High-elevation pines, including whitebark pine, limber pine, and bristlecone pine, can be found up and down the full range of the Rocky Mountains. These are high-altitude valleys in the Himalaya, characterized by upper temperate and subalpine climatic conditions. 208,000 acres (84,200 hectares) and is a prime example of a high-elevation forest fire. Because they are located above 15,000 feet, areas in the Tierra Nevada elevation zone have _____ ecosystems. 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 University of Montana. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. In high elevation forests in the Southern Rocky Mountains, North America, areas that are dominated by a single tree species are often adjacent to areas dominated by another tree species. 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. 8-mile loop trail near Upper Black Eddy, Pennsylvania. l. High-altitude forests cover 16 million hectares (40 million acres) of land in Africa, primarily concentrated in the Democratic Republic of Congo, but about 5% has already disappeared since the. Whats the phenomenon? A. 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. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. User: Because they are located above 15,000 feet, areas in the Tierra Nevada elevation zone have _____ ecosystems. The valleys are dominated by upper temperate and subalpine forests mainly composed of conifers like Larix species, Abies spectabilis, and some broadleaf. elevation regions B. S. In high-elevation forests in. Crawford: Czeck Benchmark:. , 2019). Contour lines show the elevation above sea level at a given point on your map. In: Rentch, James S. Acid caused by S*O_{3} combustion mixed with atmospheric water vapor B. tropical forest D. The study, published today in the journal Nature Communications, found that white pine blister rust disease expanded its range into higher-elevation forests in the southern Sierra Nevada between. MISSOULA – 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 University of Montana study recently published in the Proceedings of the National Academy of Sciences. Little brown bats are not territorial—they live in colonies numbering in the hundreds of thousands of individuals. S. This study was carried out in two high-elevation forest sites in the Chilean Altiplano, one of P. This community occurs around heath woodlands and fens in high-elevation valleys in the White Mountains and the North Country. Contour Interval. grassland B. In high -elevation forests in Pennsylvania , ecologists have noticed a serious decline in certain tree species. S. s. Some scientists propose that increased soil acidity might be the cause. Based on above finding, it is concluded that overall magnitude of anthropogenic pressure was significant in the area. High-elevation forests are important for. Some scientists propose that increased soil acidity might be the cause. 2) is a continental–dry mountain climate with an average annual precipitation sum between ≈700 and 1400 mm (top of the mountains). F) plateau. The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. Some scientists propose that increased soil acidity might be the cause. elevation regions B. This phenomenon is: Decreased in pH caused by climate change. Colonies aggregate at nesting sites called roosts. 5 million sq. Mercury contamination B. Tree growth in high-elevation forests may increase as a result of increasing temperatures and CO2 concentrations in the atmosphere (Ca). Polylepis (Rosaceae: Sanguisorbeae) forests are distributed across the Central Andes between elevations of 3500 to 5200 m a. Monitoring. 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. Here, we examine past changes in forest composition in Pacific Canada using a paleoecological approach and investigate the role of past changes in climate and differences in species traits in changing forest. grassland B. and high elevation spruce-fir forests of the south western United States have focused on classifi cation and silviculture (e. 3 km 2) followed by kharsu oak (1461. Geoecol Res 6. Ask a question. elevation regions B. This phenomenon is: Decreased in pH caused by climate change. 36 °C by 100 m) and aspect, while the aspect was relevant for RH. 1999). Unlike Sibree’s dwarf lemurs, C. Red spruce dominates at low elevations [ 327 ]. g. Connotative Weegy: Connotative definitions are. Mt. Forest: Forest County High Point: 1954: Northern Allegheny Plateau: 134: 14: 42. Particularly note the patterns of forestland ownership, area of forests,. This community occurs around heath woodlands and fens in high-elevation valleys in the White Mountains and the North Country. Some scientists propose that increased soil acidity might be the cause. The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Clicker. Most Pennsylvania forests are now in age classes between 60 and 120 years, with the largest 10-year classes in the 81- to 100-year range (Jenkins et al. The phenomenon is: Acid rain, which is caused by SO2 from combustion mixed with atmospheric water vapor. Altitude is a primary factor, which gives a possibility of finding common features in the diversity of highlands. l. INTRODUCTION. Acid rain, which is caused by SO, from combustion mixed with atmospheric water vapor O B. 0% of the total area and open regions comprise 8. Get an answer. s. elevation. Length 0. in high elevation forests n Pennsylvania, ecologists have noticed a serious decline in certain tree species. These high-elevation forests share several charac-teristics, including high snowpack retention, low species diversity, low evapotrans-piration and climatic water deficit, longer and more variable fire return intervals, and high sensitivity to changes in climate. 