mixed-forest-resilience-utac

GenesisAeon Package 113 — why structurally diverse forests outperform monocultures. Extracted from an independent assessment of a German nature-conservation policy report — its forest-conversion (Waldumbau) section was the one part worth pursuing as durable science, separate from the funding-program/legal-framework content in the rest of that document (deliberately not built, same precedent as mountain- governance-adaptation-utac (P104) and landscape-restoration- hydrology-utac/urban-green-infrastructure-utac (P107/P108)). 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.

Deliberately not one-sided

This package includes a real complication, not just confirmation: is_beech_immune_to_drought_mortality() returns False — European beech, the tree species most often promoted as spruce's resilient alternative, still died at a real, measured rate (~7%) in the same 2018–2019 drought that killed ~50% of sampled spruce. Mixed-forest resilience is a large, real reduction in risk — not immunity.

What's real here

• Pretzsch & Schütze (2009, European Journal of Forest Research) — 37 real experimental plots across Central Europe (age 37–155 years): mixed Norway spruce/European beech stands produce up to 59% more aboveground biomass than neighboring pure stands — but this is site-dependent, ranging from −46% to +138%, not a universal constant.
• Jactel & Brockerhoff (2007, Ecology Letters) — a real, worldwide meta-analysis of 119 studies: tree diversity reduces insect herbivory via "associational resistance" — strong and consistent for host-specialist insects, more variable for generalists.
• Jactel, Scherer-Lorenzen et al. (2025, Journal of Pest Science) — real field evidence from Germany's MyDiv tree- diversity experiment (established 2003): bark beetle (Ips typographus) damage decreased significantly as the proportion of spruce in mixed plots decreased — directly relevant to Germany's real, ongoing spruce-monoculture dieback crisis.
• Bosela et al. (2025, Forest Ecology and Management) — a real 24-year paired field comparison in Slovakia (70-year-old spruce monoculture vs. 150-year-old mixed forest, identical soils): the 2022 drought significantly reduced growth and soil CO₂ efflux in the monoculture, while the mixed forest stayed stable.
• Obladen et al. (2021, Agricultural and Forest Meteorology) — the honesty-check citation: real field sampling in Bavaria (186 spruce, 143 beech trees) found ~50% spruce mortality but also ~7% beech mortality in the 2018–2019 drought.

Quickstart

pip install mixed-forest-resilience-utac

from mixed_forest_resilience_utac import (
    SPRUCE_BEECH_OVERYIELDING, is_overyielding_universal,
    meta_analysis_study_count, is_effect_uniform_across_insect_types,
    MYDIV_BARK_BEETLE_EVIDENCE, is_modeled_not_measured,
    SLOVAKIA_PAIRED_COMPARISON, stands_share_identical_soil_conditions,
    BAVARIA_2018_2019_MORTALITY, is_beech_immune_to_drought_mortality,
    mortality_reduction_factor,
)

print(SPRUCE_BEECH_OVERYIELDING.max_overyielding_pct)  # 59.0
print(is_overyielding_universal())                     # False
print(meta_analysis_study_count())                     # 119
print(MYDIV_BARK_BEETLE_EVIDENCE.experiment_established_year)  # 2003
print(SLOVAKIA_PAIRED_COMPARISON.study_duration_years)  # 24
print(BAVARIA_2018_2019_MORTALITY.beech_mortality_pct)  # 7.0
print(is_beech_immune_to_drought_mortality())           # False
print(mortality_reduction_factor())                     # ~7.14

Development

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

Citation

See CITATION.cff and .zenodo.json.