Trees. (For the Envirothon) By Patrick Sopko
Eastern Hemlock LEAVES Evergreen needles occur singly, appearing 2-ranked on twigs, flattened, about 1/2" long, dark green and glossy, light green with 2 white lines below TWIGS Slender, tough, yellowish brown to grayish brown. Buds egg shaped, 1/16" long, reddish brown. FRUIT Cones 3/4" long, egg-shaped, hanging singly from the tips of twigs. Under each scale are 2 small, winged seeds .BARK Flaky on young trees, gray brown to red brown, thick and roughly grooved when older.
Eastern Hemlock Info • Drought is probably the most serious damaging agent to eastern hemlock, especially during the seedling stage. Winter drying caused by excessive transpiration on warm, windy days has caused severe needle injury. • In later stages of stand development, heavy cuttings predispose trees to windthrow because of their shallow rooting habit. Older trees are susceptible to radial stress cracks and ring shake, particularly in partially cut stands (19). Eastern hemlock is sensitive to salt spray or drift and sulfur fumes and is one of the species most often struck by lightning (16,25).
Damaging Agents • Damaging Agents- Seeds of eastern hemlock are sensitive to damage from several molds, particularly Botrytis spp., that reduce or delay germination (23). Some molds are borne internally while others colonize the seeds during germination. In one study, the fungus Aureobasidumpullulans was isolated from 73 percent of the seedcoats. In another test this mold was isolated twice from the embryonic tissue and 13 times from the seedcoat. Generally, molds are less injurious than desiccation during the germination and seedling stages. • The most damaging agents to young seedlings, other than desiccation, are damping-off fungi and root rots (16). Pythium spp. and Rhizoctonia spp. flourish in wet, poorly drained soils and in well-drained soils, respectively, and are common on eastern hemlock. At least three root rots- Cylindrocladiumscoparium, Rhizinaundulata (common on burn areas), and Fusariummoniliforme- are common on eastern hemlock. F. moniliforme has been isolated from embryonic tissue and seedcoats as well as in the soil (16,23).
Continued…. • Several diseases affect the needles and twigs of eastern hemlock. The rust caused by Melampsorafarlowii is one of the most damaging. It causes shoot blight and curls and attacks the cone often resulting in cone abortion. Three rusts caused by M. abietiscanadensis, Pucciniastrumhydrangeae, and P. vaccinii spp. affect only the needles. Single needle browning throughout the crown is caused by Fabrellatsugae. Lower foliage in very wet and shady areas often has a grayish mat appearance on both the needles and twigs caused by Roselliniaherpotrichioides. Dimerosporiumtsugae occasionally forms a black, sooty growth on the needles. • Living heartwood of eastern hemlock is attacked by Tyromyces borealis, particularly in the northeast, leaving white flecks in the wood. Pholiotaadiposa is fairly common in the Lake States and causes a cavity along the pith axis. Other rots are the trunk rot caused by Haematostereumsanguinolentum; a brown, red ring rot caused by Phellinuspini; and a red heart rot caused by P. robustus. The red-varnish-topped fungus, Ganodermatsugae, is the most common decayer of stumps and old logs
Continued More… • Numerous fungi are associated with the root system but rarely develop conks or kill trees. The most common are the shoestring fungus, Armillariamellea, and the velvet top fungi, Phaeolusschweinitzii, Tyromycesbalsameus, and Heterobasidionannosum. At least two mycorrhiza are known to occur on the roots (16). • Although at least 24 insects attack eastern hemlock, few are economically important. The most important is the hemlock borer, Melanophilafulvoguttata, which attacks weakened trees. Symptoms usually consist of woodpecker-like holes in the bark, galleries filled with dark excrement, and yellowing shoot tips (27). Spruce budworm, Choristoneurafumiferana, defoliates and kills hemlock after defoliating all the balsam fir in the stand.
Continued Even More… • The hemlock looper, Lambdinafiscellariafiscellaria, devours part of the needle after which the remainder turns brown. In nurseries, white grubs of the strawberry root weevil, Otiorhynchusovatus, consume the roots, and larvae of the black vine weevil, O. sulcatus, feed on the needles (40). In the eastern States the hemlock scale, Abgrallaspisithacae, damages young shade trees, and the gypsy moth, Lymantriadispar, kills understory trees. • Numerous animals feed on eastern hemlock and often cause serious damage, marked loss of vigor, or even death. White-tailed deer readily browse this species although it has been ranked seventh in winter food preference. In some regions, patches of regeneration have been eliminated following heavy browsing in years when deer populations are high. Although deer have been blamed for the absence of eastern hemlock in many localities, no regeneration occurred under similar conditions in fenced areas; thus, overstory-site-temperature requirements are presumably more critical (2,6,8).
Continued even more further... • Snowshoe hares and New England cottontails frequently browse eastern hemlock. Mice, voles, squirrels, and other rodents also feed on seeds and small seedlings both under natural stands and in nurseries (1). Porcupines occasionally gnaw the bark on larger trees causing serious wounds and top-kill (4). Sapsuckers have been associated with ring shake in some areas (19,21). • Small eastern hemlock trees are highly susceptible to wildfire but prescribed burns are beneficial for securing natural regeneration. The thick bark of older trees is resistant to light burns but saplings are usually destroyed. Root injury often occurs from high intensity fires because of heavy litter accumulation.
