Nur auf Docsity: Lade Ecosystem Ecology Anki Flashcards und mehr Übungen als PDF für Ökologie herunter!
describe four different network topologies (architectures)
1. Bus Topology (Architecture: A single central cable (bus) connects all devices (nodes) in the network.) 2. Star Topology (Architecture: All devices are connected to a central hub or switch. The hub acts as a central point for communication.) 3. Ring Topology (Architecture: Devices are connected in a circular configuration, with each device connected to two other devices). 4. Mesh Topology (Architecture: Every device is connected directly to every other device in the network, either partially or fully.)
Can internal ecosystem nitrogen cycling meet the nitrogen requirements to supply plant growth?
Yes, internal N cycling, through processes like decomposition, mineralization, and plant uptake , provides most of the nitrogen for plant growth.
However, it may not always be sufficient in nitrogen-limited ecosystems, where external inputs like biological N fixation or fertilizers are crucial
Compare P and K cycling in an ecosystem and highlight the differences
Phosphorus:
gained through weathering of rocks tied to decomposition easily lost through erosion and leaching
Kalium/ Potassium:
gained from weathering of minerals lost due to logging
P- cycling is mainly controlled by living organisms , while K- cycling depends more on non- living processes like rock breakdown (weathering).
Define network mean trophic level and its relationships with connectance
(MTL) average trophic position of all species or nodes in an ecological network
Higher connectance reduces distinct trophic levels , High connectance= species interact with multiple other species across different trophic levels (e.g., omnivores feeding on both plants and herbivores). This blurs the clear separation between producers, herbivores, and predators because energy flows in more complex patterns. As a result, it becomes harder to categorize species into distinct trophic levels. -> Lower Connectance Leads to Clearer Trophic Hierarchies , low connectance= species have fewer interactions This creates a hierarchical structure where distinct trophic levels are clearly identifiable, from primary producers to apex predators.
Explain the direct species interaction model of succession (3) Facilitation-tolerande- inhibition model
Facilitation (+/+) : Early species improve conditions for later species (e.g., soil enrichment). Tolerance (o/o) : Later species are unaffected by earlier ones but outcompete them over time. Inhibition (-/-) : Early species prevent later species from establishing unless disturbed.
Explain the life-history-trade-off model of succession
Focus : Species traits like dispersal, growth, and survival drive succession. Stages :
Primary Colonizers : Disperse well, tolerate harsh conditions, grow slowly. Secondary Colonizers : Rapid growth, high seed production, early reproduction. Climax Species : Slow- growing, high competition ability, long lifespan.
How can disturbance affect succession?
Disturbance (e.g., fire, storms, floods) resets succession by altering ecosystems and changing community composition and function. Herbivory can either speed up or slow down succession, depending on how herbivores interact with the species present.
How can network robustness be studied?
Node/Link Removal Simulations Error vs. Attack Tolerance: Comparing the effects of random node removal Resilience Modeling : Using mathematical or computational models to predict robustness under different scenarios.
How can species richness affect ecosystem productivity? (3)
Niche complementarity : Different species utilize resources in complementary ways, increasing overall resource use efficiency and productivity. Facilitation : Some species can create conditions that enhance the growth of others, boosting productivity. Sampling effect : Ecosystems with more species are more likely to include highly productive species, increasing overall productivity. High species richness often leads to greater biomass and primary production because diverse communities better exploit available resources and adapt to environmental changes.
How can sustainable vegetable production look like without pesticides?
Alternative farming methods, including biological pest control and crop rotation , can reduce pesticide reliance while maintaining productivity and environmental sustainability.
How could agricultural practices be improved in terms of water cycling? (4)
Use water-efficient irrigation to save groundwater. Maintain plant cover to prevent soil erosion. Add compost to increase soil organic matter. Restore vegetation in degraded areas through reforestation.
How do Grime´s C-S-R strategy relate to succession?
