Terrestrial Ecology Samenvatting
H1: Intro & carbon cycle
1.1: Components of ecosystems
Ecology = Study of interactions among organisms & their environment
Ecosystem = Ecological system containing all organisms occurring in area & physical environmental factors with which
they interact.
There are different spatial scales => example:
• Global ecosystem (5,000 km) => how does C loss from plowed soils
influence global climate?
• Watershed (10 km) => how does deforestation influence water supply
to neighboring towns?
• Forest ecosystem (1km) => how does acid rain influence forest
productivity?
• Endolithic ecosystem (1mm) => What are biological controls over rock
weathering?
Where does 1 ecosystem stop & other starts? => Ecosystem boundaries can be based on
• Structural criteria = physical boundaries
o Geomorphological => topographic boundaries (aquatic / terrestrial)
o Physico-chemical => thermoclines, chemoclines (fresh / salt water)
o 3D => 3D borders (soil vs forest canopy)
o Biological => physical habitat boundaries (forest / grassland)
• Functional criteria = changes in degree of exchanges in matter & energy or interactions. Boundaries are drawn
at locations with:
o relatively little exchange of matter & energy
o weak interactions between species
o limited movement of organisms & genes
Is this an ecosystem? => Yes, cause ecosystem needs to function on its own
(processes), nutrients that can be turned into something else, … . You need
decomposition, so elements can be taken up again & primary producents
(here these are mosses).
1.2: Ecosystem components
Abiotic factors = Water, Minerals, Gasses (CO2, O2, N2), … => We are
interfering with these factors (consuming water,…) .
Biological factors:
• Species
• Functional groups of species
• Interactions among species
• Trophic interactions
Example: Soil food web of corn field => Seems like nothing is happening there, yet ...
Food webs with trophical intractions => Most energy in ecosystems flows through detrital chain & not grazing chain.
,Factor time = now, Seasons, Succession, Migration, Evolutionary history & Geological history
During succession, soil development takes place. Primary Succession takes place after glaciation,
volcanic activity or landslides, where plants are colonizing newly exposed substrate. Stages:
• Bare rock → lichens, mosses → Soil formation → Grass establishment → Shrubs → Mature
vegetation (forest or grassland)
=> Succession shows that soil & vegetation co-develop, with feedbacks that alter water retention,
erosion, & nutrient accumulation
Each soil layer (= horizons) has biological, chemical, & physical properties affecting plants
& nutrient cycling. Thickness of horizons depends on duration of weathering process (age
of soil) & it’s color depends on material type of (rock). Weathering is higher in young soils
than in soils that have been weathered for centuries (tropic soils).
1st horizon = organic layer => it’s thickness depends on decomposition rate
• Slow decomposition = thick layer
• Fast decomposition = thin layer
During last glacial period, temperate zones were covered in ice & tropical soils weren’t => their soil is much older &
nutrient richer.
Plants don’t take everything & parts are leached into ground. => Soil Cation Exchange
Capacity (CEC) = Organic matter particles with negative charges attracts cations (Ca²⁺,
Mg²⁺, K⁺, Na⁺), which causes exchange of nutrients with plant roots & leaching losses (=
downward movement of ions). CEC determines nutrient retention & soil fertility.
Types of mycorrhizal associations shift over soil development.
• Early soils => AM fungi (arbuscular mycorrhizae)
• Intermediate => woody plants with ectomycorrhizal & ericoid fungi
• Old, highly weathered soils => Cluster-root species or non-mycorrhizal species
with adaptations for extremely poor soils.
Amount of C, P & N present & form in which they are present during succession
changes:
• P-availability declines with soil age => P isn’t present in air, so it has to be
there with start of succession.
• N-availability increases early, then can decline depending on system
1.2.1: Evolutionary history
Nutrient Network (NutNet) = global research cooperative on > 100 sites => so you can make conclusions on global
scale.
They made Herbivory × Nutrients Experiment => field experiment, where at each site there are pots with certain set
up
, • Herbivory => some pots with fences to prevent vegetation is consumed by herbivores.
• Nutrient additions => some pots received N, P, K, other micronutrients, or
combinations
• Multiple replicates per treatment => where they measure biomass, species richness &
aboveground net primary production (ANPP)
=> Herbivores & nutrient availability interact to shape plant communities. Effect of
herbivores on plant richness & diversity depends on evolutionary history of site.
• Only higher plant species diversity in grazed sites at areas where plant species pool are
adapted to high grazing intensity. Less plants → more light to ground → lot’s of plants
can grow.
• If plants are consumed by herbivores & there is no reduction, it means they’re adapted to being
eaten.
