After dealing with an overwhelming pine beetle blight for the past few years, Colorado residents now face what, so far, is a devastating fire season. A modest winter snowpack, combined with a dry spring, has set the stage for lightening and human-induced forest fires. In addition, the presence of so many dead pine trees will surely exacerbate that threat.
Our human-centric view of nature often leads to false conclusions about man's role in the occurrence of "natural disasters." Many are quick to blame fire-suppression policies for both the beetle blight and the wildfires while others see the hand of God, a biblical punishment for the ills of human society . But natural wildfires play a vital role in the maintenance of forest ecosystems, clearing out dead wood, opening the canopy and allowing the seeds of certain trees (lodgepole pines, for example) to germinate. In like manner, pine bark beetles attack stressed or diseased trees and their massive infestations, which probably occur every century or so, restore forests with a diverse assembly of young, healthy trees. While it is an unwelcome sight for residents and tourists, the remnant landscape of dead or burned trees is a necessary stage in the life of a forest; unfortunately, when viewed from the perspective of our brief human life span, it appears all too permanent.
Aspen trees, which spread by suckering and take advantage of clearings in the coniferous forests, will likely be the primary beneficiaries of these "disasters" in the short run. Humans who chose to reside in western forests are among the primary victims, losing pristine scenery if not their homes. Like those who live on barrier islands or along river floodplains, they were taking a chance; most will be philosophical, acknowledging the risk that comes with living in the Colorado mountains and respecting the natural forces that, over the centuries, mold our landscape.
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Rabu, 20 Juni 2012
Minggu, 19 Februari 2012
The Nature of Conifers
Conifers, represented by 200 species in North America and more than 600 worldwide, evolved in the Pennsylvanian Period, some 300 million years ago; indeed, they have colonized our planet twice as long as flowering plants, which appeared in the Jurassic. Many of our modern conifers have graced the planet for 100 million years or more and now include the tallest (California Redwood), largest (Giant Sequoia) and longest-lived (bristlecone pine) trees on Earth.
Characterized by needle-like or lace-patterned leaves, conifers produce male and female cones which, depending on the species, may occur on the same plant. The male cones release a copious amount of pollen which, carried by the wind, fertilizes the female cones; seeds are born on scales of the female cone and are dispersed by birds, red squirrels, chipmunks or by the cone itself when it falls to the ground; in some species, such as lodgepole pines, the heat of wildfire is a crucial step in releasing the seeds. Though most conifers are evergreen, shedding old needles and growing new ones in a patterned sequence, there are deciduous species, including some larches and cypress trees. While true fruits are not produced by conifers, the small females cones of junipers and yews look like globular fruit and are often referred to as berries; robins, solitaires and waxwings are especially fond of these cones.
The resin produced by most conifers, offering protection from insects and disease, increases the flexibility of their branches, making conifers more tolerant of heavy snow while still retaining their photosynthetic needles. This trait, combined with their simplified mode of reproduction, makes conifers more capable of surviving in areas with a short growing season and they thus dominate forests across northern latitudes and at high elevations of mountain ranges. Indeed, through heavily logged for lumber and paper, Earth's vast boreal forests provide a vital carbon sink, helping to keep global warming in check.
Characterized by needle-like or lace-patterned leaves, conifers produce male and female cones which, depending on the species, may occur on the same plant. The male cones release a copious amount of pollen which, carried by the wind, fertilizes the female cones; seeds are born on scales of the female cone and are dispersed by birds, red squirrels, chipmunks or by the cone itself when it falls to the ground; in some species, such as lodgepole pines, the heat of wildfire is a crucial step in releasing the seeds. Though most conifers are evergreen, shedding old needles and growing new ones in a patterned sequence, there are deciduous species, including some larches and cypress trees. While true fruits are not produced by conifers, the small females cones of junipers and yews look like globular fruit and are often referred to as berries; robins, solitaires and waxwings are especially fond of these cones.
The resin produced by most conifers, offering protection from insects and disease, increases the flexibility of their branches, making conifers more tolerant of heavy snow while still retaining their photosynthetic needles. This trait, combined with their simplified mode of reproduction, makes conifers more capable of surviving in areas with a short growing season and they thus dominate forests across northern latitudes and at high elevations of mountain ranges. Indeed, through heavily logged for lumber and paper, Earth's vast boreal forests provide a vital carbon sink, helping to keep global warming in check.
