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Ecosystems and climate change > V5 > Flashcards

V5 Flashcards

1
Q

Structural features of the vegetation:

A
  • Vegetation can be described by different characteristics:
    • height of vegetation cover
    • density of vegetation cover
    • root penetration depth / intensity
    • species composition !!!
    • spectrum of life forms !!!
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2
Q

Structural features of the vegetation:

A
  • in the course of evolution, a large number of species have evolved in adaptation to very different site conditions
  • but at the same time only a small number of life and growth forms have developed

⇒ ​genotypic differences + similar appearance and function in the ecosystem (= ecological equivalence)

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3
Q

Structural features of the vegetation:

A
  • Description of a plant stand by:
    • species composition > plant communities
    • spectrum of life forms > plant formations

⇒ Plant formations give information about abiotic environmental conditions by their shape = physiognomic‐ecological vegetation units

⇒ different classification systems

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4
Q

Life and growth forms:

A
  • includes total habitus (size, shape, outline) and life span
  • plants: especially the shape of the leaves, the type of branching, the degree of lignification or the location of the renewal buds
  • animals: additionally the predominant nutrition, the degree of the mobility or prominent behaviors
  • Life forms after RAUNKIAER
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5
Q

Life forms after Raunkiaer:

A
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6
Q

Ecosystem characteristics:

A
  • Ecosystem turnover
  • Growth or defense (primary vs. secondary metabolism)
  • Plant interactions (competition, mutualism, niches, resilience, valence)
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7
Q

Turnover:

A
  • Net primary production (NPP) depending on site conditions:
  1. duration of the vegetation period
  2. global radiation
  3. air temperature during vegetation period
  4. water availability during vegetation period
  5. availability of mineral nutrients
    1. ‐ 4. climatic
  • further turnovers:
    • animal feed (=secondary production)
    • Litter decomposition
    • Humification
    • Mineralization
  • Net ecosystem exchange (NEE)
  • Ecosystem respiration:
    • Reco = CO2 release from soil + plant

⇒ NEE = GPP ‐ Reco

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8
Q

Change in primary production, biomass growth, litter and respiration:

A
  • Ecosystems are dynamic, longest dwell time in the mature phase
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9
Q

Model scheme of a natural/near‐natural ecosystem:

A
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10
Q

Primary production:

photosynthesis and respiration

A
  • light can be the limiting factor
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11
Q

Phytomass and primary production in forest systems:

A
  • esp. assimilation areas (LAI)
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12
Q

Primary production and evapotranspiration:

A
  • Water use efficiency (g formed dry substance / liter of transpired water)
  • Relation between production and water consumption
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13
Q

Secondary production (animal feed):

A
  • Animals:
    • heterotrophic creatures
  • nutrition directly or indirectly from organic products of primary producers
    • Consumers
    • Secondary producers
    • Biofages (live substance eaters):
      • herbivores, carnivores, omnivores
    • Dead substance eaters:
      • detrivors ( ⇒ together with bacteria / fungi (saprobionic plants): decomposers)
    • quantitative importance of biophages:
      • a few percent of the above‐ground phytomass eaten by herbivores
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14
Q

Four main groups of heterotrophic organisms:

A
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15
Q

Mineral turnover:

A
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16
Q

Primary and secondary metabolism:

A
  • Trade‐off between primary and secondary metabolism
  • what is put into defense is no longer available for growth
  • Secondary metabolites often “expensive“
17
Q

Plant defense:

A
  • Response to stress caused by environmental conditions (pests, climate, air pollution, scarcity of resources, competition, …)
  • New production of secondary metabolites
  • Supply of secondary metabolites
  • “Toxins”
  • “Warning signals”
  • “Calls for help”
  • Triggering of numerous functions (e.g. maturation)

⇒ not absolutely necessary for cell survival but useful or necessary for the whole organism

18
Q

Plant defense, Example:

desert mugwort (Wüsten‐Beifuß) and wild tobacco

A
  • in one group mugwort pruned, other group unchanged
  • emission of VOCs
  • tobacco near the pruned mugwort plants switches metabolism to defense
  • significantly less feeding damage by locusts
  • “eavesdropping” on neighboring plants / species
19
Q

