Evaluating sampling completeness in a desert plant-pollinator network

CHACOFF, NATACHA; VÁZQUEZ, DP,; LOMASCOLO, SILVIA; STEVANI, EL; DORADO, JIMENA; PADRÓN, BENIGNO

JOURNAL OF ANIMAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2012 vol. 81 p. 190 - 200

0021-8790

The study of plant-pollinator interactions in a network context is receiving increasing attention. This approach has helped to identify several emerging network patterns such as nestedness and modularity. However, most studies are based only on qualitative information, and some ecosystems, such as deserts and tropical forests, are underrepresented in these data sets. We present an exhaustive analysis of the structure of a four-year plant-pollinator network from the Monte desert in Argentina using qualitative and quantitative tools. We describe the structure of this network and evaluate sampling completeness using asymptotic species richness estimators. Our goal is to assess the extent to which the realised sampling eort allows for an accurate description of species interactions and to estimate the minimum number of additional censuses required to detect 90% of the interactions. We evaluated completeness of detection of the community-wide pollinator fauna, of the pollinator fauna associated to each plant species and of the plant-pollinator interactions. We also evaluated whether sampling completeness was infuenced by plant characteristics, such as ower abundance, ower life span, number of interspecic links (degree) and selectiveness in the identity of their ower visitors, as well as sampling effort. We found that this desert plantpollinator network has a nested structure and that it exhibits modularity and high network-level generalisation. In spite of our high sampling effort, and although we sampled 80% of the pollinator fauna, we recorded only 55% of the interactions. Furthermore, although a 64% increase in sampling eort would suce to detect 90% of the pollinator species, a 5-fold increase in sampling eort would be necessary to detect 90% of the interactions. Detection of interactions was incomplete for most plant species, particularly specialists with a long owering season and high ower abundance, or generalists with short owering span and scant owers. Our results suggests that sampling of a network with the same eort for all plant species is inadequate to sample interactions. Sampling the diversity of interactions is labor intensive, and most plantpollinator networks published to date are likely to be undersampled. Our analysis allowed estimating the completeness of our sampling, the additional effort needed to detect most interactions and the plant traits that influence the detection of their interactions.