Late Quaternary evolution of the dryland ecosystem, Central Otago, New Zealand.
Pre-settlement paleoecology of Central Otago's semi-arid lowlands
Due to Central Otago’s distance from the ocean, and the fact that it is in the rainshadow of the Southern Alps, the region is a place of climatic extremes. It is the driest region of NZ (167mm precipitation in Alexandra, 1963-64), consistently records the coldest winter temperatures (-21.6°C in Ophir, 3 July 1995), and some of New Zealand’s highest summer temperatures.
Much of Central Otago has been highly modified by burning and grazing. The original vegetation communities and associated fauna have largely vanished, with introduced grasses, and weeds such as sweet briar (Rosa rubiginosa) and hawkweed (Hieracium spp.) now common throughout. The character and composition of the lost biota associated with Central Otago’s distinctive semi-arid lowland ecosystems remains an ecological puzzle. Paleoecological reconstructions for Central Otago are largely based on pollen records from high elevation bogs. So far, only 2 pollen records have been published for sites below 550m altitude in Central Otago, Earnscleugh Cave (Clark et al. 1996) and Ida Valley (McGlone & Moar 1996).
During this study, several rockshelters with late Holocene sediments containing well-preserved plant macrofossils (seeds, wood and leaves) were discovered. These plant macrofossils provide a glimpse of the vegetation as it existed prior to the arrival of humans. Several plant species represented in these deposits no longer exist in Central Otago, while others that are now widespread were rare prior to human settlement. Animal bones and feathers preserved in these dry rockshelter sites provide evidence of the faunal associations with vegetation.
Avian herbivory in dryland ecosystems
Significant deposits of coprolites were discovered in dry rockshelter sediments during this study. These provide an unprecedented resource for studying the diet of extinct birds, niche partitioning in moa, and the effects of avian herbivory on the composition and structure of dryland vegetation communities. Macrofossil analyses combined with ancient DNA analyses (carried out during a visit to the Australian Centre for Ancient DNA) have identified the diets of at least three moa species from a range of different habitats, and provided the first evidence of lost mutualistic relationships between extinct avian herbivores and certain New Zealand plant species.
Rockshelter overlooking the Clutha River.
Moa coprolites from a Central Otago rockshelter
Example of 600-3,000 year old desiccated plant remains excavated from a Central Otago rockshelter deposit in May 2005. Scale is 3cm
- Wood, J.R., Rawlence, N., Cooper, A. 2007a. Interspecific and habitat-related intraspecific variation in the diet of late Holocene moa (Aves: Dinornithiformes) from South Island, New Zealand.5th International Southern Connection Conference, Adelaide, South Australia. p.78.
- Wood, J.R., Rawlence, N., Cooper, A. 2007b. Coprolites shed new light on the diet of late Holocene moa from southern New Zealand.CAVEPS, Melbourne, Australia.
- Lee, W.G.,Wood, J.R. 2007. Avian function in New Zealand terrestrial ecosystems the impact of extinctions, population declines and new introductions.5th International Southern Connection Conference, Adelaide, South Australia. p.44.
- Rogers, G.,Wood, J.R. 2007a. Clipping and freeze-drying in rainshadow New Zealand: how birds and climate shaped plant phenotypes and community structure.International Association of Vegetation Science Conference, Palmerston North.
- Rogers, G.,Wood, J.R. 2007b. Grazing and browsing in godzone: avian herbivory in the evolution of New Zealand's dryland plants.New Zealand Ecological Restoration Network Conference, Christchurch.
- Wood, J.R. 2006a. Diet of moa at Daley's Flat, Dart River Valley, western Otago: preliminary results from a study of coprolites.Joint conference of the New Zealand Ecological Society and the Ecological Society of Australia, Wellington. p.172.
- Wood, J.R. 2006b. In the heart of a New Zealand desert: Reconstructing the late Holocene, semi-arid ecosystem of the Cromwell Gorge, Central Otago, South Island, New Zealand.Joint conference of the New Zealand Ecological Society and the Ecological Society of Australia, Wellington. p.172.
- Wood, J.R. 2005a. Taphonomy of a Holocene moa swamp deposit, Styx Valley, Central Otago. In: Pettinga, J.R., Wandres, A.M. (eds.).New Zealand Geological Society 50th Annual Conference, Kaikoura. Geological Society of New Zealand Miscellaneous Publication 119a: p.96.
- Wood, J.R. 2005b. Some aspects on the feeding ecology of moa in the late Holocene dryland basins of Central Otago, New Zealand.Joint conference of the New Zealand Freshwater Sciences Society and New Zealand Ecological Society, Nelson.
- Wood, J.R., Read, S.E. 2005. Anaglyphs as a tool for viewing taphonomy: an example from a Holocene moa fen deposit, Styx Valley, Central Otago. In: Pettinga, J.R., Wandres, A.M. (eds.). New Zealand Geological Society 50th Annual Conference, Kaikoura. Geological Society of New Zealand Miscellaneous Publication 119a: p.96.
- Wood, J.R. 2004. Reconstructing Holocene ecosystems at Mason Bay, Stewart Island.New Zealand Ecological Society Conference, Invercargill. p.61.
- Wood, J.R. 2003. Late Quaternary geology, biota and climate of Mason Bay, Stewart Island. In: Mortimer, N., Lee, D. (eds.).Geological Society of New Zealand 2003 Annual Conference, Dunedin. Geological Society of New Zealand Miscellaneous Publication 116a: p.209.
- Wood, J. 2003. Quaternary geology, biota and climate at Mason Bay, Stewart Island, New Zealand. Unpubl. BSc Hons. Dissertation, University of Otago, Dunedin, New Zealand. 89p.
- Wood, J.R. in press. Moa gizzard content samples from Scaife’s Lagoon, northwest Otago, Styx swamp, Central Otago and Cheviot swamp, north Canterbury.Records of the Canterbury Museum 21.
- Lee, D., Kennedy, L., Bannister, J.,Wood, J. in press. Paleogardens New Zealand’s fossil plants. In:New Zealand Geosciences in the 21st Century.
- Wood, J.R. 2006. Subfossil kakapo (Strigops habroptilus) remains from near Gibraltar Rock, Cromwell Gorge, Central Otago, New Zealand.Notornis 53(1): 191-193.
- Wood, J.R. 2005. Food for thought: Revisiting the topic of moa feeding ecology.New Zealand Ecological Society Newsletter 11:5-6.
- Wood, J.R. 2003. Annual and monthly patterns in recoveries of beach-wrecked Procellariiformes from Southland, New Zealand 1990-2000.Notornis 51(2): 103-112.
- Wood, J. 1998. The effects of an abnormally cold winter spell on Southland birds.Notornis 45: 126-128.