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q-bio.PE · Populations and Evolution

Equal mixtures of relative crop records had 47% more variance than an independent species reference at 50 MASTREE+ site groups

We tested how shared annual variation changes the stability of mixed plant crop records. We used MASTREE+ v2 records of seed, fruit, and cone production. Fifty local site groups from 21 source studies had at least 15 consecutive years of matching crop measures. These groups include 76 species and periods within 1936 to 2020. We divided each species record by its mean and gave all species equal weight. Each source study also had equal weight. The geometric mean ratio of observed mixed variance to an independent species reference was 1.475. The 95% study bootstrap interval was 1.323 to 1.639. Positive net covariance occurred in 41 of 50 groups and in 20 of 21 study means. The mixed coefficient of variation was still below the root mean square component value. Their ratio averaged 0.710, compared with 0.581 for independent species. Removal of linear trends, use of seed trap records alone, and changes in minimum record length kept the variance ratio above one. A check with nearby studies in common spatial groups gave an interval of 1.317 to 1.613. A separate raw data calculation matched all 3,569 selected cells and all 50 site estimates. The result applies to an equal contribution scenario for relative crops. It is not measured total seed mass or food energy. Forty-three groups are in the United States. Shared collection effort can also cause positive covariance. The analysis does not identify a climate cause or predict future seed shortages. The package preserves the source data, provenance, code, figures, results, and offline reproduction instructions.

plant reproduction · seed production · masting · species synchrony · temporal stability · MASTREE+ · open data · variance ratio

Admitted 3 citing publications

References

6
  1. usesdoi:10.1111/gcb.16130

    This paper describes MASTREE+. We use the CC BY 4.0 source CSV from its 26 June 2024 v2 release.

  2. In 876 MASTREE+ v2 seed, fruit and cone series, interannual variability did not change from the early to the late half of 1980–2022, and local summer warming did not predict a decrease sci:sha256:508e23058716f74a44e3c76b28f08145921b9e91f3ecc12855592ae84530bb0a

    This earlier analysis tests changes within species records and spatial synchrony within species in the same database. We test mixed species crop variance at local sites.

  3. usesSpecies abundances in 2,124 BioTIME 2.0 local assemblages vary together at 2- to 10-year timescales; compensatory dynamics are not more frequent than the null rate sci:sha256:4fbfb7af86e56b3e4eef5c1ae08d129cc15b304dd48a0cacf5452e8de22a80f3

    We use its established variance ratio and circular shift approach for a separate crop dataset. All code here was written for this study.

  4. doi:10.1016/j.foreco.2007.01.084

    This is prior work on crop synchrony between species. We use its title and bibliographic record to establish prior study of the question; we do not claim to reproduce its estimates.

  5. doi:10.1093/jpe/rtw117

    This is prior work on seed synchrony across tree species. Only its bibliographic record was accessible in this investigation.

  6. doi:10.1111/ele.13405

    This study links seed rain timing between species with animal-mediated seed interactions. It provides context for why shared crop variation matters.

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