Sabtu, 21 Januari 2012
Along the Myakka
The Myakka River, in southwest Florida, one of only two rivers designated "Wild & Scenic" by the Sunshine State, rises in northern Manatee County and flows southward for 60 miles to Charlotte Harbor. Along the way, it passes through the lakes and marshlands of Myakka River State Park, east of Sarasota, and encounters little human development for much of its course; indeed, Sarasota County has been especially committed to protecting its natural channel and three preserves offer access to southern portions of this ecosystem.
Having enjoyed a week along the Gulf Coast, we decided to head inland and explore the lower Myakka corridor. Jelks Preserve, about two miles south of I-75 on North River Road (via the North Port/Englewood Exit), provides an excellent overview of natural habitats along the river as well as scenic views of the Myakka itself; oak hammocks, festooned with Spanish moss, border slash pine flatwoods, marsh-lined ponds and scrub meadows. Armadillos were abundant along the sandy trails, black vultures and bald eagles soared overhead and American alligators, though unseen on our visit, haunt the shallow pools and wetlands. Myakka River State Forest, about 5 miles south of U.S. 41 via River Road, offers an extensive network of trail loops through these same habitats; it was there that we encountered a massive flock of wintering tree swallows, surely numbering in the thousands, and watched a trio of Florida sandhill cranes drift across the bright blue sky. Finally, Myakka Islands Point, a Sarasota County preserve west of North Port, provides access to pine flatwoods (dominated by slash pine, cabbage palm and saw palmetto) which overlook broad swaths of riverside marsh.
South of these preserves the Myakka becomes increasing brackish as it receives tidal inflow; in concert, the river leaves its meandering, tree-lined corridor and open marshlands stretch across its broad floodplain. Alligators that bask along the River's more northern shores avoid these salty waters but manatees, moving in from the bay, now inhabit the Myakka. As expected, wading birds are abundant across this vibrant tidal zone, roosting in tree islands that rise above the marsh.
Having enjoyed a week along the Gulf Coast, we decided to head inland and explore the lower Myakka corridor. Jelks Preserve, about two miles south of I-75 on North River Road (via the North Port/Englewood Exit), provides an excellent overview of natural habitats along the river as well as scenic views of the Myakka itself; oak hammocks, festooned with Spanish moss, border slash pine flatwoods, marsh-lined ponds and scrub meadows. Armadillos were abundant along the sandy trails, black vultures and bald eagles soared overhead and American alligators, though unseen on our visit, haunt the shallow pools and wetlands. Myakka River State Forest, about 5 miles south of U.S. 41 via River Road, offers an extensive network of trail loops through these same habitats; it was there that we encountered a massive flock of wintering tree swallows, surely numbering in the thousands, and watched a trio of Florida sandhill cranes drift across the bright blue sky. Finally, Myakka Islands Point, a Sarasota County preserve west of North Port, provides access to pine flatwoods (dominated by slash pine, cabbage palm and saw palmetto) which overlook broad swaths of riverside marsh.
South of these preserves the Myakka becomes increasing brackish as it receives tidal inflow; in concert, the river leaves its meandering, tree-lined corridor and open marshlands stretch across its broad floodplain. Alligators that bask along the River's more northern shores avoid these salty waters but manatees, moving in from the bay, now inhabit the Myakka. As expected, wading birds are abundant across this vibrant tidal zone, roosting in tree islands that rise above the marsh.
Senin, 03 Oktober 2011
October Woods
October is, in my opinion, the best month for hiking through forests of the American Heartland. Then again, in my opinion, it's the best month for just about anything.
The cool air, warm sun, colorful vegetation and relatively dry trails offer ideal hiking conditions. While most of our summer birds have departed for the south, winter residents, such as juncos, yellow-rumped warblers and white-throated sparrows, drift down from Canada, joining the cardinals, chickadees, titmice, nuthatches, woodpeckers and other permanant residents. The raucous jabber of blue jays now dominates the birdsong but the yank of the white-breasted nuthatch is perhaps most typical of the autumn woodland.
The seasonal chill also increases the activity of our resident mammals, making them more conspicuous among the colorful trees. The fragrance of fallen walnuts, at times mingled with that nostalgic scent of woodsmoke, drifts through the forest and the sound of acorns, dropping through the canopy, envelops the hiker. For the naturalist, these sights, sounds and smells of autumn are especially inviting and, reluctant to leave the October woods, his pace slows to an amble.
