麻豆淫院

(麻豆淫院) -- Far more wild plant species may be responding to global warming than previous large-scale estimates have suggested.

That鈥檚 the conclusion of a team of scientists, which included a UC San Diego biologist, that found that many plant species, which appear to not be affected by warmer spring temperatures, are in fact responding as much to warmer winters. The scientists detailed their findings in this week鈥檚 early online publication of the journal Proceedings of the National Academy of Sciences.

For years, scientists have accepted that certain species are flowering earlier each year due to changes in climatic conditions, but many species鈥攙arying around 30 percent, depending upon the region鈥攁ppeared not to be affected. These species had been assumed to be stable鈥攗nresponsive to global warming and thus outside of concern for how they will change with increasing rates of climate change.

But the team of researchers, led by Benjamin Cook, a climate modeler at the NASA Goddard Institute for Space Studies and Columbia University鈥檚 Lamont-Doherty Earth Observatory, found that the apparently stable species are, in fact, unquestionably feeling the effects of rising temperatures throughout the year.

]鈥淏ased on what we know from agriculture and plant physiology, we expect our results would be broadly applicable to many temperate regions where species are dormant in usually cold winters,鈥� said Elizabeth Wolkovich, who co-authored the study while a postdoctoral fellow in biology at UC San Diego. 鈥淲e expect that our results extend to many temperate habitats in Southern California, but we need more data for the best estimates and predictions of what future California springs will look like.鈥�

The study was part of efforts by a multi-national working group team, carried out at the National Center for Ecological Analysis & Synthesis, to better predict how plant leafing and flowering has and will continue to change with warming. The research team鈥攚hich included Camille Parmesan of Plymouth University's Marine Institute in the UK鈥攗sed data collected by citizen scientists in England and the United States to show that many species  (about 10 to 18 percent of species studied) advance their flowering with warmer springs, as have been previously found, but also delay warming with warmer winters鈥攁 so-called 鈥渃hilling requirement.鈥�

Many of the species that have not appeared to be altering their spring timing in recent years need cold winters to 鈥渢ell鈥� them when to become dormant and when to 鈥渨ake up鈥� in spring. With winters getting warmer, these species appear to be 鈥渨aiting鈥� for their cold cue, which can end up delaying their normal responses to the arrival of spring. The end result is species that show no change, or even a delay, in spring budding, leafing or blooming, in apparent contradiction with warming spring temperatures.

This new study resolves that contradiction for many species, indicating about two-thirds of 鈥渟table鈥� species are, in fact, sensitive to warmer springs, but even more so to warmer winters, with the end result being a confusion in timing of leafing, budding or blooming.

鈥淲e鈥檝e known about the need for cold winters to meet chilling requirements for many well-studied crop and lab species for a long time,鈥� said Cook. 鈥淏ut this is the first study to estimate how prevalent chilling requirements may be in wild plant communities and 鈥� further, to link to how plants change with global warming.鈥�

The scientists say further research is needed to figure out how such species will respond with continuing warmer winters and springs.

鈥淭he little data we have from other research suggests that species that do not meet their chilling requirements鈥攚hich is a highly possible outcome of global warming鈥攎ay flower erratically, that is far too early, or late or not at all,鈥� said Wolkovich, who is now at the University of British Columbia. 鈥淩ight now these species appear to have not changed much over time, but all our understanding of basic plant physiology suggests they will shift their flowering dramatically in the future.鈥�

鈥淭he key for future research will be understanding how we can predict what species and regions are most at risk of radical changes in their flowering due to warmer winters,鈥� she added. 鈥淔or that, we need far more data, especially from areas with few data鈥攖emperate regions throughout the US West, but especially in Southern California are some of the areas where we have almost no data on when species leaf and flower and how it has changed in recent decades. People can help by joining an observer network such as the National Phenology Network () or asking about opportunities at their local botanical clubs or natural history museums.鈥