C (Competitors) : Thrive in low-stress, low-disturbance environments. S (Stress-Tolerators) : Adapt to high-stress environments (e.g., nutrient-poor soils). R (Ruderals) (Unkraut) : Flourish in high-disturbance, low-stress settings with rapid growth and reproduction. Succession Trajectory : primary succession starts with a lot of stress-tolerators, moving then to ruderals In the early stages of secondary succession, R species (ruderals) dominate because of their ability to grow quickly in disturbed areas. moving then to stress tolerators
How does light availability and quality changes when passing through leaf or water?
light is scattered, reflected, transmitted or absorbed quality of light changes with depth in water -> reducing its intensity -> affects the efficiency of photosynthesis in aquatic plants
How does oxygen availability in soil affect nitrogen cycling in soil?
Oxygen is crucial for processes like nitrification , which converts NH₄⁺ (ammonium) to NO₃⁻ (nitrate).
Low oxygen levels (anoxic conditions) favor denitrification and anaerobic processes like anammox, leading to nitrogen loss as gas
How does plant cover affect water storage and cycling? (4)
Precipitation (rain) & Air Currents: Plants absorb energy, influencing weather. Evapotranspiration: Plants increase water evaporation and transpiration. Water Storage: Roots improve water infiltration; organic matter helps soil hold water. Runoff Prevention: Plants slow rain, reduce runoff, and prevent floods and erosion
How does primary and secondary succession differ?
Primary Succession : Starts with bare substrate; no soil present initially, slow Secondary Succession : Soil and biological remnants remain after disturbance, rapid
How does temperature influence carbon decomposition rates?
Higher temperatures generally accelerate carbon decomposition rates by increasing microbial metabolic activity.
How does the chemical composition of organic matter affect decomposition?
Organic matter rich in lignin decomposes more slowly , while simpler compounds like sugars and proteins decompose rapidly.
How does the facilitation- tolerance-competition model explain succession?
how species interact during succession in an ecosystem:
Facilitation : Early species enhance site conditions (e.g., nitrogen fixation). Tolerance : Later species tolerate lower resources, eventually dominating. Competition : Early species outcompete newcomers, except under disturbance.
How does the network structure of mutualistic networks differ from that of antagonistic networks?
mutualistic (+/+): Enhanced stability through nestedness, with generalist hubs, bipartite structure:
- typically involve two distinct groups of species, such as plants and their pollinators, with interactions occurring only between groups, not within them. antagonistic(+/-): hierachical, instability from modularity
How does water cycle in nature?
storage forms: vapour, liquid and solid transfer stages:
evaporation moisture transfer through atmospheric air precipitation (condensation) drainage (runoff)
infiltration and runoff: part of the precipitation soaks into soil, rest flows as runoff Evaporation and transpiration from plant surfaces return water back into the atmosphere, completing the cycle.
How is phosphorus gained, recycled and lost in ecosystems?
gained: through rock weathering , where phosphate ions are released into the soil. recycled:
within ecosystems through the biological cycle. Plants take up phosphorus, which moves through the food web. Decomposition of organic matter releases phosphorus. Phosphatase enzymes and organic acids help release bound phosphorus from organic and mineral sources.
lost: via leaching and erosion , which transport phosphorus into water bodies, where it can settle as sediment and become unavailable.
How is plant photosynthesis predicted to respond to elevated CO 2?
increase photosynthesis rates as it reduces photorespiration in C plants but it is nutrient limited and depends on light, temperature and water availability
How stable are different successional stages?
Climax Communities : final, stable stages of succession, where the ecosystem reaches a balance. More stable but can change with severe disturbances. Alternative Stable States : Ecosystems can settle into different stable states, depending on factors like initial conditions and disturbances. This means an ecosystem could end up in different types of balanced states over time.
How will climate change (hotter, dryer and more CO 2 ) affect C and C4 plants and why?
C3:
benefit from elevated CO 2 less efficient in extreme heat and drought
C4:
less efficient with elevated CO 2 since their photosynthetic process already minimizes photorespiration. more efficient in hot, dry conditions , maintaining higher water and nitrogen use efficiency.
