Snail records from the same Luquillo points had higher taxon agreement in 2017–2019 than records from different points

We tested whether recorded snail composition retained a local association from the wet season of 2017 to the wet season of 2019 at 40 fixed Luquillo forest points. We summed named counts over four visits per point and calculated taxon agreement from the resulting shares. Agreement was 0.40794 for the same point across years and 0.39194 for different points. The difference was +0.01600, or 1.60 percentage points. Two dominant taxa supplied 95.7% of the net contrast. All visit, taxon and point-group checks retained a positive difference. The primary value was below all 19 earlier two-year reference values, but this rank changed with point selection. On the same 34 points with positive counts in all 24 years, the 2017–2019 difference was +0.02483 and exceeded the 2015–2017 value of +0.01992. These finite-panel results show weak local association in the recorded species mix despite large count changes. They do not establish true population recovery or a causal storm effect. We preserve unchanged source data, provenance, all comparisons, figures, independent checks and offline code.

biodiversity · Luquillo · gastropods · species composition · repeat surveys · spatial association · disturbance