentialist

Hall

talked about how physicists couldn’t work with hungry electrons

Equilibrium

Communities in which species abundances remainCommunities in which species abundances remain

Non equilibrium

Communities in which species abundances fluctuate

Lb Slobodkin

optimistic about the limitations of ecology

Nelson G Hairston

less optimistic about the limitations of ecology

Charles Elton

the balance of nature does not exist, and perhaps has never existed… the resultant confusion is remarkable

Equilibrium

communities in which species abundances resin constant or stable over time due to biological processes such as somcpetitioin predation
Disturbance

Forest development

focuses on stand structure versus provesses, development pattern is divided into 4 stages

Stand initiaion

recriutment/ regeneration of early successional vegetation, high resource availability, low biomass

Stem exclusion phase

high competition for resouces, maximum lai, self, thinning

Understory reinitiation

gaps in the canopy form to procide light for the understory, diverstiy of niches, increased coarse woody debris

Old growth

approaching steady state, species replacement, processes remain similar in magnitude

Kurt Vonnegut

if people think nature is their friend, then they sure don’t need an enemy

Poikilotherms

to maintain a tolerant and fairly consistent body temperature, cold blooded organisms rely upon behavioral adaptations

Homeotherms

escape the thermal restraints of the environment