Evolutionary History & Fertilization Effects on plant productivity, species richness & nutrient use shows
that long evolutionary histories tend to stabilize ecosystem function.
Exotic species show similar response to grazing exclusion in short evolutionary history sites as they do in
long evolutionary history sites (where they generally come from).
1.2.2: Stability & resilience
Stability = response of ecological systems to disturbances
Resilience = ability to recover after disturbance
Most ecosystems have 1 stable state. Multiple stable states = property of ecosystems that multiple stable
states can exist under same environmental conditions.
Hysteresis = relationship between cause & effect depends on magnitude of cause & direction in which cause takes
place (AKA pathway of degradation ≠ pathway of recovery).
Example: Hysteresis or alternative stable states in shallow lake
• If P increases (forward switch = red dots) => vegetation collapses into turbid, algae-
dominated state.
• Reducing P doesn’t immediately restore vegetation, recovery will only happen at much
lower P (Backward switch = black dots).
1.3: Why care about ecology or ecosystems?
Knowledge of ecology & ecosystems provides us with basic insight into functioning of earth as system. Ecosystems
provide goods & services for people. Human activities are changing ecosystems on large scale & Earth as system.
Example: Planned road threatened to curtail migration in Serengeti & would have
reduced wildebeest population from 1.3 to 0.3 million. => Because animals follow
patterns of primary production, caused by rain. 1 side of Mara river has more rainfall
than other during certain time of year & vice versa. Reduction in migration would
lead to lots of vegetation overgrazed at 1 side & other not consumed. These not
consumed will be burned, & N will go into air etc. Human land use (roads,
agriculture, settlements) intersects with major wildlife ecosystem & migration
system.
, 1.4: Carbon cycle
Global Terrestrial C-Cycle => C moves through terrestrial ecosystems via pools &
processes:
1. Atmospheric CO₂ = primary C source => Taken up by plants & algae through
photosynthesis, forming Gross Primary Production (GPP).
2. Part of GPP is used for plant respiration, releasing CO₂ back to atmosphere.
3. Remaining C (= Net Primary Production (NPP)), supports plant growth.
4. Animals consume these plants, part of this C is incorporated C into biomass &
other part is lost via respiration, excretion, or death (feeding decomposers).
5. Dead plant material, animal waste, & other organic matter enter soil organic
matter (SOM) pool. Microbes decompose this material, releasing CO₂ (microbial
respiration) or CH₄ under anaerobic conditions.
6. Human & natural extractions => Harvesting of biomass (such as crops, timber)
removes C from ecosystem.
=> CO₂ enters ecosystems via photosynthesis → moves through plants, animals, & soil
→ leaves via respiration, decomposition, fire, & leaching.
1.4.1: Net Ecosystem Production (NEP)
Net C accumulation in ecosystem = Balance between C inputs & outputs =
Net Ecosystem Production (NEP) = Balance between C inputs & outputs => NEP = GPP –
all C losses(respiration plant, herbivores, loss via disturbance & leacing,…).
• NEP > 0 => ecosystem is C sink = accumulates C
• NEP < 0 => ecosystem is C source = releases C
Plant activity affects local CO₂ dynamics within canopy.
• During day it decreases around vegetation => photosynthesis lowers CO₂ concentration (due
to CO₂ uptake) & visible as low-CO₂ zones near leaves.
• During night it increases in canopy layer => respiration dominates (no photosynthesis), leading
to higher CO₂ near ground.
There is constant concentration just above forest floor due to microbial respiration.
Seasonal variation in C Exchange (NEP, GPP, Ecosystem Respiration) for ecosystem:
• GPP (Gross Primary Production) = Total C fixed by photosynthesis => peaks in summer
• Reco (Ecosystem Respiration) = Total C released via respiration => whole year, but increases in
summer
• NEP (Net Ecosystem Production) = Difference between GPP & Reco.
o When GPP > Reco => C uptake = ecosystem is C sink → only in summer
o When GPP < Reco => C loss = ecosystem is C source
=> Ecosystems alternate between C sinks & sources depending on season.
Example: Annual course of CO2 concentration in Barrow, Alaska (USA) are high in winter &
low in summer => due to big consumption of CO2, as plants are alive
1.4.2: Global scale of C – cycle
Global Carbon (CO₂) Budget shows that:
• Anthropogenic Sources = fossil fuels, land-use change
• Sinks = ocean uptake, terrestrial biosphere, atmosphere
Net imbalance = +2,2 Pg C yr⁻¹ => net positive C imbalance, meaning that fraction
of CO₂ remaining in air each year
H1: Intro & carbon cycle
1.1: Components of ecosystems
Ecology = Study of interactions among organisms & their environment
Ecosystem = Ecological system containing all organisms occurring in area & physical environmental factors with which
they interact.
