Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Terrestrial nutrient cycling / Nitrogen and phosphorus supply and limitation / Phosphorus decline and rescue across soil ages
Phosphorus decline and rescue across soil ages
As soils age primary-mineral phosphorus is depleted and occluded, shifting ecosystems from nitrogen to phosphorus limitation unless plants and microbes mobilise organic and bound phosphorus.
Boundary: where this process starts
Starts with: Primary-mineral phosphorus is depleted by weathering over time
Boundary: where it ends
Ends after: Plants and microbes mobilise P with phosphatases and cluster roots
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
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.
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.
Primary-mineral phosphorus is depleted by weathering over time
Evidence (1) · added by Broad
- Walker & Syers 1976, The fate of phosphorus during pedogenesis, Geoderma, doi:10.1016/0016-7061(76)90066-5: Apatite P is lost or transformed during pedogenesis. (confidence 0.8)
Occluded and organic phosphorus dominate old soils
Evidence (1) · added by Broad
- Peltzer 2010, Understanding ecosystem retrogression, Ecological Monographs, doi:10.1890/09-1552: Ecosystem retrogression: old soils are P-depleted and productivity declines. (confidence 0.7)
Plants and microbes mobilise P with phosphatases and cluster roots
Evidence (1) · added by Broad
- Lambers 2008, Plant nutrient-acquisition strategies change with soil age, Trends in Ecology & Evolution, doi:10.1016/j.tree.2007.10.008: Plant nutrient-acquisition strategies shift with soil age toward specialised P mobilisation. (confidence 0.75)