Estimating interaction strengths for diverse horizontal systems using performance data

1. Network theory allows us to understand complex systems by evaluating how their constituent elements interact with one another. Such networks are built from matrices that describe the effect of each element on all others. Quantifying the strength of these interactions from empirical data can be difficult, however, because the number of potential interactions increases non-linearly as more elements are included in the system, and not all interactions may be empirically observable when some elements are rare.
2. We present a novel modelling framework that uses measures of species performance in the presence of varying densities of their potential interaction partners to estimate the strength of pairwise interactions in diverse horizontal systems.
3. Our method allows us to directly estimate pairwise effects when they are statistically identifiable and to approximate pairwise effects when they would otherwise be statistically unidentifiable. The resulting interaction matrices can include..., This dataset comes from an annual wildflower community in Western Australia. This system is a diverse and well-studied community of annual plants which germinate, grow, set seed and die within approximately 4 months every year. Individual fecundity data were collected in 2016 when 100 50 x 50 cm plots established in the understory of West Perenjori Reserve were monitored over the length of the full field season. The resulting dataset includes between 29 to over 1,000 counts of individual plant seed production from 22 different focal species (with a median of 108 observations per species), in addition to the identity and densities of all neighbouring individuals within the interaction neighbourhood of each focal plant. Interaction neighbourhoods varied in radius from 3 to 5 cm depending on the size of the focal species. Total neighbourhood diversity was 71 wildflower species, 19 of which were recorded fewer than 10 times across the whole dataset. The species-specific effects of this latt..., Files are intended to be opened and used with R. Associated scripts and functions are available at https://github.com/malbion/JointModelFramework/.