the ecosystem processes and the tools to manage them · tools to manage them | handout derived from...

UNIT II, COURSES 1 & 2

THE ECOSYSTEM PROCESSES AND THE TOOLS TO MANAGE THEM

| handout derived from ebooks two and three

Image: Matilda Essig

2 | © SAVORY INSTITUTE 2019

ECOSYSTEM BASICS

wat

er cycle

mineral cycle energy f ow community dyn

amic

s

The Four Ecosystem Processes

1. Water Cycle: The movement of water from the atmosphere to the soil or oceans, where it nourishes plant and animal life, and eventually back to the atmosphere.

2. Mineral Cycle: The movement of mineral nutrients from soil to plants and animals and back to soil again.

3. Community Dynamics (Succession): The ever-changing dynamics within a biological community. This process is ongoing due to the constant interplay of species, changing composition and changing microenvironment.

4. Energy Flow: The flow of energy from the sun to green growing plants, which convert the energy (through photosynthesis) to the food that fuels all life.

WATER CYCLETHE FLOW OF WATER THROUGH PLANTS AND SOILS

Rainfall Transpiration

SurfaceEvaporation

Evaporation from water sources

Runoff to rivers, lakes, and sea

Retention in Soil

Penetration to deeper crevices and underground water reservoirs

Underground flow to springs, rivers, seas

handout | THE ECOSYSTEM PROCESSES AND THE TOOLS TO MANAGE THEM | 3

QUESTIONS TO ASK IN DETERMINING THE

HEALTH OF THE WATER CYCLE ON YOUR LAND

� In most of your grassland, how wide is the plant spacing?

� As you look down between plants, how would you describe most of the soil surface: > Covered with litter, or bare

and exposed to rain and sun? > Capped, sealed and

impervious, or broken and porous?

� As you look between plants on slopes do you see little dams made of litter that has caught on plants and is leading to silt deposits behind each dam: > Do you see obvious signs

of water movement across the surface?

> Mostly plants with fine and narrow leaves or other signs of moisture conservation?

> Prevalence of microperennial grasses and or sedges in the grassland?

> Prevalence of plants with thick cuticles (skin) like cacti?

> Are most grass plants broad leafed and rapid growing?

> Do you notice shortly after rain that grass plants are dark green and growing rapidly or not?

Effective precipitation is that which soaks into the soil and becomes available to plant roots, insects and microorganisms, or replenishes underground supplies with very little evaporating from or running off the soil surface.

YOU DO THE MATHWhile even the healthiest land will not likely infiltrate all precipitation if you have a downpour or extremely fast thaw, this simple exercise shows the power that land managers have if they do improve the water cycle.

If 30 inches of rain were to fall on one acre of land, that would total 814,625 gallons of water. If a quarter of that water runs off, that is 200,000 gallons of water running off one acre of bare soil. If you multiply that figure by a million acres, the total amount of water running off would be over 200 billion gallons.

If you want to go metric, then remember this simple formula: if 1 mm of rain falls on 1 square meter of land that would total 1 liter of water. Thus, a 10,000-hectare ranch that only gets 250 mm (10 inches) of rain would get a total of 2,500,000 liters of water per hectare (10,000 square meters per hectare x 250 mm = 2,500,000).

That amount multiplied by 10,000 hectares is a great deal of water, as long as you keep it in the soil to grow plants and replenish underground water sources!


EFFECTIVE AND NONEFFECTIVE WATER CYCLES

Effective Water Cycle

Noneffective Water Cycle

LowLowLowLowHighHighHigh

Soil surface runoffSoil surface evaporation

Drought incidenceFlood incidence

Transpiration by plantsSeepage to underground reservoirs

Effectiveness of precipitation

HighHighHighHighLowLowLow


Image: U.S. Geological Survey

CO2CO2nutrient inputs

nutrient losses

respirationrespiration

decompositiondecomposition

organicmatter

weatheredbedrock

microorganisms

nitrogencalcium

carbon

uptake

MINERALS TO THE SURFACE

Stabilized Organic Matter (Humus) 33–50%

Decomposing Organic Matter (Active Fraction) 33–50%

Fresh Residue <10%

Living Organisms <5%

Components of Soil Organic Matter adapted from The Soil Biology Primer, by Elaine R. Ingham, USDA Natural Resource Conservation Service http://soils.usda.gov/sqi/concepts/soil_biology/soil_food_web

MINERAL CYCLE

MAXIMIZING THE CYCLE OF NUTRIENTS THROUGH PLANTS AND SOILS

The Soil Food Web

PlantsShoots and roots

NematodesRoot-feeders

NematodesFungal- and

Bacterial-feeders

NematodesPredators

ArthropodsShredders

Birds

Animals

ArthropodsPredators

Organic MatterWaste, residue, and metabolites

from plants, animals, and microbesBacteria

FungiMycorrhizal fungi,Saprophytic fungi

ProtozoaAmoebae, flagellates,

and ciliates


GOOD MINERAL CYCLE POOR MINERAL CYCLESoil surface is porous and rich in

organic matterSoil surface is sealed or capped,

and low in organic matter

� �Surface litter cover is high,

and mature, decaying mulch rests on the soil surface

Surface litter cover is low, and immature, oxidizing litter

rests on the soil surface

� �Rapid turnover of plant material;

old vegetation breaks down readily

Slow plant material turnover, and slow breakdown of old vegetation

(often left standing and weathering)

