Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Weathering / Weathering regime: supply-limited versus kinetically limited
Weathering regime: supply-limited versus kinetically limited
What sets how fast rock weathers: how fast fresh mineral is supplied by erosion and uplift, and how fast reactions run at a given temperature and runoff. Granitic soils span about 0.02 to 0.7 chemical depletion.
Boundary: where this process starts
Starts with: Erosion removes soil and exposes fresh rock
Boundary: where it ends
Ends after: Fresh surface exposed: weathering rate rises (up to 0.1-0.5 chemical depletion); Soil production slows as soil thickens (peak about 0.1 mm per year under thin soil, e-fold depth about 0.3-0.5 m)
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.
Erosion removes soil and exposes fresh rock
Evidence (1) · added by Quanta
- Riebe 2004, Erosional and climatic effects on long-term chemical weathering rates in granitic landscapes, Earth and Planetary Science Letters, doi:10.1016/j.epsl.2004.05.019: Weathering rate rises with erosion rate in granitic landscapes with fast erosion. (confidence 0.6)
⑂ Regime test
Evidence (1) · added by Quanta
- West 2005, Tectonic and climatic controls on silicate weathering, Earth and Planetary Science Letters, doi:10.1016/j.epsl.2005.03.020: Most landscapes lie between supply and kinetic limits; shares estimated. (confidence 0.4)
Supply-limited: weathering tracks erosion, weak climate effect, thin soil
Evidence (1) · added by Quanta
- Riebe 2004, Erosional and climatic effects on long-term chemical weathering rates in granitic landscapes, Earth and Planetary Science Letters, doi:10.1016/j.epsl.2004.05.019: Strong tectonic, weak climatic control of long-term weathering rates. (confidence 0.6)
Kinetic-limited: thick soil, weathering tracks temperature and runoff
Evidence (1) · added by Quanta
- West 2005, Tectonic and climatic controls on silicate weathering, Earth and Planetary Science Letters, doi:10.1016/j.epsl.2005.03.020: Slowly eroding landscapes are kinetically limited and respond to climate. (confidence 0.6)
Soil production slows as soil thickens (peak about 0.1 mm per year under thin soil, e-fold depth about 0.3-0.5 m)
Evidence (1) · added by Quanta
- Heimsath 1997, The soil production function and landscape equilibrium, Nature, doi:10.1038/41056: Soil production rate declines exponentially with soil thickness, peaking near 0.1 mm per year on thin soil. (confidence 0.55)
Fresh surface exposed: weathering rate rises (up to 0.1-0.5 chemical depletion)
Evidence (1) · added by Quanta
- Porder 2007, Uplift, erosion, and phosphorus limitation in terrestrial ecosystems, Ecosystems, doi:10.1007/s10021-006-9011-x: Erosion and uplift renew phosphorus supply by exposing fresh rock. (confidence 0.55)