17 May 2017, Nature, Trees in eastern US head west as climate changes. Breaking from the general poleward movement of many species, flowering trees take an unexpected turn. Ecologists have long predicted that climate change will send plants and animals uphill and towards the poles in search of familiar temperatures. Such movements have increasingly been documented around the world. But a study now shows that changing rainfall patterns may be driving some tree species in the eastern United States west, not north. Songlin Fei, a forest ecologist at Purdue University in West Lafayette, Indiana, and his colleagues tracked the shifting distributions of 86 types of trees using data collected by the US Forest Service’s Forest Inventory and Analysis Program during two periods: from 1980 to 1995 and between 2013 and 2015 for all states. They found more species heading west than north, probably partly because of changing precipitation patterns, the team reported on 17 May in Science Advances1. “That was a huge surprise for us,” says Fei. This study suggests that, in the near-term, trees are responding to changes in water availability more than to temperature changes, he says. The team measured shifts in the centres of abundance for the 86 types of tree and found that over the past 30 years or so, 34% showed statistically significant poleward shifts at an average rate of 11 kilometres per decade. Forty-seven per cent made statistically significant westward shifts at an even faster rate — 15.4 kilometres per decade. Hardly any types of tree moved south or east. A new direction Most of the trees that shifted west were angiosperms, or flowering trees. Northbound trees were usually gymnosperms, which are mostly conifers in North America. Increased precipitation in the central United States could be one explanation for the angiosperms’ westward movement, says Fei. The increase in moisture is still subtle enough that only the more drought-tolerant and faster-growing flowering trees, which have more-efficient and robust vascular systems, can take advantage for now. Read More here
Tag Archives: forest response
1 March 2017, Climate News Network, Spring moving forward at record rate. Spring is arriving ever earlier in the northern hemisphere. One sedge species in Greenland is now springing to growth 26 days earlier than it did a decade ago. And in the wintry United States, spring arrived 22 days early this year in Washington DC, the national capital.The evidence comes from those silent witnesses, the natural things that respond to climate signals. The relatively new science of phenology – the calendar record of first bud, first flower, first nesting behaviour and first migrant arrivals – has over the last three decades repeatedly confirmed meteorological fears of global warming as a consequence of the combustion of fossil fuels. Researchers say the evidence from the plant world is consistent with the instrumental record: 2016 was the hottest year ever recorded, and it was the third record-breaking year in succession. Sixteen of the hottest years ever recorded have happened in the 21st century. Arctic spring And the most dramatic changes are observed in the high Arctic, the fastest-warming place on the planet, according to a study in Biology Letters. As the polar sea ice retreats, the growing season gets ever longer – and arrives earlier. The pattern is not consistent: grey willow sticks to its original timetable, and dwarf birch growth has advanced about five days earlier for each decade. But the sedge, almost four weeks ahead of its timetable in a decade, holds the record, according to a study that observed one plot at a field site in West Greenland, 150 miles inland, for 12 years. Read More here
29 September 2016, The Conversation, Putting carbon back in the land is just a smokescreen for real climate action: Climate Council report. Just as people pump greenhouse gases into the atmosphere by burning fossil fuels, the land also absorbs some of those emissions. Plants, as they grow, use carbon dioxide and store it within their bodies. However, as the Climate Council’s latest report shows, Australia’s fossil fuels (including those burned overseas) are pumping 6.5 times as much carbon into the atmosphere as the land can absorb. This means that, while storing carbon on land is useful for combating climate change, it is no replacement for reducing fossil fuel emissions. Land carbon is the biggest source of emission reductions in Australia’s climate policy centrepiece – the Emissions Reduction Fund. This is smoke and mirrors: a distraction from the real challenge of cutting fossil fuel emissions.Land carbon Land carbon is part of the active carbon cycle at the Earth’s surface. Carbon is continually exchanging between the land, ocean and atmosphere, primarily as carbon dioxide. In contrast, carbon in fossil fuels has been locked away from the active carbon cycle for millions of years. Carbon stored on land is vulnerable to being returned to the atmosphere. Natural disturbances such as bushfires, droughts, insect attacks and heatwaves, many of which are being made worse by climate change, can trigger the release of significant amounts of land carbon back to the atmosphere. Changes in land management, as we’ve seen in Queensland, for example, with the relaxation of land-clearing laws by the previous state government, can also affect the capability of land systems to store carbon. Burning fossil fuels and releasing CO₂ to the atmosphere thus introduces new and additional carbon into the land-atmosphere-ocean cycle. It does not simply redistribute existing carbon in the cycle. Read More here
9 September 2016, The Conversation, EcoCheck: the Grampians are struggling with drought and deluge. Our EcoCheck series takes the pulse of some of Australia’s most important ecosystems to find out if they’re in good health or on the wane. The Grampians National Park is a large conservation reserve, sprawling across 168,000 hectares embedded in western Victoria’s agricultural landscape. With a rich cultural heritage and regionally important flora and fauna, it is a hugely significant area for conservation. But in recent years it has been subjected to a series of major wildfire events, a flood, and long periods of low rainfall. Our research shows that this has sent small mammal populations on the kind of boom-and-bust rollercoaster ride usually seen in arid places, not temperate forests.The fire and the flood We began studying the Grampians in 2008, investigating how small mammals had responded to a catastrophic wildfire that burned half of the national park in 2006. What started as a one-year study has turned into a long-term research program to investigate how the past few years of hypervariable rainfall and heightened bushfire activity have affected the animals that live in the park. Fortunately (for our study, at least), the beginning of our research in 2008 was in the middle of a long run of very poor rainfall years, as the Millennium Drought reached its height. The drought was broken at the end of 2010 by the Big Wet, which led to well-above-average rainfall and floods in the Grampians. But soon after, rainfall rapidly dipped back to below average. It has stayed there ever since. We also saw two more major fire events, in 2013 and 2014, which together with the 2006 fire burned some 90% of the Grampians landscape. Read More here