DOI: 10.5061/dryad.h18931zss
title: Data from: Warming had contrasting effects on the importance of facilitative interactions with a cushion nurse species on native and non-native species in the high-Andes of central Chile

description: Alpine habitats are regarded as particularly vulnerable to the effects of
 climate change. On one hand, global warming is supposed to contributes to
 alpine environments becoming less stressful. On the other hand, altered
 snowpack due to warmer temperatures can intensify the stress in these
 habitats. The presence of non-native plants on some of these habitats is
 due to the facilitative effects exerted by native nurse plants, becoming
 an additional threat. According to the stress gradient hypothesis the
 importance of facilitative interactions with nurse species is expected to
 diminish as environmental harshness decreases due to climate change, yet
 remains important if climate change heightens the stress in alpine
 habitats. However, the responses also depend on climate change's
 impact on the nurse species. We conducted an experimental warming
 experiment in the Andes of the central Chile to assess the effects of
 warmer temperatures on the growth, reproduction and photochemical
 efficiency of the cushion nurse plant Azorella madreporica. Further we
 performed a cushion removal experiment involving three native species
 (Gamocarpha ventosa, Nocaccea magellanica and Rytidosperma pictum) and two
 non-native species (Cerastium arvense and Taraxacum officinale) to assess
 whether facilitative interactions changed with warming. We expected that
 under warmer conditions facilitation continued be important for the native
 species but decreased for the non-natives as the latter are abundant at
 warmer low elevations. We found that warmer conditions increased the
 photochemical efficiency and growth of the nurse cushions. Removal of
 cushions resulted in high mortality rates for all species. However, under
 warmer conditions, native species exhibited lower survival rates, whereas
 non-natives showed no significant changes compared to control groups. In
 summary, warmer temperatures were beneficial for the nurses maintaining
 the importance of facilitative interactions for native species, but not
 for the non-natives.
description: # Warming had contrasting effects on the importance of facilitative
 interactions with a cushion nurse species on native and non-native species
 in the high-Andes of central Chile
 ## Description of the data
 and file structure This data set contains two excel files. The first
 entitled "warming effects on cushions contains (on separate
 worksheets) all the variables measured on cushions with and without OTC.
 This file contains the following variables per worksheet: \- Biomass:
 warming (OTC/sin OTC), replicate, Rosette biomass (mg), New leaves biomass
 (mg), Brachyblast biomass (mg)\ \- Fruits: replicate, warming (OTC/sin
 OTC), number of fruits per 10 x 10 cm quadrant\ \- Fluorescence:
 replicate, warming (OTC/sin OTC), maximum photochemical efficiency,
 Electron transport rate (ETR) and non-photochemical quenching (NPQ)
 measured as indicated in the paper.\ n/a means data not available\ \-
 Photosynthesis: replicate, warming (OTC/sin OTC), respiration (Rd) and
 Photosynthesis (Pn) measured as indicated in the paper. The second file
 entitled "removal and warming" contains all data for the native
 and non-native species used to assess the effects of nurse removal with
 and without OTC (warmer conditions). This file contains the following
 variables: Species name; Species Type: native (NAT)/non-native (INV);
 Warming OTC/no warming (sin OTC); Maximum fluorescence of Chlorophyll a
 (Fv/Fm) and Photochemical efficiency of PSII (Phi) measured as indicated
 in the method section of the paper; biomass and standardized biomass
 (stdbiomass) of survivors in the experimental setup indicated in the
 paper.