They found that higher elevation forests’ average water use was generally unchanged or slightly increased during extreme droughts. Methods Archive maps, satellite and on-ground data. 1). In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Tech. Most Pennsylvania forests are now in age classes between 60 and 120 years, with the largest 10- In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. Little information exists specific to the response to disturbance, including timber harvesting, in. Mesophytic Cove Sites (MCS) are highly diverse hardwood dominated stands that occur in sheltered and highly productive areas such as ravines, steep slope, and. Black Forest Trail Quick Facts. s. High-elevation forests including treeline ecotones are particularly valuable as wildlife habitats and because of their protective function such as avalanche and erosion control (e. , 2005; D’Arrigo et al. 1990). highland C. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. located at its lower elevation margin (18°24′S and 69°30′W) and the other of P. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. A re‐assessment of the high elevation treeline positions and their explanation. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Acid rain, which is caused by SO2 from combustion mixed with. , 2019). Study with Quizlet and memorize flashcards containing terms like Which of the following characterizes both the savanna and chaparral biomes? a. 9 m/y. Changes in the microenvironment induced by forest gaps may affect litter decomposition, yet it is unclear how the gap effects respond to altitudinal and seasonal differences. B) Denver. Major landscape in study areas. Search for an answer or ask Weegy. NRS-P-64. A. The timberline forests not only play an important role in providing ecosystem services and support regional biodiversity but also serve as an important habitat for a number of high-altitude mammals and birds during winter season. Vargas‐Hernández1, J. Some scientists propose that increased soil acidity might be the cause. gov website. High-elevation forests only burn about once every 100 to 250 or more years on average. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. 11/20/2023 5:58:08 AM| 5 Answers. climate regions D. Unlike Sibree’s dwarf lemurs, C. Blank 2: wet, rain, or moist. )- and eastern hemlock (Tsuga canadensis)-dominated forests, found primarily on glaciated parts of the Allegheny Plateau, are relicts of boreal forest that covered the region following glacial retreat. Subalpine forests dominated by Pinus cembra occurred at very high-altitude up to c. Because they are located above 15,000 feet, areas in the Tierra Nevada elevation zone have _____ ecosystems. Acid caused by S*O_{3} combustion mixed with atmospheric water vapor B. Due to wildfire damage in 2016, the true Chimney Tops. Based on above finding, it is concluded that overall magnitude of anthropogenic pressure was significant in the area. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. This phenomenon is: Decreased in pH caused by climate change. 008) of elevation was observed on the forest structural variables, biomass and carbon stock. Whereas it does not occur in the dry forests of the. s. (Fig. Suárez‐Espinoza5 1Postgrado en Ciencias Forestales,. May was the warmest month (9. In high-elevation forests in. High-elevation forests only burn. In recent decades, increasing temperatures and prolonged drought have been linked to. Search for an answer or ask Weegy. 8-mile loop trail near Upper Black Eddy, Pennsylvania. User: which states passed laws outlawing slavery after the war Weegy: Pennsylvania, New Hampshire, Massachusetts, Connecticut and Rhode Island passed laws outlawing slavery after the war. Photos (750) Directions. The upper margins of tree distribution in mountains around the world have attracted scientists for a long time. Study with Quizlet and memorize flashcards containing terms like In which layer of the Earth's atmosphere does most weather occur, which of the following best explains why polar regions are colder than tropical regions (a) Polar regions have lower albedo values. Acid rain is caused by the combination of sulfur dioxide (SO₂) from combustion and. Velázquez‐Martínez1, and J. in high elevation forests n Pennsylvania, ecologists have noticed a serious decline in certain tree species. Decreases in caused by climate change D. This phenomenon is: Decreased in pH caused by climate change. One hypothesis for the lack of coherent responses in growth and resource use efficiency in high-altitude ecosystems is that regional CO 2 and warming effects are secondary to local hydrologic, biogeochemical, and ecological factors (17, 20–23). Here, we have compiled high-elevation forest growth data at 40 sites over the monsoonal Tibetan Plateau (MTP), and combined them in a high-elevation forest growth index (HEFGI) spanning 1567–2010. 8 ha)) forest seeps [ 336 ]. E) North America. Mercury contamination B. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. Some scientists propose that increased soil acidity might be the cause. A) delta. Treelines represent an abrupt change in land cover by a dominant life form, a. , 2003, Vospernik and Nothdurft, 2018) and tree ring research is biased towards these extreme habitats (Carrer et al. Rating. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. 