No.
59, August 2007
What's so special about drylands?
by Mark Losleben and Wim van Leeuwen
"...phenological events and their timing are now widely recognized as ideal indicators of how local and global climate changes are affecting ecosystems at local to global scales."
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Introduction
All of these are examples of phenology: that is, the occurrence (and the study by humans) of periodic plant and animal life cycle events that are influenced by environmental changes, especially seasonal climate-driven variations in temperature and precipitation. Important phenological events, or "phenophases," include:
Variations in phenophase affect the abundance and diversity of organisms, their inter-interactions with other species, the roles they play in a given ecosystem, and their effects on fluxes in water, energy, and chemical elements at scales from local to global and from minutes to centuries. The importance of phenology to humans(Back to top) Over the past decades, phenology has taken on new importance as a tool for understanding and addressing a variety of complex problems, such as:
Phenology and global warming(Back to top) That climate changes are indeed occurring, and are in large part due to human activities, is by now widely accepted. Climate variability and extreme weather events are also expected to increase, affecting not just people but also the intricate timing of development phases of all living organisms that are part of the Earth's natural systems. This latter point is crucial: if our biological and climate calendars start to run out of sync due to these global changes, there will be significant ecological and socio-economic consequences that will seriously affect humans. For example, it has been well documented that, during the 20th century, many parts of the world experienced warmer surface air temperatures that caused earlier and longer growing seasons. But what if this means that flowers start blooming before any insects have hatched, or any migrating pollinators are around, to pollinate them? It is easy to see that ultimately, such changes could filter up the food chain to have drastic effects on our food supply. Phenological data can help us document and measure the occurrence of such changes. And phenological information is useful for more than just understanding current conditions of climate change. When spatially extensive sets of phenological data are integrated with short- and long-term climatic forecast models, powerful tools emerge to assist human adaptation to ongoing and future climate change. Given sufficient observations and understanding, these tools can be used as a predictor for other processes and variables of importance at local to global scales. Ultimately, phenological data could drive a variety of ecological forecast models with both theoretical and practical applications., enabling answers to critical questions about our changing planet and how humans can best adapt to this change through increased understanding of earth systems interactions on a scale never before possible. At present, though, broadly distributed phenological data sets that take advantage of environmental gradients (1) are almost non-existent, because such gradients are difficult to construct without a centralized data resource. In order for phenological modeling to improve our understanding of environmental variability as a cause and/or consequence of complex problems like climate change, we need networks that can amass large numbers of phenological observations and provide tools to analyze these data at multiple scales. Fortunately, a unique convergence between rapid technological change and growing public and scientific interest is making it increasingly feasible to establish such networks. Phenology internationally(Back to top) As the importance of phenological information to climate change studies was recognized, steps were taken to address these problems, and the year 2000 saw the successful launch of a proposal to set up the European Phenology Network. Incorporating several previously established programs, the EPN aims to improve monitoring, assessment and prediction of climate-induced phenological changes and their effects in Europe. Phenology in the United States(Back to top) The USA-NPN as envisioned has great potential to help safeguard and procure ecological goods and services throughout the country. With this potential in mind, the goals for the network are to:
The framework for the USA-NPN is a four-tiered, expandable structure representing different levels of spatial coverage and quality/quantity of phenological and related environmental information: |
The USA-NPN's first official campaign was "Project Budburst," a nation-wide data-gathering campaign was held during the spring 2007 growing season (March-June 2007). This project encouraged citizen scientists to track local flowering times of a selected set of species, entering their observations into the project's web site. At the same time, work also began on linking remote sensing (that is, landscape-scale phenology) and surface phenology measurements for several sites and ecosystems across the US. In addition, the USA-NPN will search for natural history collections and historical data sets to extend the significance of current observations. Region-specific networks in the USA-NPN(Back to top) Regional organization is currently highest in the northeastern US, but activities towards establishment of a Southwest Regional Phenology network are also underway. These include the upcoming joint conference of the American Society for Photogrammetry and Remote Sensing, US Southwest region, and the US National Phenology Network, to be held in Tucson, Arizona, on October 5, 2007. The Southwest Regional Phenology Network will be particularly well suited for arid lands studies, such as:
Conclusion(Back to top) Setting up such networks is a big job, but as the examples of the European Phenology Network and the USA-NPN show, there is also excellent potential for such networks to be established by leveraging already-existing data and networks. For drylands in particular, where natural variations in climate have always been more extreme than in temperate regions, the need for phenological networks is perhaps most immediate. The fragility of drylands ecosystems means that they are potentially more subject to irreversible changes triggered by warming climates, and potentially less resilient in successfully adapting to such changes. Phenology networks are an emerging means of providing the knowledge and tools we need to successfully meet the challenges of dealing with climate change, in drylands and elsewhere, over the course of the 21st century. Endnotes
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Mark Losleben (losleben@email.arizona.edu)
is the Assistant Director of the USA-National Phenology Network, working out
of the USA-NPN's National Coordinating Office in Tucson, Arizona. Dr. Wim van
Leeuwen (leeuw@ag.arizona.edu) is
Assistant Professor, Office of Arid Lands Studies and Dept of. Geography & Regional
Development, University of Arizona.
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European Phenology Network
http://www.dow.wau.nl/msa/epn/index.asp
Existing phenological networks throughout the world
http://www.pik-potsdam.de/~rachimow/epn/html/frameok.html
USA-NPN
http://www.usanpn.org/
Project Budburst
http://www.windows.ucar.edu/citizen_science/budburst/