Interaction of individuals of the same or different species:

A
  • Competition
  • Mutualism (mutual benefit)
  • Dependence on environmental conditions

⇒ Result: site‐specific species clusters

⇒ Plant communities and formations

20
Q

Ecological niche:

A
  • The entity of environmental factors that a uniform group of plants or animals (e.g. species) needs for their survival
  • biotic and abiotic factors combine to form a multidimensional hyperspace
  • functional relationship between a species and the ecosystem
  • within the niche space: competition, mutualism, symbioses

fundamental niche ⇔ realized niche

21
Q

Competition:

A
  • nteraction of organisms (of the same or different species) based on competition for limited resources
  • intra‐ and interspecific competition
  • mind‐experiment: pure vs. mixed culture
  • Picture:
    • Species 2 could also grow under extreme conditions, but is displaced by more competitive plants under these conditions
22
Q

Physiological valence:

A
  • every plant species can exist from its physiological constitution under wide ranges of environmental conditions

⇒ physiological range of existence / physiological valence

  • depending on the intensity of the influencing factor, different growth and distribution
  • range of highest production output: physiological optimum
23
Q

Ecological valence:

A
  • in case of occurrence of several species: mutual displacement/enforcement from more or less large parts of the physiological area of existence ⇒ ecological subsistence area / ecological valence
  • ecological optimum
  • ecological and physiological optimum coincide only in a few cases (mostly at the physiological edge)
  • misleading or wrong: “drought loving”, “in need of warmth”, “lime seeking”
  • species only more competitive ⇒ “drought‐bearing”
24
Q

Effects of competition:

A
  • intraspecific competition for water, nutrients and radiation
  • e.g. same total biomass production with different numbers of individuals of the same species (e.g. three or six Lolium perenne and three Daucus carota plants)
  • die off of the “weak” individuals ⇒ Selection of the best adapted individuals ⇒ Optimization of the genetic adaptation of the species
  • interspecific competition
  • e.g. three Lolium and three Daucus plants
  • Lolium biomass almost as in pure culture
  • Daucus biomass only at about 10% of the possible biomass
  • total biomass (Lolium + Daucus) same as before
  • with a three‐week growth advantage of Daucus:
    • Lolium only 40%
  • at three‐week growth advance of Lolium:
    • Daucus practically at 0
  • Adaptation to competition:
    • little energy in generative apparatus, more in height growth
  • e.g. with Daucus ahead:
    • Lolium compared to normal growth 40% stalk and leaf biomass, only 20% ear biomass (few seeds) ⇒ less offspring ⇒ extinction after some generations
  • Competition for nutrients and water underground, light above ground

⇒ Plant individuals recognize competing individuals very early via their photoreceptors (e.g. by the red/far red ratio)

25
Q

Mutualism (mutualistic symbiosis):

A
  • Interrelation between living beings of two species
  • at least one partner benefits compared to living alone, the second partner is at least not affected
  • Increase of the competitive strength
  • Colonization of more extreme habitats
  • Improvement of absorption of water and minerals
  • Making nutrients available from deeper layers
  • Water storage in cushions

⇒ positive interaction

  • Examples:
    • Central European forest trees and mycorrhiza
    • organization form of lichens (algae + fungi) ⇒ ‐196°C to +70°C
26
Q

Plant interactions:

A
  • each plant individual is involved in a permanent network of relationships between all stand individuals
  • competition is essential relationship
  • but also mutual support
27
Q

Influence of plants on environmental variables:

A
  • plants influence existential requirements of other species but also of the own species (rejuvenation)
  • light / radiation:
    • strong reduction ⇒ strong selection of species due to lack of light
  • precipitation:
    • interception, fog scavenging ⇒ increase, decrease or redistribution in the stand
  • soil water content:
    • by evapotranspiration lowering of the groundwater level ⇒ drying of the upper soil layers
  • soil nutrient content:
    • conifers ⇒ acid tolerant plants are grown; Robinia ⇒ N cycle
28
Q

Ecogram:

29
Q

Ecosystem characteristics:

dynamic equilibrium

A
  • quasi-stationary state of an ecosystem during an observation period (inputs and outputs of energy and matter in equilibrium)

Ecosystems and climate change (12 decks)

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