Assembly history dictates ecosystem functioning: evidence from wood decomposer communities.

Community assembly history is increasingly recognized as a fundamental determinant of community structure. However, little is known as to how assembly history may affect ecosystem functioning via its effect on community structure. Using wood-decaying fungi as a model system, we provide experimental evidence that large differences in ecosystem functioning can be caused by small differences in species immigration history during community assembly. Direct manipulation of early immigration history resulted in three-fold differences in fungal species richness and composition and, as a consequence, differences of the same magnitude in the rate of decomposition and carbon release from wood. These effects - which were attributable to the history-dependent outcome of competitive and facilitative interactions - were significant across a range of nitrogen availabilities observed in natural forests. Our results highlight the importance of considering assembly history in explaining ecosystem functioning.

Diversity and distribution of fungal foliar endophytes in New Zealand Podocarpaceae.

The diversity and distribution of fungal endophytes in the leaves of four podocarps (Dacrydium cupressinum, Prumnopitys ferruginea, Dacrycarpus dacrydioides, and Podocarpus totara, all Podocarpaceae) and an angiosperm (Kunzea ericoides, Myrtaceae) occurring in close stands were studied. The effects of host species, locality, and season on endophyte assemblages were investigated. Host species was the major factor shaping endophyte assemblages. The spatial separation of sites and seasonal differences played significant but lesser roles. The mycobiota of each host species included both generalist and largely host-specialised fungi. The host-specialists were often observed at low frequencies on some of the other hosts. There was no clear evidence for family-level specialisation across the Podocarpaceae. Of the 17 species found at similar frequencies on several of the podocarp species, 15 were found also on Kunzea. Many of the endophytes isolated appear to represent species of fungi not previously recognised from New Zealand.

Diversity and distribution of saprobic microfungi in leaf litter of an Australian tropical rainforest.

The diversity and distribution of microfungal assemblages in leaf litter of a tropical Australian forest was assessed using two methods: (1) cultures were isolated using a particle filtration protocol (wet season 2001), and (2) fruit bodies were observed directly on leaf surfaces following incubation in humid chambers (wet and dry season of 2002). Four tree species were studied using both methods, namely Cryptocarya mackinnoniana (Lauraceae), Elaeocarpus angustifolius (Elaeocarpaceae), Ficus pleurocarpa (Moraceae), and Opisthiolepis heterophylla (Proteaceae). An additional two species, Darlingia ferruginea (Proteaceae) and Ficus destruens (Moraceae), were studied using direct observations. In total, fruiting bodies of 185 microfungal species were recorded on leaf surfaces (31-81 species per tree species), and 419 morphotypes were detected among isolates obtained by particle filtration (111-203 morphotypes per tree species). Although the observed microfungal diversity was higher with the particle filtration protocol, both methods concurred with respect to microfungal distributions. The overlap of microfungal species in pair wise comparisons of tree species was low (14-30%), and only 2 and 3% of microfungal species were observed in leaves of all tree species by particle filtration and by direct observations respectively. Multivariate analysis of data from direct observations confirmed the hypothesis that microfungal assemblages are strongly influenced by host phylogeny and are also affected by seasonal and site factors. The importance of host species in shaping microfungal distributions was also supported by the particle filtration data. Several taxa new to science, as well as some widespread saprotrophs, were detected on only one host. The underlying reasons for this affinity remain unclear, but we hypothesise that a number of factors may be involved such as fungal adaptation to plant secondary metabolites or the presence of a biotrophic phase in the fungus' life cycle.