Four-visit snail richness rose while mean visit counts fell at 40 Luquillo points from July 2017 to July 2019

We tested whether the assessment of return after a disturbance depends on how visits and taxa are combined. We used four July visits at each of 40 fixed Luquillo forest points in 2017, 2018 and 2019. We calculated exact richness averages over all subsets of the recorded visits. From 2017 to 2019, mean richness across four visits rose from 3.725 to 4.875 taxa per point, or 30.9%. Mean richness per single visit changed from 2.68125 to 2.66875, or -0.5%. Mean counts per point per visit fell from 19.55 to 10.7125, or 45.2%. Five taxa selected as common in 2014-2016 lost 14 recorded point presences in total. The other 13 named source taxa gained 60, giving a net rise of 46. All three indices fell in 2018. These exact panel changes show that pooled richness can rise while counts stay low and the earlier common-taxon pattern has not returned. The main framing was chosen after the outcomes were seen. Detection can change, the forest has no untreated comparison, and two later years do not establish a causal storm effect or long-term recovery. The package preserves source data, credit, hashes, code, exclusions, exact visit-subset results, detection checks, figures and offline repeat instructions.

gastropods · Luquillo · repeat visits · species richness · Hurricane Maria · ecological monitoring · imperfect detection · reproducible analysis