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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)