September 3, 2015
January 30, 2015
Winter is a great time to go for a walk and explore the form of trees. Without leaves on deciduous trees you can see the beautiful structure of the tree.
Tree identification requires a little detective work. In the winter months, identifying trees takes a bit more scrutinizing. On deciduous tree since there are no leaves, which are usually the easiest way to identify trees – it’s best to study the branching, buds and twigs and bark.
All trees have either opposite or alternate branching. Alternate branching means that the twigs and buds grow off a main branch one at a time. Opposite branching is when twigs and buds grow off a main branch in pairs.
Ashes, dogwoods and maples are examples of opposite branching. Examples of alternate branching would be birches, sycamores and tulip trees.
Opposite Branching Alternate Branching
The shape, size, color and texture of the buds are never the same in species. Buds bloom into flowers and leaves. Flower buds form in various places and are often much larger than leaf buds. Leaves form as either terminal buds –found at the ends of twigs, or lateral buds – along the sides of twigs. Most buds have protective scales that enclose the leaf tissue. If no scales exist, the buds are considered naked. The number and arrangement of the buds on the twigs are also important.
Those who are more experienced when it comes to identifying trees may find the answers in the bark. While the bark of a tree changes as it matures and varies by geographical region or growing conditions, it can be an easy way to determine the species of the tree. All tree bark has a difference in color, thickness, texture and pattern. Some species tend to peel its bark. For example, shagbark hickory peels vertically in large, thick, curving strips while the paper birch peels horizontally in large strips.
September 24, 2014
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March 7, 2014 By Joe Schwartz
ITHACA, N.Y. – By literally looking below the surface and digging up the dirt, Cornell researchers have discovered that a burgeoning deer population forever alters the progression of a forest’s natural future by creating environmental havoc in the soil and disrupting the soil’s natural seed banks.
The study, “Deer Browsing Delays Succession by Altering Aboveground Vegetation and Below g ound Seed Banks,” was published online March 7 in PLOS ONE.
“Deer are slowing down forest succession or natural establishment. In fact, the deer are preventing forests from establishing,” says Anurag Agrawal, Cornell professor of ecology and evolutionary biology, a co-author on the paper.
Deer typically prefer to eat native, woody plants and rebuff invasive species. The study showed that when deer consume native plants, the non-native species are left to flourish, dropping their seeds in the soil.
As forests normally mature, their grasses give way to herbs and shrubs, and then new trees eventually take root. Expanding deer populations in the Northeast, however, stall forest development and promote the growth of thorny thickets of buckthorn, viburnum and multiflora rose bushes. If deer leave the forests alone, such trees as cottonwood, locust and sumac can sprout and grow unimpeded.
The researchers found that the impacts of deer grazing on vegetation were severe and resulted in bare soil and reduced plant biomass, less recruitment of woody species and relatively fewer native species. And the deer’s negative impact on seed banks resulted in significantly decreased overall species richness and relatively more short-lived species of both annual and biennial plants.
Co-author Antonio DiTommaso, Cornell associate professor of weed ecology and management, and research technician Scott Morris gathered soil cores – from both within and outside of fenced “deer exclosures” – and germinated the seed. They found the soil cores from outside of the exclosures contained many more seeds from non-native species.
Deer select forests for their trees but in doing so disrupt forest system growth trajectories, concludes the study.
“It’s obvious that the deer are affecting the above-ground species, but it’s like an iceberg. There are major effects below the soil surface. We are seeing a divergence of seeds contained within the soil from what should be there,” says DiTommaso. “We are not seeing the seeds of woody plants. Instead, we’re seeing an escalation of non-native seed and the virtual elimination of woody plant seeds.”
The multiyear study was conducted on Cornell land near Freese Road in Ithaca, where the deer density is about 39 animals per square kilometer – about 10 times greater than it was before European settlement in the late 1700s.