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Wood in the deep sea serves as a substantial food source in an otherwise barren environment, forming specialized, endemic, and diverse community assemblages. This biodiversity reliance on a terrestrial source creates a linkage by which anthropogenic impacts on land can alter the deep oceans. Knowledge of the alpha‐ or beta‐diversity of entire wood‐fall communities, and wooden drivers of each would elucidate the terrestrial and deep‐sea linkage. We report on a multifactorial experiment in the deep ocean in which alpha‐ and beta‐diversity of 43 wood falls and 11 tree species are quantified over time, wood density, and wood size. We tested multiple hypotheses seeking to link how biodiversity on land may impact the biodiversity in the deep oceans. A tremendous biodiversity occurred among these wood falls in the deep Gulf of Mexico; 114 invertebrate species from 10 phyla. Time, wood hardness, and wood size all impacted various components of community structure. In many cases, these effects were additive. Species occurring on softwoods versus hardwoods and small versus large wood falls were compositionally different. Although various processes can control community structure, this experiment suggests a strong influence of environmental filtering and host specificity of wood‐fall invertebrates suggesting an intimate coupling to tree biodiversity and biomass on land. [ABSTRACT FROM AUTHOR]

A multitude of hypotheses have been invoked to explain increases in richness with increases in energy availability. Experiments have the potential to reveal causality, and species–energy experiments have yielded substantial insights into energetic community assembly. Here, we examine six mechanisms underlying species–energy relationships in an experimental wood fall system in the deep Gulf of Mexico. Twenty‐four wood falls were deployed in the deep Gulf of Mexico for 21 months. To test for differences in total energy availability, individual wood falls ranged in size from 0.91 to 24 kg, corresponding to different levels of energy available to the wood‐obligate invertebrate communities assembling on wood falls. To test for differences in total energy accessibility, we chose a softwood (pine, n = 12) and soft hardwood (sugarberry, n = 12). Structural equation models were used to disentangle the multiple hypothesized pathways by which changes in wood fall type and mass correlated with richness. Whereas we find support for the more individuals hypothesis, we also find that niche dynamics and competition play important roles as well linking energy and diversity. Furthermore, we find that not only the total energy but also the accessibility of that energy, dictating rates of energy flow, leads to differences in community structure. Using structural equation modeling (SEM), we evaluate seven hypotheses to demonstrate that no single hypotheses alone can predict the species–energy relationship. [ABSTRACT FROM AUTHOR]