Environmental Change Institute

New study examines the flow of ecological energy across old-growth forests, logged forests and oil palm. The study surveys mammal and bird species across these landscapes to calculate food energetic pathways: how photosynthetic energy cascades from sunlight to be distributed among organisms. Relative to energy flow in old-growth forests, study finds 2.5 times more total energy flows in logged forests. The study findings question the use of the word 'degraded' to describe logged tropical forests. Logging affects many of the world's tropical forests, and such forests are often considered degraded because they have lost vegetation structure, biomass and carbon stocks. But there has rarely been analysis of whether the ecological health and functionality of these ecosystems are similarly degraded. A new study by researchers at the University of Oxford, finds that logged rainforests are treasure-troves of healthy ecological function and should not be written off for oil palm plantations. Lead author Professor Yadvinder Malhi, Professor of Ecosystem Science at the Environmental Change Institute at the University of Oxford says, 'We were very surprised by how much more energy was flowing through the logged forests compared to the old-growth forest, and that it was flowing through the same diverse range of species found in the old-growth forest. We had not expected the logged forest to be so ecologically vibrant.' The research, 'Logged tropical forests have amplified and diverse ecosystem energetics', published in Nature tackles this issue through the perspective of ecosystem energetics -- the cascade of energy from plants to mammals and birds through the food they consume. The research team combined more than 36,000 tree, root, and canopy measurements with population data on 248 vertebrate species from old-growth forests through logged forests to oil palm plantations in Borneo. Remarkably, the study found that the ecological energy flow through the logged forest was 2.5 times greater than in the old-growth forest, before collapsing in the oil palm plantations. The logged forest supported similar or greater densities of almost all bird and mammal species. The authors emphasise that old-growth forests still hold immense ecological value and high carbon stocks, and need to be left intact where possible. But this study questions the labelling of logged forests as "degraded" when they are so ecologically vibrant. Such labelling can mean these logged forest landscapes are seen as lower priorities for protection and are cleared to make way for agriculture such as oil palm. Professor Malhi concludes: 'In tropical forests, and probably in many other ecosystems, not everything that looks broken, is broken.' The study required meticulous counting of almost all bird and mammal species in the remote study sites, as well as measuring the growth rates of trees and their leaves and roots. Dr Matthew Struebig, co-author and Reader in Conservation Science at the University of Kent added, 'In the early morning, ornithologists listened out for birds, while evenings were spent catching bats in special traps. Meanwhile, trail cameras and cage traps over 77,000 combined nights provided much-needed information on secretive and elusive mammals, from tree shrews, sun bears and elephants.' Dr Terhi Riutta, co-author, Post Doctoral Researcher at the University of Exeter added: 'This work would not have been possible without the many years of detailed fieldwork by our partners and research assistants in Malaysia, often in very tough conditions.' Professor Robert Ewers, co-author at the Department of Life Sciences at Imperial College London added, 'Ecologists often just study one aspect of an ecosystem, like its trees or its birds. This study shows how meticulous and joined-up research across a wide range of species can yield surprising and important new insights into the nature of ecosystems in a human-dominated world.'

A study found that a combination of global atmospheric warming and westerly winds shifting toward the poles will likely speed up the recession of mountain glaciers in both hemispheres. The study compared global temperature and wind changes with glacier snowline elevations in the Southern Alps of New Zealand and in the European Alps observed over the course of nearly four decades. The results show that under global warming, the poleward contraction of the westerly winds belts may accelerate warming and glacier melting. The results highlight the sensitivity of Earth's mountain glaciers to broad-scale atmospheric dynamics. The combination of global atmospheric warming and westerly winds shifting toward the poles will likely speed up the recession of mountain glaciers in both hemispheres, according to a UMaine study. Mountain glaciers freeze and gain mass when the climate cools, and melt and lose mass when the climate warms. The extent to which the fluctuations in mountain glaciers are reflective of local, regional and even hemispheric climate variations, however, is less clear, which has made it more difficult for scientists to use glacial data to interpret past climate dynamics and make predictions for the future. A team of researchers from the University of Maine conducted a National Science Foundation-funded study evaluating how atmospheric conditions are reflected in the mass fluctuations of mid-latitude glaciers on opposite sides of the Earth, comparing global temperature and wind changes with glacier snowline elevations (also called "equilibrium-line altitudes") in the Southern Alps of New Zealand and in the European Alps observed over the course of nearly four decades. Glacier extent is dependent on the height of the snowline in the atmosphere, below which ice melts, which in turn is determined by the temperature of the atmosphere. The data showed that the fluctuations in glacial snowlines reflected temperature changes over large regions of the atmosphere for the two mountain systems studied -- even on hemispheric scales. Moreover, the latitudes of westerly wind belts were found to be important for regulating the proportion of cold versus warm air masses that influence glacier melting and freezing. "This study really shows how intertwined Earth's climate system is. At first subtle shifts in the state of the climate system can create waves throughout the system that have far reaching consequences," says Alexander Audet, principal author of the study, who completed the research as a master's student at the University of Maine. He is now pursuing a Ph.D. at the University of Nevada, Reno. The results show that under global warming, the poleward contraction of the westerly winds belts may accelerate warming -- and glacier melting -- in the mid latitudes of both hemispheres. "These results highlight the sensitivity of Earth's mountain glaciers to broad-scale atmospheric dynamics. They are incredibly sensitive, physical thermometers, monitoring atmospheric conditions from the sea surface to the top of the troposphere. Reconstructions of past glacier change from glacial landforms may therefore help to provide quantitative insights into how large portions of the atmosphere behaved during past episodes of abrupt climate change, and in turn may offer clues into the climate dynamics of a warming world," says Aaron Putnam, co-author of the study and associate professor at the UMaine School of Earth and Climate Sciences. George Denton, UMaine professor at the School of Earth and Climate Sciences and the Climate Change Institute, also co-authored the report. Other co-authors of the study included Joellen Russell of the University of Arizona; Andrew Lorrey, who received his master's at UMaine and is now principal scientist of climate and environmental applications at the National Institute of Water and Atmospheric Research (NIWA) in New Zealand; Andrew Mackintosh of Monash University, Australia; and Brian Anderson at the Victoria University of Wellington, New Zealand.