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. Little brown bats also live in high-elevation forests in Mexico. P. Pennsylvania Natural Heritage Program information for the conservation of biodiversity WILD HERITAGE NEWS Summer 2022 Most people picture massive, towering trees when they think of an old growth forest, and they usually aren’t thinking of Pennsylvania. This phenomenon is: Decreased in pH caused by climate change. 1996, Villard et al. Gen. Book County High Points by Andy Martin; list compiled 1993 by Andy Martin, reviewed by Michael Schwartz. New Hampshire. grassland B. Tech. Proceedings from the conference on the ecology and management of high-elevation forests in the central and southern Appalachian Mountains. Weegy: An ecologist is a scientist who studies how animals and plants interact with their environment. Some scientists propose that increased soil acidity might be the cause. Some scientists propose that increased soil acidity might be the cause. When density altitude is higher than indicated altitude. However, instrumental records of climate change are limited in high-altitude forests (Correa-Díaz et al. (Kessler and Schmidt-Lebuhn, 2006). Location: North Central Pennsylvania in Tiadaghton State Forest near the settlement of Slate Run. Some scientists. 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. grassland B. , 2008), climate warming having been found to reduce sensitivity of recent tree-growth to temperature at high northern latitudes and affect tree survival (Briffa et al. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. A high-elevation balsam fir forest community typically occurs between about 3,500 to 4,500 feet, and locally higher or lower depending on site conditions such as topography and degree of exposure. Climate warming is an undoubted fact (IPCC 2007, 2014), and the most rapid warming rates have been observed at high altitudes (Schickhoff et al. The timber era of the late 1800s and early 1900s (as late as 1942) destroyed most of the boreal forest on a large. 3. , eds. Ozone depletion . In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Search for more papers by this author. com is an AI-enabled chat service that observes all of the online support interactions between your call center representatives and customers. Montane forests Waimea Canyon, Hawaii, is known for its montane vegetation. feeling. 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. 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. Denali is also the highest point in North America. Southwestern US mountain ecosystems contain a variety of vegetation communities organized along an. Prospect Street, Fort Collins, Colorado. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. 2,000 to 3,000 feet. Some scientists propose that increased soil acidity might be the cause. In high-elevation forests in Pennsylvania, ecologists have noticed a serious. The work focused on forest fires larger than 405 hectares that occurred between 1984 and 2017. The tallest redwood in the world is called Hyperion, standing at an incredible 380 feet. Clicker. 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. l. 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. Some scientists propose that increased soil acidity might be the cause. grassland B. Mercury. 50 °C ± 0. In high-elevation. Some scientists propose that increased soil acidity might. Despite the importance of forests in PA, many forests have become degraded due to past timber harvesting practices that have mainly removed the largest and most valuable trees from. This phenomenon is: Decreased in pH caused by climate change. Desai,7 Jose Negron6 and Russell K. Score 1A. The impact of climate variability on forests New York:. Some scientists propose that increased soil acidity might be the cause. Ponderosa pine (Pinus ponderosa), also called western yellow pine, is one of the most widely distributed pines in western North America. Increasing minimum temperatures is one factor attributed to northward range expansion of the mountain pine beetle in Canada. 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. com is an AI-enabled chat service that observes all of the online support interactions between your call center representatives and customers. 7% and 61. A. Search for an answer or ask Weegy. Score 1 User: The ring of fire on the map above is a. Section snippets Polylepis tarapacana: The tree growing at the highest elevation in the world. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. A) delta. Some scientists propose that increased soil acidity might be the cause. 3. [ ] User: _____ definitions are made up of the set of associations implied by a word in addition to its literal meaning. The Nepal Himalaya is experiencing a higher temperature rise with erratic rainfall and more drought events in recent decades. [ This phenomenon is: Decreased in pH caused by climate change. Large, severe fires in the West followed by increasing drought conditions as the planet warms are leading to lower tree densities and increased patchiness in high-elevation forests, according to a new study. economic region 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. Himalayan mountain forests have been a potential candidate for the investigation of perturbations due to the complex geography in which they sustain and the sensitivity of the species toward human disturbance and climate change. Weegy. 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. Black lines are fitted predictions from regression models from 768 locations within the White Mountain National Forest from 1993 to 2009. High altitude forest sensitivity to the recent warming: a tree-ring analysis of conifers from western Himalaya, India. 3. The northern hardwood forest occupies the northern third of the state and extends south at high elevations along the Allegheny Front. However, while the significant increases in overall density experienced in these forests over the last few decades (Dolanc et al. Geographers recognize a number of factors that affect a region’s climate: latitude. located at its lower elevation margin (18°24′S and 69°30′W) and the other of P. Warming temperatures play a role, facilitating mountain pine beetle activity at higher elevations and for longer time. S. R. High-elevation forests only burn about once every 100 to 250 or more years on average. Their highest peak, with an elevation of 4,223 feet (1,287 m) above mean. 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. , and the high-altitude forest (HF) ranging from 2500 m a. The San Francisco Peaks/Dook’o’oosłííd in northern Arizona rise to 3851 m elevation with slopes that span many of the major forest types of the southwestern US mountains. Rep. Explanation: The phenomenon that causes a serious decline in certain tree species in high-elevation forests in Pennsylvania is acid rain. The park, nearly surrounded by Loyalsock State Forest, is in the Loyalsock Creek valley on Pennsylvania Route 154 in Forks and Shrewsbury Townships southeast of the borough of Forksville. political regions C. All three forest communities were more efficient in nutrient-use than several broad leaf forest communities at 300 to 2200 m altitude in the central Himalaya (42-79 g. While mountain pine beetle is a native species and has historically had periodic outbreaks, the recent epidemics in high-elevation western forests are considered unprecedented in duration and magnitude over the past 200 years. This image was generated by NOAA from digital data bases of land and. periodic fires, The biome with high amounts of precipitation, large narrow. Some scientists propose that increased soil acidity might be the cause. D. Forest trees exhibit a large variation in basal area increment, which depends on tree specific factors, inter-tree relations and the environment. ] Score . In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. A. 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. It covers an area of about 61,500 square miles (159,000 km 2) in:. Rating. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. grassland B. S. Weegy: Weegy. 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. Forest Glow - in explore. l. Forest biomass is an important component of terrestrial carbon pools. 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. Some scientists propose that increased soil acidity might. Treelines around the world vary in elevation but are all characterized by having a similar mean July temperature of about 13 deg C (55. , 2009) which exert dominant control over forest productivity and tree water status (Körner, 2017; Maxwell et al. Forests in the mountains are mostly dominated by Pacific silver fir and mountain or western hemlock. The area corresponds to the “Abies amabilis zone” of Franklin and Dyrness (1973), whichA. Weegy: In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Some scientists propose that increased soil acidity might be the cause. Martha Kent brought the cactus to Bozeman, most likely from Pennsylvania by wagon. 0 acre (0. What's this phenomenon? O A. Some scientists propose that increased soil acidity might be the cause. Acid rain, which is caused by SO2 from combustion mixed with. 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. , 2016; Camarero & Gutiérrez, 2004; Gehrig-Fasel et al. 