What are alternate pathways in succession and why do they occur?
Different routes succession can take due to varying starting conditions , disturbances, or environmental changes , leading to multiple stable endpoints.
What are ecosystem process modulators? Give examples (3)
factors that influence ecosystem functions but are not consumed in the process. Examples:
pH levels regulate microbial activity in the soil. Temperature influences reaction rates in nutrient cycling. Oxygen availability affects decomposition and respiration rates.
What are the potential feedback effects of carbon decomposition on climate change?
Increased decomposition due to warming can release more carbon dioxide , creating a feedback loop that exacerbates climate change.
What developments affect ecosystem function during progressive succession (primary and secondary succession)?
Changes Over Time :
Improvement of: Soil and microclimate (e.g., temperature becomes more stable). interactions between species (competition, cooperation, mutual support). Vegetation grows in layers (like trees, shrubs, and grasses). -> fewer new plants grow -> few space for new species
What factors affect plant photosynthesis? (5)
light availability CO 2 concentration (higher levels generally enhance photosynthesis but can reduce stomatal conductance) temperature (extreme temperatures reduce enzyme activity and membrane stability) water availability leaf structure
What factors affect species richness in an ecosystem? (6)
Productivity : Ecosystems with moderate resource availability often support higher species richness due to balanced competition and niche availability. Habitat heterogeneity : Diverse habitats offer more niches, supporting a greater variety of species. Disturbance regime : Intermediate levels of disturbance (e.g., fires, floods) promote species coexistence by preventing dominance, while very high or low disturbance can reduce richness. Climate : Stable and favorable climates (e.g., tropical regions) support high species richness, while extreme or fluctuating climates limit diversity. Area size : Larger ecosystems generally harbor more species due to a wider variety of niches and resources (species-area relationship). Connectivity : High connectivity with other ecosystems facilitates migration and gene flow, increasing species richness.
What impact does the carbon-to- nitrogen (C:N) ratio have on decomposition?
A lower C:N ratio (more nitrogen available than carbon) typically accelerates decomposition because it provides sufficient nitrogen for microbial growth.
What is GPP?
Gross Primary Production the amount of chemical C-bound energy that primary producers create in a given time
e.g. photosynthesis
What is biological nitrogen fixation, where does it occur and what controls it?
the process by which nitrogen gas (N₂) is converted into ammonia (NH₃) by nitrogenase enzymes, often in symbiosis with plants.
Where it occurs : In symbiotic relationships (e.g., rhizobia with legumes), associative N₂ fixers in plant rhizospheres , and free- living bacteria in soils and decaying logs.
Controlled by :
High energy requirements. Sensitivity to oxygen Nutrient availability, especially phosphorus in some ecosystems
What is boron needed for and how is it cycled in a forest?
cell wall integrity, meristem activity overall plant growth
Cycle in a forest:
released slowly from rocks recycled through organic matter decomposition lost via leaching (acid and sandy soils) returned to soil through leaf litter logging can disrupt this cycle
What is chlorophyll fluorescence and how is it used to estimate global photosynthesis?
Chlorophyll fluorescense occurs when chlorophyll molecules absorb light and re-emit it at a longer wavelength used to estimate the photosynthetic activity by measuring the emitted light -> providing insight to plant health and global fluxes
What is compartmentalism regarding networks?
the division of the network into relatively independent sub- networks
What is diversity regarding networks?
number of species
What is dynamic stability?
ability of a system to return to a stable state or equilibrium following a disturbance, while allowing for fluctuations over time
What is ecological stoichiometry? Give an example. Why might it limit ecosystem response to changing conditions?
study of the balance of elements in organisms and ecosystems, reflecting their biochemical needs e.g. Litter C:N:P 3007:45:
Limitation : If a limiting nutrient (e.g., P) becomes scarce, it constrains the cycling of all nutrients, reducing the ecosystem's ability to adapt to changes like climate shifts or nutrient deposition.
