Marcescence and prostrate growth in tree ferns are adaptations to cold tolerance

Cold tolerance strategies in plants vary from structural to biochemical. Many temperate tree fern taxa are marcescent—retaining whorls of dead fronds encircling the upper trunk—or develop short or prostrate trunks possibly to insulate against cold temperatures that might detrimentally affect their trunks and growing crowns. We asked the following questions: (1) do global growth patterns traits of temperate taxa relate to environmental factors associated with latitude (a proxy for seasonality and frost tolerance) and elevation (a proxy for temperature), (2) do growth patterns of tree ferns in New Zealand vary along a temperature related gradient, and (3) do marcescent tree fern skirts insulate the growing crown from sub-zero temperatures? We review the global and regional distributions of these structural and morphological traits within Cyatheales. Further, we assess the patterns of tree fern marcescence, and other traits potentially associated with cold tolerance (no trunk, prostrate, s..., Global distribution of growth forms
We reviewed the descriptive literature on tree ferns to identify, where possible (skirts are not a frequently described trait), the global proportion and distribution of tree ferns with marcescent skirts and/or prostrate taxa. We conducted a literature search using the Google Scholar (https://scholar.google.com), Scopus (www.scopus.com) and ISI Web of Science (www.isiknowledge.com) databases with the search terms [“tree fern” OR “tree-fern” OR \"treefern\"] and [“skirt*” OR “collar” OR “marcescen* OR “attached necromass” OR “prostrate”]. To identify taxa from America we also used Google Scholar to search in Spanish and Portuguese using [\"helecho* aborescente”, OR “helecho* arbóreos” AND “falda”] and [“samabaia” AND “saia”]. Finally we checked for the presence of skirts as a recorded trait in the Botanical Information and Ecology Network (BIEN; https://bien.nceas.ucsb.edu/bien/biendata/) database.
The geographic distribution and elevation data of all ext..., , # Marcescence and prostrate growth in tree ferns are adaptations to cold tolerance

[https://doi.org/10.5061/dryad.tx95x6b7f](https://doi.org/10.5061/dryad.tx95x6b7f)

## Description of the data and file structure

The treefern_skirts.zip file contains an RStudio project with all the data and code required to reproduce our analyses. Open the treefern_skirts.rproj file and ensure that you have the required packages/versions.

### Files and variables

#### File: treefern\_skirts.zip

**Description:** 

The .`/data/` folder contains all data for the project.

The `./data/global.csv` contains the dataset put together for the global review of treefern growth forms, alongside `temp.csv` which has all of the GBIF records of treefern occurrences globally. We could not supply these data, as they are protected by CC, and so requires direct download from GBIF. Initially, we reviewed the descriptive literature on tree ferns to identify, where possible (skirts are not a frequently described trait),...