VIII SOUTHERN CONNECTION CONGRESS. ABSTRACTS (1)

CLIMATE INFLUENCE ON SEED PRODUCTION AND WATER-USE EFFICIENCY (δ13C) OVER 27 YEAR IN NOTHOFAGUS OBLIQUA IN SOUTHERN CHILE 

AGUILERA-BETTI, ISABELLA1 , MUÑOZ, ARIEL1 , MURÚA, ROBERTO2 , TOLEDO-GUERRERO, ISADORA1 , JIMÉNEZ-CASTILLO, MYLTHON3 , BERRIEL, VERÓNICA4 , PERDOMO, CARLOS4 , 

1 Laboratorio de Dendrocronología y Estudios Ambientales, Instituto de Geografía, Pontificia Universidad Católica de Valparaíso.2 Departamento de Ciencias Agronómicas y Recursos Naturales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de la Frontera.3 Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile.4 Centro de Aplicaciones de Tecnología Nuclear en Agricultura Sostenible (Uruguay), Universidad de la República.

 High precipitation reductions have been observed in south central Chile during the last 50 years, however the effect of climate variability on the processes and functions of tree species is still not well understood. Utilizing 27 years of seed production records and δ13C from growth rings, we evaluated the effect of precipitation variability on seed production and water-use efficiency on Nothofagus obliqua trees in the San Martin Experimental Forest (BESM) (39° 38’ S y 73° 07’ W) in Chile. Seed production was positively correlated with precipitation during summer months of two years before the seeds fall to the forest ground. Moreover, the water-use efficiency inferred from δ13C in the growth rings of N. obliqua, was also positively correlated with the summer months during one and two years prior to the ring formation. These results suggest that precipitation reduction in this area could have a strong effect in reproductive and functional processes of N. obliqua. More information about changes in water availability and its relationship with the resources allocation in N. obliqua forests would help to estimate its responses to projected climate change scenarios for this region. 

(Sponsored by CATNAS - Centro de Aplicaciones de Tecnología Nuclear en Agricultura Sostenible (Uruguay); Universidad Austral de Chile) 

FUNCTIONAL DIVERSITY OF EPIPHYTIC LIVERWORT COMMUNITIES: PATTERNS AND DRIVERS ALONG A TROPICAL ELEVATIONAL GRADIENT

 AH-PENG, C1 , MEEK, SARAH2 , HEDDERSON, TERRY2 , WILDING, NICHOLAS2 , STRASBERG , DOMINIQUE1 , FLORES, OLIVIER1 , 1 UMR PVBMT, Faculty of Science, Human and Environment, University of La Réunion.2 Biological Sciences, University of Cape Town. 

Analysing functional traits along environmental gradients can improve our understanding of the mechanisms involved in plant community assembly. Elevational gradients as major environmental gradients provide model systems to study the factors that generate and structure biodiversity. While literature has explored community-level trait responses to environmental changes for vascular plants, functional diversity and the role of functional traits of bryophytes in ecosystem services and processes remain largely unexplored. In this study, we measured species abundance and the distribution of 12 traits related to vegetative growth of epiphytic liverworts along an elevational gradient (350-2750 m) on La Réunion island (Mascarenes). We use functional diversity indices (Villéger et al., 2008) and related them to elevation and climatic variables along the gradient. Processes implied in community assembly were investigated using both the mean and variance of trait values weighted by species abundance and compared to a null model based on species abundance randomizations. Results of this study will shed light on the drivers of community assembly of liverworts on islands and the role of this plant group in insular ecosystem processes. This work is embedded in a large- scale research program across tropical and subtropical islands (MOVECLIM) aiming at studying the different components of diversity (species richness, functional and phylogenetic diversity) to better understand the current and future distribution of bryophytes under a changing environment. 

(Sponsored by Era NetBiome Project (ANR MOVECLIM)) 

EVIDENCE OF WIDESPREAD POLLINATION-MEDIATED FACILITATION IN SOUTH ANDEAN PLANT COMMUNITIES BASED ON POLLEN TRANSFER NETWORKS 

AIZEN, MARCELO1 , TUR, CRISTINA2 , SÁEZ, AGUSTÍN3 , TRAVESET, ANNA4 , 1 Departamento de Ecología, Centro Regional Universitario Bariiloche, Universidad Nacional del Comahue - INIBIOMA.2 Institut Mediterrani d´Estudis Avançats (CSIC-UIB) IMEDEA.3 Laboratorio ECOTONO-INIBIOMA, Centro Regional Universitario Bariloche, Universidad Nacional del Comahue.4 Institut Mediterrani d´Estudis Avançats (CSICUIB) IMEDEA. 

Although plant-plant facilitation via the nurse effects seems to be common in Alpine environments, similar information for plant-plant facilitation via shared pollinators is limited. Pollinator sharing often implies interspecific pollen transfer (IPT). We studied IPT among a total of ~50 plant species distributed across three high-Andean communities at 1600, 1800 and 2000 m a.s.l. in Cerro Challhuaco (Nahuel Huapi NP) to construct networks depicting plant-plant, pollinator-mediated interactions. We analysed the relation between the (a) number of conspecific and number of heterospecific pollen grains deposited on stigmas (quantitative effect), and (b) proportion of germinated pollen and number of heterospecific pollen grains on stigmas (qualitative effect). Using GLMMs, we estimated the sign (positive, neutral or negative) of quantity and quality effects of pollinator sharing for each recipient species and each recipient-donor species pair. Communities were characterized by the presence of pollen hub-donors acting as “magnet species”. In general, facilitative and neutral pollinator-mediated interactions among plants prevailed over competition. Thus, the benefits from pollinator sharing (i.e. increased visitation and conspecific pollen deposition) seem to outweigh the costs (i.e. heterospecific deposition and conspecific pollen loss). The largest proportion of facilitated species was found in the highest elevation community, suggesting that facilitation can be even more common at lower plant densities and under unfavourable conditions for pollination. This evidence indicates that widespread facilitation in stressful environments can not only occur via increasing availability of limited abiotic resources, but also increasing attraction of scarce mutualists