What is ecosystem ecology? (3)
Study of interactions between organisms and their physical environment as an integrated system provide the link between biotic and abiotic systems incorporates humans and their activities
What is ecosystem retrogression, why does it happen?
A decline in productivity and ecosystem function due to long- term nutrient depletion.
Causes:
Chemical weathering and leaching remove nutrients (e.g., phosphorus). Nutrients may become trapped in unusable forms (e.g., occluded phosphorus).
What is ecosystem stability and how can species diversity/ richness affect it? "functional redundancy, response diversity"
Ecosystem stability refers to an ecosystem's ability to resist (resistance) or recover (resilience) from disturbances and maintain its functions over time.
Diversity-stability hypothesis : High species richness enhances stability because:
Functional redundancy : Multiple species perform similar roles, ensuring ecosystem functions persist if one species declines. Response diversity : Diverse species respond differently to environmental changes, reducing the risk of complete system collapse..
What is modularity regarding networks?
the degree to which a network is divided into smaller, densely connected groups of nodes (modules)
What is nestedness regarding networks?
a pattern where less-connected species interact with subsets of the species that more- connected species interact with, creating a hierarchical, ordered structure.
- Subsets (Untergruppen) of Interactions: If species AAA interacts with species X,Y,ZX, Y, ZX,Y,Z, and species BBB interacts with X,YX, YX,Y, the interactions of BBB (a less-connected species) are a subset of AAA's interactions.
- Hierarchical Organization: Highly connected species (generalists) interact with many other species, while less-connected species (specialists) interact only with subsets of those already interacting with generalists.
Nestedness is common in mutualistic networks (e.g., plants and their pollinators). Generalist species provide stability, and nested structures ensure that specialists can survive even if other species are lost
What is the difference between state factors and process modulators?
state factors:
long term external drivers cannot be changed by ecosystem
modulators : (physical or chemical, affect the organisms, are not consumed)
short term internal factors can be changed by ecosystem
What is the linkage density regarding networks and how do you calculate it?
average degree (number of links per node) of each node/ point
how to calculate: add all the degrees ( number of links per node) and divide it by the number of nodes e.g.: (1+2+3+1+2+1)/6= 1,
What is the main pathway of loss of phosphorus from ecosystems?
leaching and erosion , where phosphorus is washed away into water bodies, often leading to its deposition in sediments.
What is the main stock of phosphorus in ecosystems?
is found in rocks and soil minerals. In soils, phosphorus exists in both organic forms (in humus and organic material) and inorganic forms (bound to Al, Fe, Mg, Ca, etc., as precipitated phosphorus).
What is the path length regarding networks and what is the difference to network path length?
Path length : the number of steps required to connect a sequence of nodes Path is route through the nodes with the restriction that each node is allowed to be passed only once-> network path length: average number of steps along the shortest paths for all possible pairs of network nodes
What is the primary driver of carbon decomposition in ecosystems?
Microbial activity -> breaking down organic matter into simpler compounds
What is the relationship between decomposition and carbon sequestration (storage)?
While decomposition releases carbon dioxide back into the atmosphere , incomplete decomposition can lead to carbon sequestration in the soil.
What is the relationship between native diversity and invasibility of an ecosystem? What mechanisms are assumed to be underlying?
Negative Relationship (Biotic Resistance): High native diversity can block invaders because:
Resources are already used up, leaving no room for invaders. Native species may compete with or harm invaders. Resource Use: Diverse communities use resources more efficiently, limiting invaders.
Positive Relationship (Facilitation): Diverse communities can sometimes help invaders by creating favorable conditions or through disturbances.
Habitat Variety: Varied environments might offer spaces for invaders. Disturbances: Disruptions can weaken native communities, opening space for invaders.
What limits food chain length in ecosystems? (4)
energy loss (trophic efficiency) ecosystem productivity population and habitat size environmental stability
