Functional traits
We measured 22 functional traits, 19 continuous traits and three categorical traits (Table 2 ). Functional traits were measured in three healthy reproductive individuals per species. For functional traits associated to leaves we measured three mature leaves exposed to full light, using the standard protocols from the handbook for easy measurement of plant functional traits worldwide (Cornelissen et al. , 2003). Plant height (m) was measured in the field as the distance from the ground to the top of the main photosynthetic tissues. Leaf area was measured with a flatbed scanner (Hewlett Packard G3010). All weight measurements to estimate specific leaf area (SLA: total leaf area/leaf dry mass mm2 mg-1), leaf dry matter content (LDMC): leaf dry mass/leaf fresh mass mg g-1), and seed mass (mg) were obtained using a 0.01 mg precision balance (Sartorius MSE 125p). Leaf dry mass was obtained after drying samples in the oven (Lab-line Imperial V convection oven n) at 70˚C for 72 h). Leaf toughness (Fp N mm-1) was assessed with a punch test using a modified Pesola (Schindellegi Switzerland; (Kitajima and Poorter, 2010)). Leaf thickness (mm) was measured using a 0-25 mm external micrometer (Redline mechanics). For traits related to nutrient acquisition and nutritional status, leaf nitrogen concentration (LNC, mg g-1), leaf carbon concentration (LCC, mg g-1) and leaf phosphorus concentration (LPC, mg g-1), we measured one leaf per individual. The first two were determined by an elemental analyzer and the last one by colorimetric analysis in the Soil and Water laboratory at the Universidad Nacional de Colombia, Bogota.
We also classified species qualitative traits of pubescence, spinescence and dispersal syndrome. Pubescence is a very important characteristic for plants in this ecosystem because it regulates leaf temperature, increases reflectance and may act as first line of defense against herbivores (Hanley et al. , 2007; Seelmann et al. , 2007; Wang et al. , 2015) and may facilitate fog capture and slow release of water, a key trait in the functionality of the paramo as a water reservoir. We defined three categories for this trait: a non-pubescent leaf for glabrous foliar laminas, a high pubescent leaf if it had > 30% of the lamina covered with trichomes, and low pubescent leaf when < 30% of the lamina was covered with trichomes. For spinescence, we defined two categories: with and without spines. Data on the dispersal syndrome for each species was obtained from the literature or from personal observations following Pérez-Harguindeguy et al. , 2013, including anemochory (wind dispersal), endozoochory (internal animal transport), exozoochory (external animal transport), hydrochory (dispersal by water) and barochory (dispersion by gravity).
We measured the following traits related to leaf gas exchange and water balance using an open infrared gas exchange analyzer Li-Cor 6400XT (Li-Cor, Lincoln Nebraska): light-saturated photosynthetic rate (µmol CO2 m-2 s-1), leaf transpiration rate (mol H2O m-2s-1), the ratio between intercellular CO2/ambient CO2, and water use efficiency (how much water is lost for each CO2assimilated). These values were obtained on sunny mornings during the wet season, between 10:00 and 12:00 hours, setting the light intensity to 1800 µmol photons m-2 s-1, the CO2 concentration to 400µmol mol-1 and the relative humidity to 60%.
To evaluate the drought tolerance of the species we measured the leaf water potentials at pre-dawn and midday during the end of the dry season. Those values were measured following standard protocols, using a pressure chamber (PMS, Corvallis Oregon). The pre-dawn water potential, when transpiration is at its minimum, provides an indication of the water potential of the soil. Midday water potential is affected by any cuticular and stomatal transpiration and therefore broadly captures the integrated effects of plant traits and the environment on the minimum water potential a plant reaches in natural conditions (Bhaskar and Ackerly, 2006), a value known to be correlated to turgor loss point and other drought tolerance traits (Bartlett et al. , 2016). Additionally, we measured the cuticular conductance (g min) by registering the change in mass of hydrated leaves as they dried in the laboratory bench for 6-8 hours and measuring the slope after the stomata had closed, following the protocol described in Scoffoni et al. , 2018. Ambient temperature and relative humidity were measured simultaneously and fluctuated minimally during the measurements. Weight measurements were taken using a 0.01 mg precision balance (Sartorius MSE 125p). Leaf area at the beginning and at the end of the process was measured with a flatbed scanner (Hewlett Packard G3010).
Each set of traits were always measured during the same week (i.e. one week the height of all plants, one week the leaf area, etc.) or maximum in two weeks for variables that are more time consuming to get, to reduce the variation due to environmental seasonal changes on the traits. Most traits were collected during the rainy season, but on sunny clear days, except for those traits that inform us about species tolerance to drought that were taken at the end of the dry season. Seed mass data was taken whenever the species were reproducing. A detailed list of all measured traits and their probable role is listed inTable 2 .