IAWA publishes four issues of its journal every year, containing papers on all aspects of wood anatomy. Periodically, a symposium or group of papers addresses a particular subject, and in addition to including these papers in the journal, they are published as a special issue made available to a broader audience. This is the fourth special issue on tree-ring research, the previous ones being on ‘Growth rings in tropical trees’ (1989), ‘Growth periodicity in tropical trees’ (1995) and ‘Dendrochronology in Monsoon Asia’ (1999).
This volume contains nine papers which were presented at the first Asian Dendrochronological Conference in Bangkok in September 2007. The title does imply a wider coverage than the contents, and I anticipated more information on tropical taxa, which are admittedly more difficult to study because their growth rings are often less easy to recognise, interpret and correlate with climate. The papers in this volume cover studies in India (one paper), China (six papers), Japan (one paper) and South Korea (one paper). Most relate to conifer species (softwoods) rather than angiosperm trees (hardwoods), and apart from the first paper, none of the species studied or mentioned are tropical, despite the tropical location of the meeting. Since the papers are all quite different I will comment on each one's content in turn.
The first paper by Bhattacharyya & Shah is a review of tree ring research in India, concentrating on the Himalaya, Peninsular India and Tertiary fossil woods. Various species of Himalayan Abies, Cedrus, Picea, Pinus, Larix, Taxus and Tsuga are discussed, whereas for peninsular India the hardwoods Tectona grandis and Cedrela toona (now known as Toona ciliata) are the focus, with the statement that Michelia species are unsuitable for dendroclimatological analysis. Tertiary Araucarioxylon and Podocarpus are also mentioned, the former becoming extinct with increasing aridity and the second becoming endangered in southern and northeast India.
The second paper by Liang, Eckstein & Shao describes seasonal cambial activity of Pinus tabulaeformis at the northern limit of its natural distribution in semi-arid grassland in northern China. They found that cell division coincides with the highest monsoon precipitation and above 0°C daily minimum temperature and cambial activity coincides with the highest number of sunshine hours/day.
The third paper by Shao and seven others gives a climatic interpretation and dating of past events using a 3585 year chronology of Qilian Juniper (Juniperus przewalskii), a species endemic to northwest China. The chronology was based on an impressive 1438 series from 713 trees sampled from 22 archaeological sites, 24 living tree sites and 5 standing snags.
The fourth paper by Sho and four co-authors presents a 300 year record of ring width and stable isotope composition of Chamaecyparis obtusa from central Japan and discusses this in the context of hydrological and climatic implications.
The Qilian Mountains feature again in the fifth paper by Zhang and six others. Their study of two conifers (Juniperus przewalskii and Picea crassifolia) and two hardwoods (Populus davidiana, Betula platyphylla) provides a 1232 year record of climatic variability which the authors used to help interpret the Asian monsoon and the westerlies in northwest China over the last millennium.
Juniperus przewalskii is a popular species for dendroclimatological studies in the Qilian Mountains! In the sixth paper, Tian and four co-authors have described the regional mean temperature of May-June from 1700 to the present day in the area. Their reconstruction has extended the temperature record, correlated extremely high temperatures with droughts in the 1920s, and has provided long term temperature information documenting climate change in the region.
Guo and four others have used a 112 year chronology of Picea likiangensis and a 165 year chronology of Tsuga dumosa from Lijiang, northwest Yunnan in southern China for dendroclimatological purposes. This enabled them to recognise major wet periods in the 1860s, 1910s and 1940s, and drought periods from 1892-1905, 1914-24 and 1928-38. They also documented increasing precipitation from 1982 to 2003.
Fang and his eight co-authors discuss 14 tree ring chronologies along three altitudinal gradients for three mountain ranges in north central China using Pinus tabulaeformis, Picea crassifolia and Picea wilsonii. The ring width variation was more similar in the two spruces (Picea spp.). They discuss their results in relation to moisture stress, temperature and low and high frequency signals.
The final paper deviates from the dendroclimatological approach of most of the previous papers. Park & Lee studied South Korean coffin woods of a Diploxylon group pine, which they identified as probably Pinus densiflora. They estimated the trees to have been cut between 1633 and 1670, which is at least 100 years later than expected for this kind of grave.
In summary, this volume provides a large amount of detailed information on tree rings and dendroclimatology of temperate Asian conifers in particular. In this volume there is a strong bias towards China and especially the Qilian Mountains. The papers herein show a healthy research interest in tree rings in Asia and a strong desire to use the data collected in climate reconstruction. With increasing concerns regarding climate change and its potential impact on biodiversity, these studies are urgently needed and decision makers need to be encouraged to consider their implications. We all hear that past performance is no guarantee of future performance, but documenting past climatic events through growth rings certainly means that anticipating and modelling the future climate may be a realistic prospect. I thoroughly recommend this book to all those interested in climate, its effect on the growth of trees and what they can tell us about their environment.