There are different spatial scales => example:
• Global ecosystem (5,000 km) => how does C loss from plowed soils
influence global climate?
• Watershed (10 km) => how does deforestation influence water supply
to neighboring towns?
• Forest ecosystem (1km) => how does acid rain influence forest
productivity?
• Endolithic ecosystem (1mm) => What are biological controls over rock
weathering?
Where does 1 ecosystem stop & other starts? => Ecosystem boundaries can be based on
• Structural criteria = physical boundaries
o Geomorphological => topographic boundaries (aquatic / terrestrial)
o Physico-chemical => thermoclines, chemoclines (fresh / salt water)
o 3D => 3D borders (soil vs forest canopy)
o Biological => physical habitat boundaries (forest / grassland)
• Functional criteria = changes in degree of exchanges in matter & energy or interactions. Boundaries are drawn
at locations with:
o relatively little exchange of matter & energy
o weak interactions between species
o limited movement of organisms & genes
Is this an ecosystem? => Yes, cause ecosystem needs to function on its own
(processes), nutrients that can be turned into something else, … . You need
decomposition, so elements can be taken up again & primary producents
(here these are mosses).
1.2: Ecosystem components
Abiotic factors = Water, Minerals, Gasses (CO2, O2, N2), … => We are
interfering with these factors (consuming water,…) .
Biological factors:
• Species
• Functional groups of species
• Interactions among species
• Trophic interactions
Example: Soil food web of corn field => Seems like nothing is happening there, yet ...
Food webs with trophical intractions => Most energy in ecosystems flows through detrital chain & not grazing chain.
,Factor time = now, Seasons, Succession, Migration, Evolutionary history & Geological history
During succession, soil development takes place. Primary Succession takes place after glaciation,
volcanic activity or landslides, where plants are colonizing newly exposed substrate. Stages:
• Bare rock → lichens, mosses → Soil formation → Grass establishment → Shrubs → Mature
vegetation (forest or grassland)
=> Succession shows that soil & vegetation co-develop, with feedbacks that alter water retention,
erosion, & nutrient accumulation
Each soil layer (= horizons) has biological, chemical, & physical properties affecting plants
& nutrient cycling. Thickness of horizons depends on duration of weathering process (age
of soil) & it’s color depends on material type of (rock). Weathering is higher in young soils
than in soils that have been weathered for centuries (tropic soils).
1st horizon = organic layer => it’s thickness depends on decomposition rate
• Slow decomposition = thick layer
• Fast decomposition = thin layer
During last glacial period, temperate zones were covered in ice & tropical soils weren’t => their soil is much older &
nutrient richer.
Plants don’t take everything & parts are leached into ground. => Soil Cation Exchange
Capacity (CEC) = Organic matter particles with negative charges attracts cations (Ca²⁺,
Mg²⁺, K⁺, Na⁺), which causes exchange of nutrients with plant roots & leaching losses (=
downward movement of ions). CEC determines nutrient retention & soil fertility.
Types of mycorrhizal associations shift over soil development.
• Early soils => AM fungi (arbuscular mycorrhizae)
• Intermediate => woody plants with ectomycorrhizal & ericoid fungi
• Old, highly weathered soils => Cluster-root species or non-mycorrhizal species
with adaptations for extremely poor soils.
Amount of C, P & N present & form in which they are present during succession
changes:
• P-availability declines with soil age => P isn’t present in air, so it has to be
there with start of succession.
• N-availability increases early, then can decline depending on system
1.2.1: Evolutionary history
Nutrient Network (NutNet) = global research cooperative on > 100 sites => so you can make conclusions on global
scale.
They made Herbivory × Nutrients Experiment => field experiment, where at each site there are pots with certain set
up
, • Herbivory => some pots with fences to prevent vegetation is consumed by herbivores.
• Nutrient additions => some pots received N, P, K, other micronutrients, or
combinations
• Multiple replicates per treatment => where they measure biomass, species richness &
aboveground net primary production (ANPP)
=> Herbivores & nutrient availability interact to shape plant communities. Effect of
herbivores on plant richness & diversity depends on evolutionary history of site.
• Only higher plant species diversity in grazed sites at areas where plant species pool are
adapted to high grazing intensity. Less plants → more light to ground → lot’s of plants
can grow.
• If plants are consumed by herbivores & there is no reduction, it means they’re adapted to being
eaten.
