DOI: 10.5061/dryad.tm5sv
title: Data from: Competition and facilitation determine dwarf mistletoe infection dynamics

description: 1. Interspecific interactions have a fundamental role in plant population
 dynamics, as they may set the conditions for species coexistence.
 Parasitic plants, like dwarf mistletoes, offer the opportunity to study
 competition for resources that are different from those consumed by most
 plants, allowing for a better understanding of the interaction. 2. We
 explored how interspecific interactions between two dwarf mistletoe
 species (Arceuthobium), co-infecting the same host species (even sharing
 the same individual tree of Pinus hartwegii) affect their infection
 dynamics at two different stages of population development (colonization
 of new hosts and subsequent growth), and if heterogeneity in resource
 availability (host density and size structure) affects these interactions.
 For that purpose, we integrated these processes into a spatially-explicit
 model of density-dependent population growth. 3. We found that
 self-regulation (density-dependence) was strong for both species; however
 the intensity and sign of interspecific interactions changed depending on
 host size and demographic process. Population growth in A. globosum was
 reduced by competition, except for smaller hosts where A. globosum growth
 was facilitated by A. vaginatum. A. vaginatum was facilitated by A.
 globosum regardless of host size. Colonization of new hosts by A. globosum
 was enhanced by previous infection by the other species, showing
 intraguild facilitation. 4. Demographic importance of interactions
 depended on stand structure: in homogeneous, low-density forests,
 facilitation predominates, increasing the population sizes of both
 species, whereas the opposite occurs in heterogeneous and dense forests.
 Both species achieved stable coexistence, fulfilling the invasibility
 criterion because each mistletoe species can invade a forest that is
 already infected by the other species. 5. Synthesis. Despite the
 fundamentally different mechanisms underlying the interactions between
 mistletoes compared with non-parasitic plants, our results reveal that
 their behaviour at the population level is similar. Stabilizing
 mechanisms, like strong self-limiting population growth, allow dwarf
 mistletoe coexistence. Interactions shift as populations develop, and they
 depend largely on environmental factors such as forest structure.
 Intraguild mutualism is shown as a relevant process for colonization of
 new spaces, highlighting the complexity of competitive/facilitative
 interactions between parasitic plants, a formerly unexplored subject.
 Interactions can only be fully understood when integrating all their
 components at the population level. Analysing these interactions may
 contribute to the understanding of plant-plant interactions in general,
 and convey interesting implications for forest management.
description: Dwarf mistletoe
 ratingsData collected in the
 field from November 2008 (t1) to May 2011 (t6) for dwarf mistletoe
 interaction modelling. Tree refers to the host tree, dbh to diameter to
 breast height, MDMR to modified dwarf mistletoe rating, t to time, and t+1
 to time +1.Data base_Competition and
 facilitation between dwarf
 mistletoes.xlsxPolar coordinates and
 distances between treesData of the polar
 coordinates of the host trees (x,y), where tree no. 3 is the center.
 Distances between all trees are computed.Polar coordinates and
 distances.xlsx