## Date: June 12, 2023

## Dataset Title: Relative growth rate data elevational gradient Puerto Rico

## Dataset creators: Maria Natalia Umaña, Nathan G. Swenson, Gabriel Arellano

## Dataset contact: maumana@umich.edu

## Funding: NSF DEB-1501341

## Key points: 
-Trees display a dynamic functional response to extreme climatic events, with leaf traits related to efficient photosynthesis driving tree growth after hurricanes with, while after the drought, tree growth increased for trees with hydraulically efficient traits (low wood density and water use efficiency). 

-In the longer term, over both drought and hurricanes, tree size was the only predictor of growth, with growth increasing with smaller trees. However, the predictive power of traits was low, suggesting that the devastating effects of these extreme events may weaken the effect of traits on growth. 

##Research overview:
Identifying the functional traits that enable recovery after extreme events is necessary for assessing forest persistence and functioning, yet this is a difficult task because the traits mediating the responses to disturbance may vary depending on the disturbance type and over time. This study investigates the effects of traits on tree growth ­–for short and longer terms– in response to two vastly different extreme climatic events, droughts, and hurricanes, in a Puerto Rican forest. 

## Methodology: Relative growth rate (RGR) was calculated for all trees by using the following the equation:using change in diameter at breast height of the focal tree, over different time periods. RGR was calculated at two temporal scales, short and long periods. For the short periods, I used a single census interval, either 2016-2017 or 2017-2018 For the longer period, I used the period from 2016 to 2019.  

## Description of the data and file structure:

plot: refers to the elevation in m, ranges from 250 to 1000.
tag: tree unique identification code
SP.CODE: species name. Cecropia schreberiana, Cordia borinquensis,  Dacryodes excelsa, Henriettea squamulosa, Micropholis garciniifolia, Sloanea berteroana.
rgr17: tree relative growth rate during 2016-2017 (mm mm-1 year-1). Obtained from dendrometer data.
rgr18: tree relative growth rate during 2017-2018 (mm mm-1 year-1). Obtained from dendrometer data.
rgr.long: tree relative growth rate during 2016-2019 (mm mm-1 year-1). Obtained from dendrometer data.

Related publication:
Umaña, M. N. In review. The interplay of drought and hurricanes on tree recovery: insights from dynamic and weak functional responses. Forthcoming