DOI: 10.5061/dryad.s4mw6m989
title: Hurricane disturbance accelerated the thermophilization of a Jamaican montane forest

description: Thermophilization – changes in community composition towards greater
 relative abundances of species associated with warmer environments – has
 been described for plants and animals in many locations around the world.
 Disturbances of various kinds have increased rates of thermophilization in
 temperate sites, and this has been proposed, but not demonstrated, for
 some tropical environments. In this study, we tested whether disturbance
 by a Category four hurricane in 1988 (Hurricane Gilbert) increased
 thermophilization in a Jamaican montane forest by using pre- and
 post-hurricane data collected over four decades (1974–2014). We analysed
 tree species composition in permanent plots at c. 1580 m elevation in
 Jamaica’s Blue Mountains. There were 66 tree species with stem diameters
 ≥3 cm at breast height. We used published data on the altitudinal
 distribution of 62 species (94% of genetic individuals (genets)) to
 calculate the mean community altitude scores (MCAS) of the trees recorded
 in each census, as well as the MCAS of the survivors, recruits and dead
 trees after each decade. We found that thermophilization did occur (i.e.,
 MCAS decreased significantly over time), and that this was due both to a
 decreasing MCAS of recruits through the four decades (significantly lower
 than expected in the last three decades) as well as a high MCAS of trees
 that died. Thermophilization was fastest in the post-hurricane decade,
 during which time there was marked and significant increase in the MCAS of
 dead trees; this change was above and beyond expectations of long-term
 successional dynamics. The rate of compositional change equates to an
 overall decrease in MCAS of 1.6 m yr-1 over the forty-year study period.
 We conclude that this Jamaican montane forest is undergoing
 thermophilization (likely due to rising temperature) and that the
 hurricane-caused disturbance accelerated thermophilization through
 differential mortality.
description: This study was conducted using
 data from four closely-located plots (called ‘sites’ in previous papers)
 spanning a narrow altitudinal range at c. 1580 m, but differing in
 topographic position, forest structure and species composition. The four
 plots were in the Blue and John Crow Mountains National Park, Jamaica (18°
 5´N, 76° 39´W, 1543–1610 m elevation; maps in Tanner 1977, Chai et al.
 2012); the Blue Mountains have forest cover from c. 500 m to 2,256 m. Each
 study plot was 0.06 to 0.1 ha in area: Col forest (Gap forest of Tanner
 1977, 0.09 ha sampled); Wet Slope forest (0.1 ha);
 Mull
 Ridge
 forest (0.1 ha) and Mor
 Ridge forest (0.06 ha); hereafter abbreviated to Col, Slope, Mull and Mor.
 The Col, Mull and Mor plots are on the ridge top, at 1580 m, 1580 m, and
 1620 m respectively, the Slope plot is on the north side of the ridge at
 c. 1560 m. In each of
 the four plots, all stems ≥3 cm diameter at breast height (dbh) were
 measured, labelled, marked with a paint ring and identified to species in
 1974, 1984, 1994, 2004, and 2014; dead stems were located and tallied.
 Taxonomic nomenclature
 follows Adams (1972) and Proctor (1985), except where other authorities are
 listed. Stems (ramets)
 were grouped into genetic individuals (genets) for calculations of
 recruitment, mortality and thermophilization
 rates. Mean altitude values, for Jamaica, were
 calculated for 62 of the 66 tree species (94% of genets) as the midpoint
 of the species’ ranges as reported in Adams (1972), Proctor (1985), Adams (2014), and Mill (2015).
 The vast majority of the altitude data come from Adams (1972), who was
 careful to include only data based on herbarium specimens or trusted
 authorities (pers. comm.
 1974). 
 <strong>References:</strong> Adams, C. D. 1972. Flowering plants of Jamaica. - University of the West Indies, Mona, Jamaica. Adams, R. P. 2014. Junipers of the World: the genus Juniperus, 4th Edition. - Trafford Publishing. Chai, S.-L. et al. 2012. Evaluation of Forest Recovery over Time and Space Using Permanent Plots Monitored over 30 Years in a Jamaican Montane Rain Forest. - PLoS One 7: e48859. Mill, R. R. 2015. A monographic revision of the genus Podocarpus (Podocarpaceae): II. The species of the Caribbean Bioregion. – Edinb. J. Bot. 72:61–185. Proctor G. R. 1985. Ferns of Jamaica. - British Museum (Natural History), London, UK. Tanner, E. V. J. 1977. Four montane rain forests of Jamaica: a quantitative characterization of the floristics, the soils and the foliar mineral levels, and a discussion of the interrelations. -  J. Ecol.  65: 883–918.
description: For use with the R codes provided in the paper "Hurricane
 disturbance accelerated the thermophilization of a Jamaican montane
 forest", the "jadata" sheet should be first converted into
 a .csv file and loaded into R NA = missing or unknown
 values