Evolutionary History & Fertilization Effects on plant productivity, species richness & nutrient use shows
that long evolutionary histories tend to stabilize ecosystem function.
Exotic species show similar response to grazing exclusion in short evolutionary history sites as they do in
long evolutionary history sites (where they generally come from).
1.2.2: Stability & resilience
Stability = response of ecological systems to disturbances
Resilience = ability to recover after disturbance
Most ecosystems have 1 stable state. Multiple stable states = property of ecosystems that multiple stable
states can exist under same environmental conditions.
Hysteresis = relationship between cause & effect depends on magnitude of cause & direction in which cause takes
place (AKA pathway of degradation ≠ pathway of recovery).
Example: Hysteresis or alternative stable states in shallow lake
• If P increases (forward switch = red dots) => vegetation collapses into turbid, algae-
dominated state.
• Reducing P doesn’t immediately restore vegetation, recovery will only happen at much
lower P (Backward switch = black dots).
1.3: Why care about ecology or ecosystems?
Knowledge of ecology & ecosystems provides us with basic insight into functioning of earth as system. Ecosystems
provide goods & services for people. Human activities are changing ecosystems on large scale & Earth as system.
Example: Planned road threatened to curtail migration in Serengeti & would have
reduced wildebeest population from 1.3 to 0.3 million. => Because animals follow
patterns of primary production, caused by rain. 1 side of Mara river has more rainfall
than other during certain time of year & vice versa. Reduction in migration would
lead to lots of vegetation overgrazed at 1 side & other not consumed. These not
consumed will be burned, & N will go into air etc. Human land use (roads,
agriculture, settlements) intersects with major wildlife ecosystem & migration
system.
, 1.4: Carbon cycle
Global Terrestrial C-Cycle => C moves through terrestrial ecosystems via pools &
processes:
1. Atmospheric CO₂ = primary C source => Taken up by plants & algae through
photosynthesis, forming Gross Primary Production (GPP).
2. Part of GPP is used for plant respiration, releasing CO₂ back to atmosphere.
3. Remaining C (= Net Primary Production (NPP)), supports plant growth.
4. Animals consume these plants, part of this C is incorporated C into biomass &
other part is lost via respiration, excretion, or death (feeding decomposers).
5. Dead plant material, animal waste, & other organic matter enter soil organic
matter (SOM) pool. Microbes decompose this material, releasing CO₂ (microbial
respiration) or CH₄ under anaerobic conditions.
6. Human & natural extractions => Harvesting of biomass (such as crops, timber)
removes C from ecosystem.
=> CO₂ enters ecosystems via photosynthesis → moves through plants, animals, & soil
→ leaves via respiration, decomposition, fire, & leaching.
1.4.1: Net Ecosystem Production (NEP)
Net C accumulation in ecosystem = Balance between C inputs & outputs =
Net Ecosystem Production (NEP) = Balance between C inputs & outputs => NEP = GPP –
all C losses(respiration plant, herbivores, loss via disturbance & leacing,…).
• NEP > 0 => ecosystem is C sink = accumulates C
• NEP < 0 => ecosystem is C source = releases C
Plant activity affects local CO₂ dynamics within canopy.
• During day it decreases around vegetation => photosynthesis lowers CO₂ concentration (due
to CO₂ uptake) & visible as low-CO₂ zones near leaves.
• During night it increases in canopy layer => respiration dominates (no photosynthesis), leading
to higher CO₂ near ground.
There is constant concentration just above forest floor due to microbial respiration.
Seasonal variation in C Exchange (NEP, GPP, Ecosystem Respiration) for ecosystem:
• GPP (Gross Primary Production) = Total C fixed by photosynthesis => peaks in summer
• Reco (Ecosystem Respiration) = Total C released via respiration => whole year, but increases in
summer
• NEP (Net Ecosystem Production) = Difference between GPP & Reco.
o When GPP > Reco => C uptake = ecosystem is C sink → only in summer
o When GPP < Reco => C loss = ecosystem is C source
=> Ecosystems alternate between C sinks & sources depending on season.
Example: Annual course of CO2 concentration in Barrow, Alaska (USA) are high in winter &
low in summer => due to big consumption of CO2, as plants are alive
1.4.2: Global scale of C – cycle
Global Carbon (CO₂) Budget shows that:
• Anthropogenic Sources = fossil fuels, land-use change
• Sinks = ocean uptake, terrestrial biosphere, atmosphere
Net imbalance = +2,2 Pg C yr⁻¹ => net positive C imbalance, meaning that fraction
of CO₂ remaining in air each year