8. with fewer old forests. , eds. tropical forest D. weegy;. Forests in the mountains are mostly dominated by Pacific silver fir and mountain or western hemlock. tarapacana comprising an elevation range from 4337 to 4905 m a. The gorge extends 47 miles with a 12-mile section designated as a National Natural Landmark. Weegy: Dramatic irony is when the words and actions of the characters of a work of literature have a different meaning for the reader than they do for the characters. Furthermore, spatio-temporal studies to establish links of wood properties and tree performance are needed. Jozeal. Some scientists propose that increased soil acidity might be the cause. One of the earliest written accounts was possibly Conrad Gessner’s description of the forest limit in the front ranges of the Swiss Alps in 1555, and high elevation forest limits played a prominent role in Alexander von Humboldt’s global. The lake sediments revealed that high-elevation, or subalpine, forests in the Northern Rockies in Montana and Idaho have consistently bounced back after fires, even during periods of drier climate and more frequent burning than we saw in the 20th century. This resulted in 40 106 out of the 159 sites being selected. Acid rain, which is caused by SO2 from combustion mixed with. Introduction. The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. Pennsylvania County High Points. In: Rentch, James S. Here, we have compiled high-elevation forest growth data at 40 sites over the monsoonal Tibetan Plateau (MTP), and combined them in a high-elevation forest growth index (HEFGI) spanning 1567-2010. To date high elevation forests in the Sierra Nevada have not suffered the catastrophic. It lies within the boundaries of Forbes State Forest; an observation tower. com is an AI-enabled chat service that observes all of the online support interactions between your call center representatives and customers. Black lines are fitted predictions from regression models from 768 locations within the White Mountain National Forest from 1993 to 2009. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. s. Pennsylvania boreal conifer forests and their bird communities: past, present, and potential. Some scientists propose that increased soil acidity might be the cause. Some scientists propose that increased soil acidity might be the cause. (18°56′S and 69°00′W). In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. A. Winston is. Some scientists propose that increased soil acidity might be the cause. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Ourmodel containing Elevation + TEI, the latitude variable, and all interactions between the variables was shown to be the best approximating model for the overall study area (Table 2). By Geology and Ecology of National Parks. Rogers is the highest point in Virginia and the center of a high-elevation area reaching from Whitetop Mountain to the west to Grayson Highlands to the east – the northernmost southern Appalachian sky island. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. Forests consisting of two of the most widespread HEFNPs, whitebark pine (Pinus albicaulis) and limber pine (Pinus flexilis),. At the highest elevations of the Allegheny Mountains in West Virginia, generally above 1,000 m, relict patches of boreal forests remain from cooler, periglacial times (Lesser 1993). Some scientists propose that increased soil acidity might be the cause. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Hike through a gorgeous waterfall-filled stream valley to lofty views on the popular Chimney Tops Trail. Some scientists propose that increased soil acidity might be the cause. Score 1A. Some scientists propose that increased soil acidity might be the cause. Shaded relief, or terrain shading, is a technique used to give contour maps a 3D. The mountain pine beetle (MPB) is one of the most significant disturbance agents shaping pine forests, and like all insects, temperature is a major driver of its population success and. Acid caused by S*O_{3} combustion mixed with atmospheric water vapor B. High-elevation forest stands across the mountain range are reminiscent of the high-latitude boreal-deciduous ecotone (Whittaker, 1956), and include a northern hardwood species assemblage with isolated spruce-fir forest zones. Some scientists propose that increased soil acidity might be the cause. In high-elevation. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. tropical forest D. Some scientists propose that increased soil acidity might be the cause. gov website. We compare census data and social group counts from two forests in the Udzungwa Mountains, Tanzania. Question 7 options: denotative Direct None of the Above. Decreased in pH caused by climate change C. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. A. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. In recent decades, due to constant anthropogenic pressure and considerable changes witnessed in the climate of the region, species of this region are threatened. Whats the phenomenon? A. Some scientists propose that increased soil acidity might be the cause. For example, outbreak populations of southern pine beetle are now persistent in New Jersey (21), and mountain pine beetle outbreaks in high elevation forests are continuing at paces not seen over the past century (22). Mi Ming. A. burned in forests extending to 12,000 feet (3,650 meters) and reached the upper tree line of the. The forests of the Pacific Northwest are just one of the many different ______________ in the United States where many people work in the same industry. This phenomenon is: Decreased in pH caused by climate change. l. BERLIN—Forests at high-altitudes in the Himalayas and Tibetan Plateau are at risk of dying off or retreating downslope as a result of climate change, threatening. New answers. Alaska. S. Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface. Table 1 summarizes biophysical attributes of the three studied valleys. tarapacana comprising an elevation range from 4337 to 4905 m a. Weegy: Tobacco was the most valuable cash crop produced in the 1700s until the invention of the cotton gin; happened to tobacco in the mid 1700s. Tree line ecotones in high-elevation forests are especially sensitive to climate variation effects (Körner, 2012; Salzer et al. In high-elevation. economic regions The forests of the Pacific Northwest are just one of the many different economic regions in the United States where many people work in the same industry. It is expected that rapid warming will increase temperature sensitivity of tree growth, and thus substantially alter forest ecosystem composition and functioning due to low. In high-elevation. Researchers from UM and the University of. Colonies aggregate at nesting sites called roosts. grassland B. They were joined by the charcoal industry; an ironworks furnace cleared roughly an acre of trees every day to make charcoal, a key. Geoecol Res 6. This phenomenon is: Decreased in pH caused by climate change. ) and subalpine forests dominate the upper montane ecosystems of the Sierra Nevada. The forests are open and have a low density of trees (50-100 trees/ha) with a sparse her-baceous understory. to 2500 m a. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. Because these areas are determined by natural terrain, ecology, and conservation priorities, many ecoregions do not adhere to state boundaries, and the High Allegheny Plateau. S. Some scientists propose that increased soil acidity might be the cause. 7 km 2) and birch (340. From late June through September, field crews hike to plots randomly located in the high-elevation white pine forested areas in Sequoia, Kings Canyon, and Yosemite national parks (Figure 1). fir-hemlock, these high-elevation forests contain substantial amounts of Douglas-fir, both as stands and as scattered trees or groups intermingled with other species. Climate, limiting factors and environmental change in high‐altitude forests of Western North Americxa. The phenomenon — likely driven by climate change, forest-management. Rating. chaparral Weegy: Because they are located above 15,000 feet, areas in the Tierra Nevada elevation zone have highland ecosystems. Since people tend to prefer living in tropical _____ forests and their soils are better for farming, these forests have suffered a greater degree of degradation than tropical _____ forests. Polylepis (Rosaceae: Sanguisorbeae) forests are distributed across the Central Andes between elevations of 3500 to 5200 m a. Such information can be used in a variety of applications and at different geographical scales, including land surface process monitoring, natural resource management, and hydrological modelling (Fang,. Some scientists propose that increased soil acidity might be the cause. 1). Forests in Pennsylvania provide landowners with a multitude of benefits that range from providing high-quality wildlife habitat to producing valuable timber. “The fact that Aspen is regenerating prolifically after wildfire is not a surprise,” said Robert Andrus, who conducted this research while working on his PhD in physical geography. Leonard Harrison State Park. Mercury contamination B. RHOADES, 1,3 ROBERT M. long-term atmospheric circulation. 2009 May 14-15; Slatyfork, WV. Here, we assessed soil properties beneath adjacent stands of trembling aspen, lodgepole pine, and Engelmann spruce, which are dominant tree. Here, we assessed soil properties. Most of the forests are dense and can block as much as 70–90% of solar radiation from reaching the ground. High-elevation trees cannot always reach the thermal treeline, the potential upper range limit set by growing-season temperature. Most high-elevation forests haven’t been subjected to much fire suppression, logging or other human activities, and because trees at these high elevations are in wetter forests, they historically have long return intervals between fires, typically a century or more. In montane landscapes, the latter factors can vary significantly with topography at small spatial scales, potentially. Ask a question. What's this phenomenon ? A. tropical forest D. If climate warming continues in northeastern China, further continuous and substantial increase in tree growth would substantially raise forest productivity in mixed coniferous and broad-leaved forests. Search for an answer or ask Weegy. S. D- Erosion occurs through deflation, and sand that. The valleys are dominated by upper temperate and subalpine forests mainly composed of conifers like Larix species, Abies spectabilis, and some broadleaf. Some scientists propose that increased soil acidity might be the cause. This phenomenon is: Decreased in pH caused by climate change. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. Not every high‐latitude or high‐elevation forest edge is a treeline. Several dendrochronological studies have focused on growth–climate relationships at Pyrenean high-elevation forests (e. The genus presumably evolved during the Plio-Pleistocene uplift of the. Google Scholar Schmidt-Vogt D (1990b) Fire in high altitude forests of the Nepal Himalayas. The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. , 2012). In general, fine roots showed their highest nutrient concentrations. What's this phenomenon ? A. Gen. High-elevation forests only burn about once every 100 to 250 or more years on average. Following 2020's extreme fire season, high-elevation forests in the central Rocky Mountains now are burning more than at any point in the past 2,000 years, according to a new study. Some scientists propose that increased soil acidity might be the cause. com is the easiest and fastest way to get answers to your questions, by providing a mashup of several technologies including an AI-enabled Q&A knowledgebase and integrated chat with live experts. Most of the high altitude wetlands in South Asia, including Nepal, lie within the Hindu Kush Himalayan Region that extends over 3,500 km and covers approximately 3. Some scientists propose that increased soil acidity might be the cause. In southern Colorado high elevation may start around 10,000 ft (3,000 m) above sea level whereas in coastal British Colombia 3,000 ft (1,000 m) would be considered high elevation. com. Some scientists propose that increased soil acidity might be the cause. This phenomenon is: Decreased in pH caused by climate change. Study with Quizlet and memorize flashcards containing terms like Which is one way that topographic maps are different from other maps?, A new mall will be constructed in a large city. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Weegy: Weegy. Forest: Forest County High Point: 1954: Northern Allegheny Plateau: 134: 14: 42. This phenomenon is: Decreased in pH caused by climate change. The new protected area is home also to the charismatic. Some scientists propose that increased soil acidity might be the cause. Correa‐Díaz 1, L. Location: North Central Pennsylvania in Tiadaghton State Forest near the settlement of Slate Run. Latitude, temperature, moisture and elevation define the distribution of various temperate forests and trees. This long view. periodic fires, The biome with high amounts of precipitation, large narrow. Here, we analyse tree-ring-based growth-climate relationships for two dominant tree species along an 800-m elevational. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. The main aim is to relate differences within and between the forests to current theory on the effect of human disturbance on primate. (2010) reported total carbon in the range of 73. s. High-elevation forests only burn about once every 100 to 250 or more years on average. elevation regions B. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. 3. Environmental Science. l corresponds tothe lowest alpine treelin elevation recordee 105 d over the MTP (Shi et al 2019, Singh, 2018). Ringing Rocks Ramble. Ozone depletion . 1 Introduction. Some scientists propose that increased soil acidity might be the cause. Because they are located above 15,000 feet, areas in the Tierra Nevada elevation zone have _____ ecosystems. The Nepal Himalaya is experiencing a higher temperature rise with erratic rainfall and more drought events in recent decades. The Ruffed Grouse (Bonasa umbellus), a small, commonly hunted game bird, inhabits northern boreal forests. Furthermore, warming has changed characteristics of wildfires enabling a median upslope advance of 252 m in high. climate regions D. In montane landscapes, the latter factors can vary significantly with topography at small spatial scales, potentially. Acid rain, which is caused by SO, from combustion mixed with atmospheric water vapor O B. A locked padlock) or means you’ve safely connected to the . The Cumberland Mountains are a mountain range in the southeastern section of the Appalachian Mountains. Like other grouse, they are ground. Proceedings from the Conference on the Ecology and Management of High-Elevation ForestsIn high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. This phenomenon is: Decreased in pH caused by climate change. Clicker. Highest point in Pennsylvania, the 'cradle of forestry' and other little-known facts from our state parks and forests. Print/PDF map. These changing conditions have significant implications for carbon storage, snowpack, and the. distance from the equator. 10 (1): e02568. Whispering Secrets. Vospernik and Nothdurft, 2018) or at high elevation sites (Li et al. Crawford: Czeck Benchmark:. F) plateau. High-elevation forests are important for. A record of stream chemistry in forest watersheds of the Catskill Mountains (New York) has shown increasing NO − 3 concentrations since 1920, apparently in response to. l. Here, the term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. 4 (673) Ringing Rocks County Park. This phenomenon is: Decreased in pH caused by climate change. These are high-altitude valleys in the Himalaya, characterized by upper temperate and subalpine climatic conditions. Some scientists propose that increased soil acidity might be the cause. In colder than standard air temperature. A warming climate, however, has increased the size and severity of fires with significant ecosystem and societal implications. Weegy. History and Extent of Pennsylvania Boreal Forests Pre-settlement Pennsylvania was approximately 90- to 95-percent forested (DeCoster 1995). Martha Kent brought the cactus to Bozeman, most likely from Pennsylvania by wagon. The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. Don't Edit. , 2016; Camarero & Gutiérrez, 2004; Gehrig-Fasel et al. tropical forest D. This phenomenon is: Decreased in pH caused by climate change. Non-native disease-carrying mosquitoes have decimated low elevation populations of native Hawaiian birds, and are now moving into high elevation forests, such as the one shown here. Treelines around the world vary in elevation but are all characterized by having a similar mean July temperature of about 13 deg C (55. 