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. Rating. The tr 107 ees at high elevations of MTP are almost all conifers, mainly Abies 108Studies have shown that many lower-elevation forests on the West Coast of the United States were experiencing a “deficit” in fire activity compared with historical patterns, partly because of. 2013). 1990). Weegy: In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. with fewer old forests. Its deepest point is 1,450 feet below the rim. 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. 008) of elevation was observed on the forest structural variables, biomass and carbon stock. From the preceding analysis, it is evident that the average elevation of treeline in the Western Himalaya is around 3615 m asl, but trees are recorded up to 4200 m. leucopodia is a cosmopolitan species that can be found on different substrates at lower elevations (Tran et al. Montane forests Waimea Canyon, Hawaii, is known for its montane vegetation. Above about 4,500 feet (approx. In this study, we assessed patterns of structure and tree species. 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. and R. This phenomenon is: Decreased in pH caused by climate change. Some scientists propose that increased soil acidity might be the. 3. Decreases in caused by climate change D. Introduction The concept of fire severity, the effects of a fire on biota, is distressingly qualitative (Johnson and Miya-We quantified total Hg deposition over a two year period at 24 forest sites at Whiteface Mountain, NY, USA that ranged from 450-1450 m above sea level and covered three distinct forest types. Above: Mountain pine beetle and white pine blister rust have heavily impacted this whitebark pine forest in the Mt. There are several different types of roosts that serve different purposes—day and night roosts provide habitat. Due to the climate that comes with their elevation, the highest areas of Southern Appalachia are home to plant. New answers. Yet they experienced the highest rate of increase in fire activity in the. government officially recognized the name of the mountain as “Mount McKinley” (named. B) Denver. New methods have opened research. The fire. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. . Strong interannual links between aridity and. Since acquiring this property, The Nature Conservancy has developed a forestry management plan to improve the ecological conditions of the land to help. l. 3. The primary objectives of this study were to (1) measure N input, uptake, internal generation and export; (2) quantify N pools in biomass and soils in a high-elevation forest in the Adirondacks of New York; and (3) assess the relative importance of atmospheric deposition of N compounds in N cycling. Balsam fir dominates, although heartleaf birch and red spruce may be present. Monson1,8 Abstract Amid a worldwide increase in tree mortality, mountain pine beetles. Further up the slope at an elevation of 4930 m, the junipers are gnarled and multi-stemmed, and carry more than 30% deadwood. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. Chase some more exceptional mountaintop views and climb through rhododendron blooms by the millions on the Craggy Gardens Trail. rugulosa at 3777 m a. User: in high elevation forests in pennsylvania ecologists have noticed a serious decline in certain tree species some scientists (More) In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. weegy;. chaparralPine Creek Gorge- “Pennsylvania Grand Canyon”. New answers. HUBBARD,1 PAUL R. Some scientists propose that increased soil acidity might be the cause. The Hindu Kush Himalaya (HKH) has experienced the most rapid climate warming in. These changing conditions have significant implications for carbon storage, snowpack, and the. D) Georgia. Some scientists propose that increased soil acidity might be the cause. Book County High Points by Andy Martin; list compiled 1993 by Andy Martin, reviewed by Michael Schwartz. S. Some scientists propose that increased soil acidity might be the cause. Here, a four-year litterbag decomposition experiment along an elevation gradient (3000, 3300, 3600 m) was conducted in an Abies faxoniana Rehd. As such, more than 31,000 square miles of high-elevation forests — or roughly 11 percent of forest cover in the western U. The Appalachian Mountains, [b] often called the Appalachians, are a mountain range in eastern to northeastern North America. Mercury. Some scientists propose that increased soil acidity might be the cause. Some scientists propose that increased soil acidity might be the cause. In the coastal fog belt, Douglas-fir is rare and Sitka spruce becomes abundant. Blank 1: dry, drought-deciduous, or seasonal. 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. , the mid-altitude forest (MF), ranging from 1700 m a. tropical forest D. This phenomenon is: Decreased in pH caused by climate change. Tech. 8 miElevation gain 118 ftRoute type Loop. Get an answer. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. A- Waves cause erosion along coastlines and deposit sand away from the shore. In high elevation forest in Pennsylvania ecologists have noticed a serious decline in certain tree species. F. This phenomenon is: Decreased in pH caused by climate change. Because they are located above 15,000 feet, areas in the Tierra Nevada elevation zone have __________ ecosystems. 