{"id":7387,"date":"2014-02-24T00:53:02","date_gmt":"2014-02-24T05:53:02","guid":{"rendered":"https:\/\/college.unc.edu\/?p=7387"},"modified":"2024-07-02T14:36:01","modified_gmt":"2024-07-02T14:36:01","slug":"ever-greener","status":"publish","type":"post","link":"https:\/\/collegearchive.unc.edu\/?p=7387","title":{"rendered":"In the shade of the longleaf pine, some N.C. plants find relief from global warming"},"content":{"rendered":"
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\"U.S.<\/a>
U.S. Geological Survey<\/figcaption><\/figure><\/p>\n

Over the past two decades, U.S. forests have grown denser. More wooded lands are being protected from development, and more logging companies are replanting forests to grow back thicker than before they were cut. Trees pull carbon dioxide out of the air, and some scientists think that more trees will mean slower global warming. But trees may also be blunting the effects of climate change, says UNC plant ecologist Peter White, just by blocking the sun\u2019s\u00a0rays.<\/p>\n

Every type of plant or animal has a range of temperatures it likes best. \u201cWe all know that we like to sit in the shade on a hot summer day,\u201d White says. Just like people, some plants need both sunlight and shade to thrive\u2014even certain trees, such as the eastern hemlock, rely on the cover of taller trees to block excess sunlight. About 60 percent of land in North Carolina is forest, meaning that many of the state\u2019s plants, animals, and people are using the tree canopy for\u00a0shade.<\/p>\n

With a team of researchers from Europe, the United States, and Canada, White revisited plots of forest that had been studied decades ago\u2014on average, about 35 years\u2014to see how they\u2019ve changed as temperatures have risen. (Winter 2014 cold snaps notwithstanding, the average temperature in North Carolina has gone up by about two degrees Fahrenheit since 1970.) White contributed data from North Carolina\u2019s Great Smoky Mountains, where back in the 1970s he and students studied a blight that was killing dogwood trees. Now, like other researchers in the study, White has found that tree cover affects how well plants can stand up to global warming. In places where tree cover is thinner, plants that like relatively cool temperatures have been dying off as temperatures rise. Where the tree cover is thicker, those kinds of plants are faring\u00a0better.<\/p>\n

This means, White says, that \u201cthe thickness of the forest is intervening to make climate change look more mild than it is. If there\u2019s a disturbance\u2014such as a hurricane, a fire, or harvesting\u2014then you\u2019ll see stress and rapid change.\u201d Global warming, already felt in the forest canopy and in openings and disturbed areas, could spread into thicker forests as the demand for wood pellets increases. Classified by the European Union as a renewable energy source, wood pellets are made from whole trees and the demand for them is increasing logging up and down the east coast, White\u00a0says.<\/p>\n

\u201cAll over the eastern forests of the United States, before the wood pellet issue, the rate of harvest compared to the thickening of the forest has been relatively low,\u201d White says. This is in part because of more vigilant forest fire prevention\u2014and having fewer fires, scientists say, has actually decreased<\/em> diversity in our forests. Some species use the heat or smoke from fire as a trigger to release their seeds. When there are fewer fires, forests grow more densely, apparently protecting some species against the effects of global warming while hurting\u00a0others.<\/p>\n

One of White\u2019s students, Bianca Lopez, may help us predict what that warmer future will do to North Carolina plants. For her dissertation, she\u2019s comparing plots of forest in more populated parts of the Triangle\u2014Chapel Hill, Durham, Raleigh\u2014with more rural sites in places like Butner and Creedmore. By coincidence, Lopez says, the temperature difference between urban and rural forests\u2014about 3.6 degrees Fahrenheit\u2014is comparable to the increase in temperature that scientists expect to see between now and the end of the century. In some ways, urban forests are a model for what rural forests will look like as temperatures\u00a0rise.<\/p>\n

Lopez goes to these plots of forest around the Triangle and counts plants from tall pines to tiny wildflowers. So far, she says, she\u2019s finding that the minimum winter temperature\u2014the coldest it gets on the coldest night of the season\u2014is the main factor that explains differences in which plants are found where. White, too, has looked at temperature graphs and thinks that minimum winter temperature has the largest effect on plants. As that coldest winter temperature rises, plants that don\u2019t do well with heat, like the beloved dogwood, could be in trouble. Others, like the southern magnolia, will multiply and spread northward. White\u2019s student Jennifer Gruhn, now a grad student at Washington University, has already found hints that magnolias have multiplied around the UNC campus since temperatures started rising in the late\u00a01970s.<\/p>\n

A once healthy forest that could recover from a fire, a hurricane, or logging may not be able to do so as temperatures rise. \u201cIf we want to understand the threat of climate change to North Carolina,\u201d White says, \u201cwe can\u2019t just put out a thermometer to see whether it\u2019s getting warmer.\u201d The density of a forest and the rate of harvest will tell us which forests are most at risk, and which can better stand up to rising\u00a0temperature.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Peter S. White<\/a> is a professor of biology in the College of Arts and Sciences, and director of the North Carolina Botanical Garden. Bianca Lopez is a graduate student in the Curriculum for the Environment and Ecology. One of Lopez\u2019s advisors, ecologist Dean Urban at Duke University, came up with the idea to find warmer and cooler forests in the area by looking at satellite maps of\u00a0radiation.<\/p>\n

by Susan Hardy<\/h2>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Trees pull carbon dioxide out of the air, and some scientists think that more trees will mean slower global warming. But trees may also be blunting the effects of climate change, says UNC plant ecologist Peter White, just by blocking the sun\u2019s rays.<\/p>\n","protected":false},"author":4,"featured_media":7388,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[21],"tags":[2138,209,36,2139],"class_list":["post-7387","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-forestry","tag-global","tag-unc","tag-warming"],"_links":{"self":[{"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/posts\/7387","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7387"}],"version-history":[{"count":2,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/posts\/7387\/revisions"}],"predecessor-version":[{"id":46487,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/posts\/7387\/revisions\/46487"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=\/wp\/v2\/media\/7388"}],"wp:attachment":[{"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7387"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7387"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/collegearchive.unc.edu\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7387"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}