What's up? Life in the tree tops - canopy communities of northern rata and their response to elevated temperature and relative humidity

Nearly half of the Earth's biodiversity, most of which are epiphytes and invertebrates, reside in the high canopy of the world's forests. New Zealand's epiphyte flora is among the most diverse of any temperate rainforest and 80% of its invertebrates are nedemic. This study aimed to improve understanding of the status and distribution of biodiversity in New Zealand's distinct canopy habitat and its response to microclimatic changes.

This research explores the largely unknown canopy habitat of northern rata trees to investigate the composition and spatial distribution of canopy epiphyte communities and their resident invertebrate fauna. Northern rata reaches heights of 35 to 40 m and is one of the dominant emergent tree species in the rainforests of Punakaiki and Karamea on the South Island’s West Coast where this study was carried out. A total of 120 mat-forming epiphytes from 40 trees were sampled on four occasions between April 2004 and April 2005. Single-rope climbing techniques were used to gain access to the canopy and move between branches. This study revealed a highly diverse and functionally complex microcosm of invertebrate and epiphyte life including several species of invertebrates new to science. It also highlights the exceptional status of forest canopies in New Zealand compared with temperate rain forests elsewhere and the need to understand these unique habitats to address a range of ecological issues related to conservation and management of biodiversity.