Seminar 16th April 2013 4 p.m. Highfield Campus, Building 6 (Nuffield Theatre, Room 1077
S3RI Special Seminar: Wildfires in South Africa; Cherry Trees in Japan
Professor Alan Gelfand
Duke University
- Web page
- http://www.isds.duke.edu/~alan/
- Submitter
- Luke Goater
We consider two challenging ecological problems and show how they are naturally investigated using spatial survival models with time varying covariates. The ?rst problem involves explanation of the occurrence of wild ?res. This process is of interest because over half of the world’s terrestrial ecosystems depend on ?re to maintain ecological structure and function and the ecological role of ?re regimes can be strongly in?uenced by weather and climate. To undertake this analysis, we developed an extensive database of observed ?res with high-resolution meteorological data to explore ?re regimes in the Mediterranean ecosystem in the Cape Floristic Region (CFR) of South Africa during the period 1980-2000. We need to consider the in?uence of seasonally (quarterly) anomalous weather on ?re probability. In addition to these local-scale in?uences, the Antarctic Ocean Oscillation (AAO) is a potentially important large scale in?uence with regard to global circulation patterns.
The second involves explaining ?rst ?owering times. The objective here is to learn about changes in the length and onset of the growing season. This process has to be examined at individual tree/plant level and in response to weather, in particular daily temperature, rather than aggregating to climate. We are broadly interested in comparison of ?rst ?owering time (or bud burst) across species but here we focus on explaining spatial variation in ?rst ?owering time. We consider ?rst ?owering dates for trees of a single species in Japan at 45 locations over 52 years, collected through 2009. The challenge with this process is to provide suitable functions of the weather - heating and chilling functions - to employ in the explanation. The di?culty is that these functions are not explicitly de?ned since they require measurement beginning from unknown starting dates as well as unknown thresholds. We have uncertainty in the speci?cation of the functional covariates. We present both analyses and our ?ndings along with some future challenge