Vegetation State

DISCLAIMER — Real Science, No Framework Bridge

Why no UTAC/CREP/AFET bridge: not only because the cited literature already provides the necessary quantitative structure -- a deliberate choice. This project's highly speculative AFET/UTAC experiments must never stand in the way of climate/ecology topics being accessible and usable to people who don't work inside that construct and aren't looking for renormalization groups. Real, checkable science, without the burden of an unproven framework. See PACKAGE_REGISTRY.md's "Why no UTAC/CREP/AFET bridge in the climate/ecology series" (2026-08-31) in the GenesisAeon workspace root for the full canonical note.

Status: Real, verified science + NO UTAC/CREP/AFET bridge

What this is

• Vegetation drought mortality is driven primarily by hydraulic failure:
• as soil dries and atmospheric dryness (VPD) rises, xylem water columns
• come under increasing tension until air bubbles form (cavitation),
• progressively blocking water transport.
• Choat et al. (2012, Nature 491, 752-755): 70% of 226 tree species
• from 81 sites worldwide operate with narrow (<1 MPa) hydraulic safety
• margins against injurious drought stress, largely independent of a
• site's mean annual precipitation.
• Adams et al. (2017, Nature Ecology & Evolution 1, 1285-1291): across
• assessed species, drought-induced mortality was consistently associated
• with ≥60% loss of xylem hydraulic conductivity; evidence for a
• complementary "carbon starvation" mechanism was present but not
• universal.
• Gazol et al. (2025, Nature Communications): of 940 documented global
• tree-mortality events, 96% were preceded by extreme drought (SPEI
• within the 10th percentile), with a clear trend toward longer, more
• intense droughts, especia

…

vegetation-state-utac

[](https://github.com/GenesisAeon) [](https://github.com/GenesisAeon/vegetation-state-utac/actions/workflows/ci.yml) [](https://www.python.org) [](LICENSE) [](https://doi.org/10.5281/zenodo.21780594)

GenesisAeon Package 91 — real vegetation drought-stress and hydraulic-failure mortality science. Deliberately has no UTAC/CREP/AFET bridge — see DISCLAIMER.md.

For a plain-language explanation of the same topic (German, no jargon, written for general audiences), see WHITEPAPER.md.

What's real here

• Choat et al. (2012, Nature): 70% of 226 tree species worldwide operate
• with narrow (<1 MPa) hydraulic safety margins against drought stress.
• Adams et al. (2017, Nature Ecology & Evolution): drought-induced tree
• mortality consistently associated with ≥60% loss of xylem hydraulic
• conductivity.
• Gazol et al. (2025, Nature Communications): 96% of 940 documented
• global tree-mortality events were preceded by extreme drought.
• Explicitly not framed as a single bistable tipping element — see
• DISCLAIMER.md.

Quickstart

bash pip install vegetation-state-utac

```python from vegetation_state_utac import stress_stage, StressStage

stage = stress_stage(conductivity_loss_fraction=0.65, lai_decline_fraction=0.5) assert stage == StressStage.LIKELY_MORTALITY ```

Development

bash pip install -e ".[dev]" pre-commit install ruff check src tests mypy src pytest

Citation

See CITATION.cff and .zenodo.json.