Trophic and non-trophic seasonal interaction network for boreal forest tetrapods

Aim: Understanding the organization of the wide variety of ecological
interactions is crucial to advancing our understanding and management of
real ecosystems. We aimed to compile a “complete” network of tetrapod
trophic and non-trophic interactions for the entire North American boreal
forest biome that could be analyzed to gain insights into community
organization and function. In particular, we aimed to identify
functionally important units (modules) and species within the boreal
network, and to compare how these changed seasonally and with the
inclusion of non-trophic interactions. Location: Boreal North America Time
period: 1950 – present day Major taxa studied: Tetrapods Methods: We
compiled published ecological interactions for boreal tetrapods into a
food web (trophic interactions) and inclusive network (trophic and
non-trophic interactions). We partitioned interactions by season, creating
four networks representing the two network types per season. We examined
how the modular structure, composition of modules, assortativity of traits
within modules, and importance of different species compared across these
networks. Results: We compiled a network of 5037 ecological interactions
between 421 boreal tetrapod species. Most of these interactions (87%)
occur in summer. The summer and winter boreal food webs and inclusive
networks are modular (i.e., contain subsets of species interacting more
with each other than with species outside of the subset). Several species
attributes explain which species assort together into modules, including
physical and behavioural traits, taxonomic class, and trophic niche. A
small set of species come out as most functionally important (central,
module hubs, or responsible for the greatest network change when
non-trophic interactions are included) across all versions of the network,
and other species are important within a certain season or interaction
context. Main conclusions: Potential conservation management units
(modules) exist in the boreal forest network, and considering species’
function at the community level highlights new priorities for
species-level management.