00m a. Wildfires are an integral process in vegetative terrestrial land which shape ecosystem functions. Tech. 7 miles, round trip. ; Schuler, Thomas M. The National Audubon Society reports that deforestation has led to over a fifty percent decline in their population levels over the past forty years. Choose the factors that influence the climate of the U. The Cameron Peak Fire in Colorado in 2020 was the state’s largest fire in its history, burning over 208,000 acres (84,200 hectares) and is a prime example of a high-elevation forest fire. Length: 43 Miles. Pine Creek Gorge, located in Tioga State Forest, is known as the Grand Canyon of Pennsylvania for its dramatic views and steep glacially carved walls. Ozone depletion . These forests are at elevations ranging between 5,000 and 10,000 feet, says Smithsonian. s. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. The elevation at which one habitat changes to another varies across the globe, particularly by latitude. The park is named for Blue Knob, the second highest mountain in Pennsylvania at 3,146 feet (959 m). Red spruce dominates at low elevations [ 327 ]. Soils are wetter than in the other two high-elevation forest communities and the vegetation of the community resembles that of lowland spruce - fir forest. 30 to 137. There are several different types of roosts that serve different purposes—day and night roosts provide habitat. Elevation range of reserve varies from 1800 to 7817 m. High elevation forests are especially susceptible to disturbance and because of the short growing season, take longer to recover than forests at lower elevations (Zhao et al. This phenomenon is: Decreased in pH caused by climate change. Ask a question. 1 The treeline concept. By Jane Qiu on January 27, 2015. Get an answer. The highest amounts of nutrients in both live and dead fine roots were observed in September and the lowest in the month of June and turnover rates of the nutrients in the fine roots also decreased with an increase in elevation. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Rentch, James S. One hypothesis for the lack of coherent responses in growth and resource use efficiency in high-altitude ecosystems is that regional CO 2 and warming effects are secondary to local hydrologic, biogeochemical, and ecological factors (17, 20–23). New answers. Herbaceous plants above treeline are scarce, occurring in densities considerably less than 1 plant/M2. Decreases in pH caused by climate change O C. km. In high -elevation forests in Pennsylvania , ecologists have noticed a serious decline in certain tree species. [ The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. Meanwhile, they found that lower elevation forests reduced their water use on average. B- Erosion occurs as surface water carries sediment and the sediment is deposited near oceans and lakes. Study with Quizlet and memorize flashcards containing terms like Fall lines, A) Adirondacks B) Alleghenies C) Catskills E) Green Mountains G) White Mountains, Glaciers scoured the landscape, grinding the high places and mixing the soil with rocks. Decreased in pH caused by climate change C. . 0 acre (0. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. When density altitude is higher than indicated altitude. Forest ages range from young stands (less than 100 years old) to old-growth stands 1,000 or more. Wildfires in California’s fabled Sierra Nevada mountain range are increasingly burning high-elevation forests, which historically have seldom burned, reports a team of researchers led by the John Muir Institute of the Environment at the University of California, Davis. rugulosa at 3777 m a. grassland B. Clicker. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. , eds. ] Score . The forests were stratified into three altitudinal zones: low-altitude forest (LF), ranging from 900 m a. Fine root nutrient dynamics were calculated for one year in three high elevation forests of Indian central Himalaya. 3. , eds. ©Zack Frank/Shutterstock. In 1994–1995, metal stress in red spruce foliage evidenced by phytochelatin concentrations increased with red spruce damage index in spruce-fir dominated stands in high elevation forests. A. Trees and the insects that eat them wage constant war. Forest Glow - in explore. Proceedings from the conference on the ecology and management of high-elevation forests in the central and southern Appalachian Mountains. The Wieslander survey from the 1930s provides an anachronistically high resolution (minimum mapping unit of 16 ha) and expansive (176,900 km 2). Douglas-fir is also frequently planted on cutover areas within this zone. highland C. The study observes changes in upslope advance in high-elevation forest fires, how climate aridity—and our warming planet—is correlated with these fires, and how biodiversity loss and vegetation conversion factor into these changing conditions. (Kessler and Schmidt-Lebuhn, 2006). rugulosa at 3777 m a. Trahan,2,† Phil Wilkes,3 Tristan Quaife,4 Britton B. Weegy: When a poet wishes to use figurative language, he or she will use words that are both connotative and denotative. and more. The length of the upper border of forests in the mountainous regions of the world is tens of thousands of kilometers and in many regions the open and closed forest lines have shifted (Figure 1. Most high-elevation forests haven’t been subjected to much fire suppression, logging or other human activities, and because trees at these high elevations are in wetter forests, they historically have long return intervals between fires, typically a century or more. l. Acid caused by S*O_{3} combustion mixed with atmospheric water vapor B.