� �Large numbers of surface insects

and microorganisms presentFew surface insects and microorganisms present

� �Close plant spacing;

very little exposed soilWide plant spacing;

large areas of exposed soil

� �Plant roots are abundant, with

good penetration on many levelsShallow plant roots,

many lacking deep penetration

� �Soil underground is also porous

(good crumb structure), with abundant underground life

Soil is more compacted (poor crumb structure), with reduced underground life

� �Low surface mineral loss, as

well as mineral loss to leachingHigh losses of minerals off surface

as well as losses to leaching

� �High turnover rate of mineral nutrients Low turnover rate of mineral nutrients


COMMUNITY DYNAMICS

THE NEVER-ENDING PATTERNS IN THE DEVELOPMENT OF BIOLOGICAL COMMUNITIES

The more complex and diverse communities become, the more stable populations within tend to be.

High

Numbers within a

population

Diversity ofSpecies

HighLowLow

Succession: The stages through which biological communities develop. As simple communities become ever more diverse and complex, succession is said to be advancing. When complex communities are reduced to greater simplicity and less diversity, succession is set back. If factors that set it back are removed, succession will advance once again.

ENERGY FLOW

MAXIMIZING THE FLOW OF SUNLIGHT ENERGY THROUGH OUR ECOSYSTEM

Energy loss

as heat

SUN

Above-ground

Energy from plants

Energy loss as heat

Energy from plants

Below-ground


1

Energy loss

as heat

SUN

6

5

4

3

2

Decay

Scavengers/decay

Further predators, including humans

Predators, including humans

Fish, birds, insects, reptiles, and mammals, including humans

Plant life on land and in water

Energy flow seen as two tetrahedrons joined at their bases (labeled A, B, C). We can increase the amount of energy stored in the above- and belowground bases (shown in the cross section) in three ways by increasing: the time during which vegetation can grow and the rate at which it grows; the density of plants on a unit of ground; and the leaf area of individual plants.

Soil Surface atPlane A, B, C

Density

AreaTime

A B

B

C

A

C


TOOLS TO MANAGE THE ECOSYSTEM PROCESSES

HumanCreativity

Technology Fire Rest Money and Labor

Living Organisms• Animal Impact• Grazing

FIRE AND THE BRITTLENESS SCALE

Very brittle Nonbrittle

Generally reduces the effectiveness of the water cycle; exposes soil and destroys litter. The lower the rainfall the greater the impact.

➤ WATER CYCLE ➤

Tends to damage water cycle by exposing soil;

effect is temporary due to better annual

distribution of humidity and more rapid

succession on bare surfaces.

Speeds the mineral cycle in the short term, converting dead material to ash; but it exposes soil.

➤ MINERAL CYCLE ➤

Appears to speed up cycling of nutrients,

although the effect is temporary.

In short term, increase diversity of species; repeated fires reduce diversity.

➤ COMMUNITY DYNAMICS ➤

In short term, increase diversity of species;

repeated fires reduce diversity.

Initially increases energy flow; in the long term, it reduces energy flow due to increased soil exposure leading to less effective water and mineral cycles.

➤ ENERGY FLOW ➤

Disrupts the energy flow in the short term,

but it recovers quickly; frequent fires tend to damage all four

ecosystem processes.

This summary assumes that the fire is followed by a period of rest, which is standard practice.


THE EFFECTS OF REST IN DIFFERENT BRITTLE AND NONBRITTLE ENVIRONMENTS

High rainfall brittle environment in Zimbabwe. Without grazing animals, the land would deteriorate.

Sheep grazing in a nonbrittle environment. If the tool of rest were applied, the grassland would revert to forest.

Dying, overrested plant in a brittle environment


REST (PARTIAL OR TOTAL) AND THE BRITTLENESS SCALE


Water cycle becomes less effective.

➤ WATER CYCLE ➤

Water cycle builds and maintains high levels of

effectiveness.

Mineral cycle becomes less effective.


Mineral cycle builds and maintains high

levels of effectiveness.

Biological communities decline and greater simplicity and instability ensue. The lower the rainfall, the greater the adverse effect.


Biological communities develop to levels of great diversity and

stability.

Declines significantly.

➤ ENERGY FLOW ➤ Reaches a high level.


ANIMAL IMPACT AND THE BRITTLENESS SCALE


Periodic high impact generally improves water and mineral cycles.

Low impact reduces water and mineral cycles below the land’s potential.

➤ WATER AND MINERAL CYCLE ➤

Periodic high impact tends to improve both

water and mineral cycles. However, while

it tends to sustain a grassland for example,

it may result in less effective water and mineral cycles than

possible in woodlands.

Low animal impact has little effect.