The cool air, warm sun, colorful vegetation and relatively dry trails offer ideal hiking conditions. While most of our summer birds have departed for the south, winter residents, such as juncos, yellow-rumped warblers and white-throated sparrows, drift down from Canada, joining the cardinals, chickadees, titmice, nuthatches, woodpeckers and other permanant residents. The raucous jabber of blue jays now dominates the birdsong but the yank of the white-breasted nuthatch is perhaps most typical of the autumn woodland.
The seasonal chill also increases the activity of our resident mammals, making them more conspicuous among the colorful trees. The fragrance of fallen walnuts, at times mingled with that nostalgic scent of woodsmoke, drifts through the forest and the sound of acorns, dropping through the canopy, envelops the hiker. For the naturalist, these sights, sounds and smells of autumn are especially inviting and, reluctant to leave the October woods, his pace slows to an amble.
Minggu, 24 Juli 2011
Colorado's Beetle Blight
While massive forest fires grab headlines across the globe, the more widespread and insidious destruction of trees by beetle infestation is relatively unknown to the public at large. But foresters, tourism officials, resort owners, utility workers and anyone who drives through the mountains of Colorado are keenly aware of the extensive destruction wrought by the mountain pine beetle.
These beetles are natural residents of pine forests, generally feeding on and reproducing in aging and stressed trees, thereby helping to maintain the health of the ecosystem. However, over the past decade, the population of these voracious insects has exploded, thanks to extensive stands of mature lodgepole pine, partly created by wildfire suppression. Arising in north-central Colorado and spreading southward into the heart of ski-country, the epidemic has turned magnificent green forests into an ugly patchwork of dead and dying trees, broken only by stands of aspen and spruce. Adding fuel to the devastation, a spruce beetle outbreak in southwest Colorado, spawned by wind-fall from powerful storms, threatens to spread northward through the State.
Though the current mountain pine beetle outbreak is the worst in recorded history, such events have occurred on a regular basis (perhaps every 200 year or so) and likely play an important role in producing diversified forest by clearing out extensive stands of mature, lodgepole pine. Some foresters believe that global warming may have played a role in the current blight, stressing trees with periodic drought and eliminating severe winter cold that helps to reduce the beetle population. Whatever the reason for these natural epidemics, there is little we can do to stop them once they take hold; quick containment and preventive spraying may be possible near towns and resorts but the wholesale destruction of pine forests by a prolific beetle has forced humans to concentrate on dealing with the aftermath.
These beetles are natural residents of pine forests, generally feeding on and reproducing in aging and stressed trees, thereby helping to maintain the health of the ecosystem. However, over the past decade, the population of these voracious insects has exploded, thanks to extensive stands of mature lodgepole pine, partly created by wildfire suppression. Arising in north-central Colorado and spreading southward into the heart of ski-country, the epidemic has turned magnificent green forests into an ugly patchwork of dead and dying trees, broken only by stands of aspen and spruce. Adding fuel to the devastation, a spruce beetle outbreak in southwest Colorado, spawned by wind-fall from powerful storms, threatens to spread northward through the State.
Though the current mountain pine beetle outbreak is the worst in recorded history, such events have occurred on a regular basis (perhaps every 200 year or so) and likely play an important role in producing diversified forest by clearing out extensive stands of mature, lodgepole pine. Some foresters believe that global warming may have played a role in the current blight, stressing trees with periodic drought and eliminating severe winter cold that helps to reduce the beetle population. Whatever the reason for these natural epidemics, there is little we can do to stop them once they take hold; quick containment and preventive spraying may be possible near towns and resorts but the wholesale destruction of pine forests by a prolific beetle has forced humans to concentrate on dealing with the aftermath.
Minggu, 26 Juni 2011
Cicada Aftermath
Returning to central Missouri after a brief visit to Florida, we found twigs and clumps of leaves scattered across the lawn; also noticing numerous broken stems in the canopy of some trees (especially the maples and mimosas), we initially assumed that a powerful wind storm had passed through Columbia. On closer inspection, however, we saw grooves on the underside of these terminal branches, indicating that cicadas had produced the damage.
Though their adult life is limited to a week or two, female cicadas can cause significant damage to young trees and shrubs by carving a linear trough along terminal stems in which to lay their eggs. Since tender shoots are favored, young trees are more severely affected and, in some cases, the numerous wounds are fatal. The massive number of periodical cicadas is especially devastating to regional vegetation while the annual cicadas, just now emerging, produce limited damage.