Management Practices • One of the concerns of forest managers is • predicting when stands infested with hemlock • woolly adelgid will experience damage and • mortality. Until effective biological controls, • tree resistance, or practical chemical pesticides • can be developed (see the section on controlling • hemlock woolly adelgid), managers should • anticipate damage to hemlock stands within • several years of the initial infestation. • Fortunately, steps can be taken to • speed recovery and minimize the • impact that the loss of hemlock • will have on ecosystem functions • and esthetic values. To avoid crisis • management, these steps should be • initiated before the onset of widespread • hemlock decline and mortality. As • noted above, there are several years • between initial infestation and marked • stand mortality. Thus, there is usually • ample time for thorough planning.
Tree Parts and Functions • Background Information: • Crown—part of the tree that consists of the leaves and the branches at the top of a tree. • Leaves—food factories of the tree. The leaves contain chlorophyll which gives leaves their green color and is responsible for photosynthesis. During photosynthesis, leaves use energy from the sun to convert carbon dioxide from the atmosphere and water from the soil into sugar and oxygen. The sugar (which is the tree’s food) is either used or stored in the branches, in the trunk, or in the roots. The oxygen is released into the atmosphere.
Continued… • Trunk (Stem)—supports the leaves and the branches of the tree and also contains the xylem, the cambium, the phloem, and the heartwood. • Heartwood—inner core of dead wood that supports the tree. As a tree grows, older xylem cells in the center of the tree become inactive and die, forming the heartwood. • Sapwood (Xylem)—the youngest layer of wood that transports water and minerals up the tree to the branches and the leaves. • Cambium—the part growing layer that is only one to two cells thick. It makes new cells during the growing season that eventually become part of the phloem, of the xylem, or more cambium. The cambium is what makes the trunk, branches, and roots grow larger in diameter.
Continued more… • Inner Bark (Phloem)—carries nutrients and sugar from leaves down the tree to its branches, trunk, and roots. • Outer Bark—protects the tree from injury, disease, insects, and weather. • Taproot—long main root that anchors the tree and absorbs water and nutrients from deep in the soil. It helps to support the tree. (Not all types of trees have a taproot.) • Lateral Roots—underground roots that get smaller and smaller. They take in water and nutrients and help to support the tree. (All trees have lateral roots.) • Annual Tree Rings—records the tree’s age. Every year a tree grows a little more and a new tree ring is made.
Photosynthesis. • Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar. This process occurs in plants and some algae (Kingdom Protista). Plants need only light energy, CO2, and H2O to make sugar. The process of photosynthesis takes place in the chloroplasts, specifically using chlorophyll, the green pigment involved in photosynthesis. • The overall chemical reaction involved in photosynthesis is: 6CO2 + 6H2O (+ light energy) C6H12O6 + 6O2. This is the source of the O2 we breathe, and thus, a significant factor in the concerns about deforestation. • Photosynthesis takes place primarily in plant leaves, and little to none occurs in stems, etc. The parts of a typical leaf include the upper and lower epidermis, the mesophyll, the vascular bundle(s) (veins), and the stomates. The upper and lower epidermal cells do not have chloroplasts, thus photosynthesis does not occur there. They serve primarily as protection for the rest of the leaf. The stomates are holes which occur primarily in the lower epidermis and are for air exchange: they let CO2 in and O2 out. The vascular bundles or veins in a leaf are part of the plant's transportation system, moving water and nutrients around the plant as needed. The mesophyll cells have chloroplasts and this is where photosynthesis occurs.
Photosynthesis Continued… • Chlorophyll looks green because it absorbs red and blue light, making these colors unavailable to be seen by our eyes. It is the green light which is NOT absorbed that finally reaches our eyes, making chlorophyll appear green. However, it is the energy from the red and blue light that are absorbed that is, thereby, able to be used to do photosynthesis. The green light we can see is not/cannot be absorbed by the plant, and thus cannot be used to do photosynthesis. • The overall chemical reaction involved in photosynthesis is: 6CO2 + 6H2O (+ light energy) C6H12O6 + 6O2. This is the source of the O2 we breathe, and thus, a significant factor in the concerns about deforestation.
Conifers and Angiosperms. • Conifers: Have seeds on their needles and seeds • Angiosperms: Have reproductive organisms inside of them. They are usually flowering plants.
Deciduous Trees • Deciduous trees have their leaves fall off in the winter and bear flowers or fruits, as opposed to conifers, which have cones and needles and do not lose their needles.
Benefits of Forests. • Forests give habitat to the wildlife and provide food for them. The plants in the forests give us oxygen. They are also very supercilious to walk in.
Trees By their leaves. • Red Maple Shagbark Hickory • Red Oak American Beech
More leaves • White Oak Sassafras Tulip Poplar • Large Tooth Aspen Black Birch
More leaves White Pine Hemlock Pitch Pine Black Spruce Norway Spruce
More Leaves • Virginia Pines • Red Pine
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