2,000 to 3,000 feet. Together, these factors control the range of temperatures and the amount of rain and/or snow each region receives. In high-elevation forests in Pennsylvania, ecologists have noticed a serious decline in certain tree species. rugulosa at 3777 m a. tropical forest D. Linking Remote Sensing and Dendrochronology to Quantify Climate‐Induced Shifts in High‐ Elevation Forests Over Space and Time A. 1 The treeline concept. User: In high elevation forest in Pennsylvania ecologist have noticed a serious decline in certain tree species. Most Pennsylvania forests are now in age classes between 60 and 120 years, with the largest 10-year classes in the 81- to 100-year range (Jenkins et al. Print/PDF map. Most of the forests are dense and can block as much as 70–90% of solar radiation from reaching the ground. higher than the actual altitude above sea level. A. Rating. A. 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. s. Mount Davis is the highest point in Pennsylvania. HOOD,2 BANNING J. g. 1). For almost a hundred years, the U. yr(-1)). Elevation range of reserve varies from 1800 to 7817 m. “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. 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. Acid rain is caused by the combination of sulfur dioxide (SO₂) from combustion and. The trail winds and weaves through a lush forest dense with rhododendron, hemlock, and fir, and climbs to 180-degree views of Chimney Tops and nearby Mt LeConte. Rocky Mountain’s sixty mountain peaks over 12,000 feet high provide world attention-grabbing scenery. High-elevation forests only burn about once every 100 to 250 or more years on average. The park is named for Blue Knob, the second highest mountain in Pennsylvania at 3,146 feet (959 m). A locked padlock) or means you’ve safely connected to the . As climate warms, bark beetles march on high-elevation forests. It was used by travelers in the highlands, but was also used in ritual practices to endure long nights of dancing. Hough, A. At 5,729 feet, Mt. ; Schuler, Thomas M. This chapter provides an overview of studies conducted at treelines of the Nepal Himalaya. tropical forest D. , 1998). highland C. Background Previous studies have shown that plants often have species-specific effects on soil properties. Acid rain, which is caused by SO, from combustion mixed with atmospheric water vapor O B. The high-elevation open-canopy northern red oak stands under investiga-High-elevation forests are experiencing high rates of warming, in combination with CO2 rise and (sometimes) drying trends. Why are business owners most likely viewing a topography map before construction?, Winston studies a topography map that shows camping and hiking areas. The general definition used is one followed by the US Geological Survey and the Geologic. Forest types and human impact. chaparralfir-hemlock, these high-elevation forests contain substantial amounts of Douglas-fir, both as stands and as scattered trees or groups intermingled with other species. highland C. The study, published last month in Ecosphere, is one of the first to document the effects of bark beetle kill on high elevation forests’ recovery from wildfire. D- Erosion occurs through deflation, and sand that. Ruffed Grouse grow to about the size of a chicken. 3. Decreases in pH caused by climate change O C. located at its lower elevation margin (18°24′S and 69°30′W) and the other of P. tropical forest D. Some scientists propose that increased acidity might be. The. , 2011) (Fig. Wildfires are an integral process in vegetative terrestrial land which shape ecosystem functions. Coal seams are extracted from a mountain by removing the land, or overburden, above the seams. The field of geography relies on many different types of maps in order to study the features of the earth. (b) Polar regions receive less solar energy per unit of surface area. crossleyi is also found at low, middle, and high altitude forests, from northern to southern Madagascar, including sites along the eastern edge of the central plateau (Blanco et al. Some scientists propose that increased soil acidity might be the cause. This phenomenon is: Decreased in pH caused by climate change. [ 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. Therefore, the combination of dendrochronology and NDVI is widely used to study. The elevation at which one habitat changes to another varies across the globe, particularly by latitude. This phenomenon is: Decreased in pH caused by climate change. s. — could be at risk this year and in future wildfire seasons. To date high elevation forests in the Sierra Nevada have not suffered the catastrophic. A large number of families and genera of trees and shrubs are represented in these forests (Table 1. 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. In montane landscapes, the latter factors can vary significantly with topography at small spatial scales, potentially.