As global temperatures rise, the most threatened ecosystems are those that depend on a season of snow and ice, scientists from the United States’ Long Term Ecological Research (LTER) Network say. “The vulnerability of cool, wet areas to climate change is striking,” says
Julia Jones, a lead author in a special issue of the journal BioScience released 6 April 2012, containing a section of six studies dedicated to long-term ecosystem effects of environmental change, featuring results from more than 30 years of LTER, a program of the National Science Foundation (NSF).
In semi-arid regions like the southwestern United States, mountain snowpacks are the dominant source of water for human consumption and irrigation. Research by Jones and her colleagues shows that as average temperatures increase in these snowy ecosystems, a significant amount of stream water is lost to the atmosphere. The study involves more than thirty years of data from 19 forested watersheds across the country. All of the study sites provide water to major agricultural areas and to medium and large cities.
But, like many long-term studies, this one revealed a surprise. Water flow only decreased in the research sites with winter snow and ice. Jones explains, “Streams in dry forested ecosystems seem more resilient to warming. These ecosystems conserve more water as the climate warms, keeping streamflow within expected bounds.
A range of factors can impact watersheds, from human influence past and present, to El Niño climate oscillations. “Long-term records are finally long enough to begin to separate the effects of each,” Jones points out. “This research shows both the vulnerability and resilience of headwater streams. Such nuanced insights are crucial to effective management of public water supplies.”
Ecosystems are changing worldwide as a result of shrinking sea ice, snow, and glaciers, especially in high-latitude regions where water is frozen for at least a month each year (the cryosphere). Scientists have already recorded how some larger animals, such as penguins and polar bears, are responding to loss of their habitat, but research is only now starting to uncover less-obvious effects of the shrinking cryosphere on organisms. They include dislocations of the relationships between predators and their prey, as well as changes in the movement through ecosystems of carbon and nutrients. The changes interact in complex ways that are not currently well understood, but effects on human populations are becoming apparent. Disappearing ice on land and the resulting sea-level rise will have far-reaching social, economic, and geopolitical impacts, the authors of one of the studies note. Many of these changes are now becoming evident in the ski industry, in infrastructure and coastal planning, and in tourism. Significant effects on water supplies, and consequently on agriculture, can be predicted.
Surprising and transformative results are common in LTER, which comprises 26 sites in North America, Puerto Rico, the island of Moorea, and Antarctica. The network has amassed more than 30 years of data on environmental recovery and change. In contrast to most grant-funded research, which spans only a few years, LTER studies are often sustained over decades, documenting gradual changes and long-term variability that often cannot be revealed by short-term studies. The BioScience issue reveals how the network’s diversity of long-term research approaches, including detailed observations and experiments, environmental gradient studies, and complex simulation models, can contribute to solutions in an era of unprecedented environmental change.
There are other reasons the BioScience retrospective is timely. Demand for natural resources is increasing with global human population, which the United Nations projects to reach at least 9 billion by 2050. Another paper in the special issue shows how long-term ecosystem data can help researchers simulate a region’s future based on a range of possible human actions. “For example, how might forest ecosystems change if more people begin to use wood to heat their homes?” poses Jonathan Thompson of the Smithsonian Conservation Biology Institute, the lead author of this paper.
The above news item is reprinted from materials available at LTER and AIBS via ScienceDaily. Original text may be edited for content and length.
(Sources: LTER Network News, 06.04.2012; AIBS Publications, April 2012; ScienceDaily, 06.04.2012)