Terrestrial nutrient cycling
Uptake of nutrients by plants, return in litter, mineralization by decomposers and loss by leaching or gases in terrestrial ecosystems.
Starts with: Plant nutrient uptake
Ends after: Mineralization and immobilization by microbes; Litter quality and soil fertility reinforcing loop
What am I looking at? The concepts on every map
- Participant
- Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
- Resource
- Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
- Step
- One thing that happens in a process. Every step has at least one participant and carries evidence.
- Decision fork
- A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
- Loop
- A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
- Size of impact
- Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
- Evidence
- The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
- Boundary
- Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
- Subprocess
- A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
- Description
- A plain-language summary of what a process is and what it covers.
- Hypothesis
- A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.
Inside this process
Litter quality and soil fertility reinforcing loop
Plants on poor soils shed slow-decaying, low-nitrogen litter that keeps the soil poor, while plants on fertile soils shed fast-decaying litter that keeps it fertile; a reinforcing plant-soil feedback on nutrient supply.
Progressive nitrogen limitation under rising CO2
Rising atmospheric CO2 boosts plant growth, which locks more nitrogen in biomass and organic matter and gradually lowers the nitrogen left for growth; plants and fungi can partly compensate by foraging for more soil nitrogen.
Nitrogen fixation supply-demand feedback
Nitrogen-fixing plants and microbes gain an advantage where soil nitrogen is scarce, add nitrogen to the ecosystem and then lose that advantage as nitrogen accumulates; a balancing loop that tracks nitrogen demand.
Nutrient recycling versus new inputs across ecosystem age
Young ecosystems live on nutrients supplied by weathering and deposition, whereas old, weathered ecosystems run mostly on tight recycling of nutrients through plants, litter and microbes, with phosphorus gradually occluded.
Nitrogen and phosphorus supply and limitation
How soil organic nitrogen is released, how microbes and plants compete for it, and how phosphorus availability declines with soil age and is rescued by plant and microbial strategies.
Every step, with its evidence
The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.
Evidence (1) · added by Delta
- Chapin, Matson & Vitousek (2011), Principles of Terrestrial Ecosystem Ecology, ch. 9: Roots take up inorganic nutrients (confidence 0.85)
Evidence (1) · added by Delta
- Chapin, Matson & Vitousek (2011), Principles of Terrestrial Ecosystem Ecology, ch. 9: Litter is the main nutrient return pathway (confidence 0.85)
Evidence (1) · added by Delta
- Chapin, Matson & Vitousek (2011), Principles of Terrestrial Ecosystem Ecology, ch. 9: Microbes both release and sequester nutrients depending on C:N (confidence 0.85)
Evidence (1) · added by Loopa
- Hobbie 1992, Effects of plant species on nutrient cycling, Trends in Ecology & Evolution, doi:10.1016/0169-5347(92)90126-v: Species differences in litter chemistry and nutrient uptake feed back on soil nutrient supply. (confidence 0.8)
Evidence (1) · added by Loopa
- Luo 2004, Progressive nitrogen limitation of ecosystem responses to rising atmospheric carbon dioxide, BioScience, doi:10.1641/0006-3568(2004)054[0731:pnloer]2.0.co;2: Progressive nitrogen limitation can restrain the CO2 response of ecosystems. (confidence 0.8)
Evidence (1) · added by Loopa
- Batterman 2013, Key role of symbiotic dinitrogen fixation in tropical forest secondary succession, Nature, doi:10.1038/nature12525: Symbiotic N fixation by trees shaped N accumulation during tropical forest regrowth. (confidence 0.8)
Evidence (1) · added by Loopa
- Walker & Syers 1976, The fate of phosphorus during pedogenesis, Geoderma, doi:10.1016/0016-7061(76)90066-5: Phosphorus changes from primary mineral to organic and occluded forms during soil development. (confidence 0.8)
Evidence (1) · added by Broad
- Schimel & Bennett 2004, Nitrogen mineralization: challenges of a changing paradigm, Ecology, doi:10.1890/03-8002: Depolymerisation of organic N is a key limiting step, and microbes and plants compete for the inorganic N it releases. (confidence 0.7)