To identify variations in climate across Maine wild blueberry fields at different times of the day and year, researchers analyzed annual and seasonal data from 1980-2020 for Washington, Hancock, Piscataquis, Waldo, Knox, Lincoln, Kennebec and York counties. They found that location, season and the time of day influence how fast temperatures are rising at wild blueberry fields due to climate change. The location, season and the time of day influence how fast temperatures are rising at Maine wild blueberry fields due to climate change, according to a new University of Maine study. To identify variations in climate across Maine wild blueberry fields at different times of the day and year, the research team led by Rafa Tasnim, a Ph.D. candidate in ecology and environmental sciences, analyzed annual and seasonal temperature, precipitation and snow cover data from 1980-2020 for Washington, Hancock, Piscataquis, Waldo, Knox, Lincoln, Kennebec and York counties. Understanding how warming patterns differ based on these factors can provide growers more targeted information about the possible effects of climate change on their fields, which allow for more tailored strategies to mitigate them. Over 41 years, temperatures rose at a faster rate in the fall, winter and summer in all eight counties, but not in the spring, according to researchers. The growing season for these wild blueberries has extended later into the fall, and the average first frost has been pushed back to December. The longer season, however, exposes blueberries to a greater risk of frost damage because they develop and mature before the late and last spring frosts occur, researchers say. Fields in Piscataquis and Washington counties are warming faster and experiencing longer growing seasons than other counties analyzed by researchers, although their average temperatures are not as high, according to study. The more eastern or closer to the coast the fields are, the faster they warm and the more at risk they are to frost damage. The team also found that minimum nighttime temperatures increased over the past 40 years at fields in all counties faster than those for the daytime maximums. The shift can result in wild blueberries producing more carbon dioxide than they absorb -- which can alter the carbon cycle -- because while warmer daytime and nighttime temperatures increase the rate of respiration, only daytime temperatures affect the frequency of photosynthesis. Researchers found no notable differences in snow cover or precipitation, save a significant increase in the latter in Washington County, from 1980-2020 across the eight counties. "I believe the outcomes from the analyses of this study have opened more room for further research to verify the responses of Maine's beloved wild blueberries to the dramatic seasonal and spatial climatic changes that they are and will keep experiencing," Tasnim says. "It would be vital and more beneficial for the growers if we research scientists can plan and recommend management strategies based on both the climate analyses that we have done as well as based on the wild blueberry plants' specific responses." Other researchers involved in the study, which was published in the journal Atmosphere, include Yongjiang Zhang, an assistant professor of applied plant physiology; Lily Calderwood, University of Maine Cooperative Extension wild blueberry specialist and assistant professor of horticulture; Sean Birkel, Maine state climatologist and faculty member with the Climate Change Institute and UMaine Extension; and Samuel Roberts, an undergraduate student in the Ecology and Environmental Science program of the University of Maine. It is "the first to access and report diurnal, seasonal, annual and spatial climate patterns for" Maine wild blueberry fields, they say. The study builds on previous research from Tasnim and her faculty colleagues exploring the effects of climate change on wild blueberries. Earlier research revealed that fields in Down East are warming faster than those for Maine as a whole, and that proper soil moisture management is more important to helping wild blueberries thrive, especially in the long term, than previously thought. Differences in warming based on location and time mean that some fields will benefit from rising temperatures some years and suffer during others, according to researchers. They recommend further investigations into how wild blueberries respond to experiencing warmer day and night temperatures, summers, falls and springs, as well as climate extremes. "We showed different climate change patterns in different seasons and locations. Also, there is an increase in extreme climate events, so we need to study how wild blueberries will respond, and develop new management techniques to enhance the resilience of this crop and protect it from climatic changes," says Zhang.