Promotes the advancement of biological communities on bare, gullied, or eroding ground; tends to maintain the biological community at grassland level, preventing shift to woody community.

Low animal impact or partial rest tends to produce bare ground.


Periodic high impact maintains grass root

vigor and discourages establishment of

woody plants and slows the shift to

woody communities.

Periodic high impact tends to build community complexity and improve water and mineral cycles, and as a result increases energy flow.

Low impact reduces energy flow below its potential. The shortfall becomes severe if compounded by the overgrazing of plants.

➤ ENERGY FLOW ➤

Periodic high impact tends to increase

energy flow, although when used to maintain

grassland in lieu of forest, energy flow

will never reach its full potential.

Low animal impact has little effect.


ANIMAL IMPACT VS OTHER TOOLS

Situation Potential use of other tools

Effects of animal impact

In a fairly brittle high rainfall environment overrest has allowed plants to accumulate several years of old material. Roots have suffered severe damage and the community has started to shift to forbs, shrubs, and trees where we want to maintain open grassland.

Fire would pollute the atmosphere, while exposing soil and invigorating many of the woody plants.Chemicals or machinery might clear the ground, but would not guarantee that plants would establish.

Periodic high animal impact, together with grazing (but not overgrazing) could remove old material, invigorate existing plants without exposing soil, create conditions for new plants to establish, and move the biological community away from noxious weeds or woody plants.

Leafy spurge, knapweed, snakeweed or some other noxious plant has invaded a piece of ground.

Thousands of dollars have already been spent attempting to use chemicals or machinery or other forms of technology to eradicate them.

Using continual doses of high animal impact, followed by well-planned recovery periods, cause the offending plants to diminish by moving succession beyond the stage that suits them.

Bare eroding ground is hastening the desertification process in an area.

One might fence off and seed this area at great expense.

Subject the area to periodic heavy animal impact by giving a large herd a few bales of hay. This excites them and concentrates them on that area. New plants can then establish on the broken, litter-covered ground, at no cost or lost production.

Erosion gullies whose steep banks offer no foothold to plants are spreading across an area.

One could use a bulldozer to slope the banks, chewing up more land, consuming diesel fuel, and polluting the air.

A herd of livestock or game animals attracted to the gully can break down the sharp cutting edges and create conditions for plant growth to heal them. The high animal impact, while fixing the gully also tends to correct the noneffective water cycle that caused the damage in the first place.


GRAZING AND THE BRITTLENESS SCALE


Enhances water and mineral cycles by maintaining healthier and more stable root mass, increasing microorganism activity and aeration, and producing plants with more shoots and leaves that later provide more litter.

➤ WATER CYCLE ➤

Will not expose soil, but cause even

denser cover; will thus enhance water

and mineral cycles in grasslands.


Enhanced by grazing in grasslands.

Maintains grassland communities, increases their diversity and covers soil, retards shifts toward woody species. Increases organic content, structure, aeration, and soil biological activity because more leaf and more roots are produced.


Because plant spacing is naturally close and

soil cover hard to damage; grazing tends to maintain grass root

vigor, soil life, and structure.

Increases energy flow by promoting vigorous root and leaf growth. Healthier, more massive root systems support millions of microbes and below ground life.

➤ ENERGY FLOW ➤

Grazing increases energy flow;

both above- and belowground in

natural grasslands and pastures.

Note: Overgrazing of grass plants tends to produce the opposite effects of regenerative grazing These effects, or tendencies, are difficult to isolate because overgrazing is commonly associated with prolonged time on the land, low density of animals and thus high partial rest. Generally, in brittle environments, partial rest tends to be more damaging to all four ecosystem processes than overgrazing of plants.


THEFEEDBACK

LOOP

PLAN MONITOR

CONTROLREPLAN

(assume wrong withenvironmental decisions)

HOLISTIC MANAGEMENT FRAMEWORK

WHOLE UNDER MANAGEMENT

HOLISTIC CONTEXT

ECOSYSTEM PROCESSES

ECOSYSTEM MANAGEMENT TOOLS

ACTIONS AND DECISION MAKING

CONTEXT CHECKS

MANAGEMENT GUIDELINES

FEEDBACK LOOP

Time Stock Densityand Herd E�ect

Cropping Burning PopulationManagement

Causeand

E�ect

MarginalReaction

GrossProfit

Analysis

Energy/MoneySource

and Use

GutFeel

SustainabilityWeak Link• Social• Biological• Financial

Objectives, Goals, Tactics, Strategies, PoliciesCustomary Selection Criteria (past experience, expert advice, research, etc.)

HumanCreativity

Technology Fire Rest Money and Labor

Living Organisms• Animal Impact• Grazing

(Statement of Purpose) — Quality of Life — Future Resource Base

Decision Makers — Resource Base — Money

Water Cycle Mineral Cycle Community Dynamics Energy Flow

PROCEDURES AND PROCESSES

Holistic PlannedGrazing

Holistic PolicyDevelopment

Holistic ResearchOrientation

Holistic FinancialPlanning

Holistic LandPlanning

the ecosystem processes and the tools to manage them · tools to manage them | handout derived from...

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