We often ponder how each plant and animal species plays a unique role in nature's delicate balance but uncovering the importance of periodical cicadas, which spend 13 or 17 years beneath the soil followed by 2 weeks of frenzied mating and tree damage, is a challenge indeed. Their mass emergence may play a role in soil aeration, their huge numbers provide a welcome bounty for many birds and mammals and their glut of rotting bodies may be a valuable source of nutrients for growing plants; however, the associated damage to trees makes one wonder if these benefits outweigh their cost to the ecosystem. Then again, cicadas, like all other species, are focused on the survival of their genes, not on the welfare of their natural environment. They may not realize it and we may not like it but, so far, they have been very successful at evading extinction.
Though their adult life is limited to a week or two, female cicadas can cause significant damage to young trees and shrubs by carving a linear trough along terminal stems in which to lay their eggs. Since tender shoots are favored, young trees are more severely affected and, in some cases, the numerous wounds are fatal. The massive number of periodical cicadas is especially devastating to regional vegetation while the annual cicadas, just now emerging, produce limited damage.
We often ponder how each plant and animal species plays a unique role in nature's delicate balance but uncovering the importance of periodical cicadas, which spend 13 or 17 years beneath the soil followed by 2 weeks of frenzied mating and tree damage, is a challenge indeed. Their mass emergence may play a role in soil aeration, their huge numbers provide a welcome bounty for many birds and mammals and their glut of rotting bodies may be a valuable source of nutrients for growing plants; however, the associated damage to trees makes one wonder if these benefits outweigh their cost to the ecosystem. Then again, cicadas, like all other species, are focused on the survival of their genes, not on the welfare of their natural environment. They may not realize it and we may not like it but, so far, they have been very successful at evading extinction.
Senin, 06 Desember 2010
Eastern White Pines
It is during the winter, when the deciduous trees are bare, that we pay most attention to the conifers. But, since I park by pickup beneath a large white pine at our Columbia home, I find it hard to ignore this tree in any season. In spring, its small staminate flowers release a copious amount of yellow pollen which coats the truck; soon thereafter the spongy flowers begin to fall, collecting in the bed or along the base of the windshield. Drops of pine sap leave sticky residue on the hood throughout the year and heaps of yellowing pine needles surround the pickup in mid autumn.
Eastern white pines, the largest conifers in eastern North America, are native to southern Canada, New England, Pennsylvania, and the Great Lake States, extending southward along the Appalachian chain. Widely planted as ornamentals, these stately trees were once used for sail masts and are now harvested for lumber or used as Christmas trees. Often growing up to 100 feet tall and possessing a girth that may exceed 10-15 feet, some white pines in virgin stands exceed 200 feet in height. Those that escape browsing, disease or human harvesting may live for 250 years and a few specimens are known to be nearly 500 years old.
Due to their relatively long needles (bundled in groups of 5) and the open spacing of their limbs, eastern white pines have an airy appearance. Their 6-inch cones peak in number every 3-5 years and bear seeds that are favored by tree squirrels, pine siskins, nuthatches, crossbills and a variety of finches. Moderately resistant to fire, white pines often form extensive stands in undisturbed areas, overgrowing and shading out their smaller deciduous neighbors. My pickup truck and I can certainly vouch for their rapid growth and prolific nature!
Eastern white pines, the largest conifers in eastern North America, are native to southern Canada, New England, Pennsylvania, and the Great Lake States, extending southward along the Appalachian chain. Widely planted as ornamentals, these stately trees were once used for sail masts and are now harvested for lumber or used as Christmas trees. Often growing up to 100 feet tall and possessing a girth that may exceed 10-15 feet, some white pines in virgin stands exceed 200 feet in height. Those that escape browsing, disease or human harvesting may live for 250 years and a few specimens are known to be nearly 500 years old.
Due to their relatively long needles (bundled in groups of 5) and the open spacing of their limbs, eastern white pines have an airy appearance. Their 6-inch cones peak in number every 3-5 years and bear seeds that are favored by tree squirrels, pine siskins, nuthatches, crossbills and a variety of finches. Moderately resistant to fire, white pines often form extensive stands in undisturbed areas, overgrowing and shading out their smaller deciduous neighbors. My pickup truck and I can certainly vouch for their rapid growth and prolific nature!
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