The phenology & future of winegrapes
Understanding phenological hyperdiversity in Vitis vinifera
Winegrapes (Vitis vinifera ssp.) are one of the world's most lucrative and important crops, and also one of the most responsive to climate, with some researchers suggesting terroir equates to climate. A major way this climate sensitivity is exhibited is through phenology---especially the timing of budburst, flowering and veraison. Winegrape varieties (e.g., Pinot Noir versus Cabernet Sauvignon) show high diversity in their phenology---and related temperature requirements for flowering and veraison.
Given their high responsiveness to climate, climate change impacts on winegrapes have the potential to be quite high, yet variation between varieties in their temperature requirements and tolerances should provide some buffering if viticulturists understand this variation and can build upon and develop it. Understanding this variation, however, requires improved studies of phenology that can tease out genetic versus environmental drivers of phenology to build better models of how temperature triggers phenological events, how these triggers vary across varieties and the underlying genetic architecture that creates the hyperdiversity in climate requirements between varieties.
Working with Dylan Burge, Kim Nicholas, and Andy Walker, we are combining phenological observations from a common garden with genetic surveys of winegrapes to (1) build robust phenological models of the diversity of temperature requirements between varieties and (2) identify the genetic regions that map to this phenological variation. Our major goal is to understand how genetic diversity predicts phenological variation in order to improve prediction and forecasting of variety-level responses to climate change, with possible implications for breeding improved varieties for novel climates.
Cross-continental coherency in climate forcing of wine grapes
Understanding how climate change will affect agriculture is a critical goal of modern global change research, yet progress towards this goal is stymied by disparate crops and varying agricultural practices as well as little spatially and temporally extensive data. Wine grape records represent some of the most long-term recorded data on earth (harvest records in Europe stretch back over 1,000 years) and information on differing practices is often available. Working with Kim Nicholas, and Leanne Webb (Melbourne University and CSIRO) we are compiling data to compare climate forcing of grape harvests from Australia, Europe and North America. We're forever in the early stages of getting this project off the ground, however, Kim presented some results in her talk 'Trends in Climate and Phenological Changes in California and Australia' at the American Society of Enology and Viticulture meeting (June 2011).
The roles of cimate change and drought in driving early harvests
Climate change has altered the timing of winegrape harvests. Across France and globally grapes mature earlier by days and weeks compared to several decades ago. Understanding the climatic drivers of these earlier harvests requires long-term records and teasing out the often intertwined drivers of fruit maturation: temperature and drought.
Ben Cook and I are combining long-term harvest records from across France (collated by Daux et al. 2012) with reconstructions of temperature and drought to examine the drivers of early harvest over the previous centuries and more recently.