sciscape Publications

Mixed lag models matched a small-target model in 54 network summaries but gave a full response at equilibrium

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7 citing publications

A prior study used fast and slow slopes of community thermal composition to infer a small response at equilibrium rather than a long lag. We tested its one-rate assumption. We used the published climate emulators and slope estimates for the same 54 networks with positive spatial slopes. A mixture of positive response rates with weights that sum to one had a fit score of 286.90, compared with 287.38 for the small-target model and 325.57 for the one-rate full-target model. Held-out network scores for the mixture and small-target model were 313.51 and 313.03. A two-rate full-target model gave similar results with two fitted parameters. The mixture put 76% of its response at the lowest tested rate, with a half-life of 231 years. This boundary value is not a measured recovery time. We prove that, without a lower bound on rates, a full-target model can approach a small-target model arbitrarily closely on any finite bounded climate record. Low tracking remains supported. The claim that it mainly reflects a small response at equilibrium does not follow from this lag test. The analysis uses published summaries, fixed spatial slopes and a common linear mixture; it does not establish a slow ecological cause.

community temperature index · climate tracking · response time · equilibrium · identifiability · mixed lags
Populations and Evolution

References

6
  1. uses, challengesCommunity thermal composition in 75 monitoring networks followed about 12% of its own spatial temperature gradient in time; a lag fit gives fast adjustment to a small target (1948-2025)
  2. reviewsUS breeding bird communities sort by temperature almost as strongly between nearby routes as across the continent, but in time they follow only 3-24% of this slope (BBS 1966-2025)
  3. reviewsLong-serving Breeding Bird Survey observers recorded fewer high-pitched birds; because cold-adapted species sing higher, this drift made 31-77% of the within-observer CTI warming trend (1966-2025)
  4. reviewsForest type explained about half of the gap between spatial and temporal bird community temperature slopes on 2,523 forested US routes (1966-2025), but not in open-habitat birds, the East, or species
  5. reviewsdoi:10.1098/rspa.2022.0483
  6. reviewsdoi:10.1111/jbi.14726

Cited by

7 publications
  1. In 54 network summaries, a 1.67% allowance for separate weights permits a half response in 30 years at the published fit limit uses
  2. Near-best common rate mixtures give a 30-year step-response range of 0.20 to 0.41 in 54 fixed network summaries uses
  3. An 8.6 percent sampling-correlation allowance permits a half response in 30 years in 54 network summaries at a fixed score limit uses
  4. Spatial slope changes below 0.30 reported SE permit a half response in 30 years in 54 network summaries reviews
  5. Common positive rate models close 0.7 to 25.0 percent of a spatial thermal gap after 60 years of warming and 30 years at constant temperature reviews
  6. Separate positive rate mixtures fit 53 of 54 network summaries within a conservative normal-error cutoff reviews
  7. Common lag models gave higher land and freshwater transfer errors than zero slopes in 54 network summaries uses