Another problem associated with deciduous forests is the introduction of non-native plant and animal species because it upsets the balance of the forest ecosystem. Non-natives may compete for food and habitat space, possibly threatening the native species.
Although these threats may be worrisome, there are many things that you can do to help protect this unique biome. First of all, you can recycle. Trees are used to make the paper for paper bags, newspapers, printer paper, and many more products we use each day. If you recycle used paper, and make the effort to buy recycled paper, you will be reducing the need to cut down more trees.
Also be sure to use both sides of the paper that you write on before you recycle it. Use cloth products instead of paper products, like napkins, towels, plates, and cups.
These products can be washed and used again, which helps to save trees. Drive less, and carpool when possible. Car exhaust is one of the main contributors to acid rain. Walk or ride your bike to help keep our environment clean. This label indicates that the trees were grown in a well-managed forest. Learn more about forests. By reading, searching the Internet, and visiting temperate deciduous forests, you can learn lots of cool things about this biome.
The temperature varies widely from season to season with cold winters and hot, wet summers. The areas in which deciduous forests are located get about to 1, mm of precipitation spread fairly evenly throughout the year.
During the fall, trees change color and then lose their leaves. This is in preparation for the winter season. Because it gets so cold, the trees have adapted to the winter by going into a period of dormancy or sleep. Figure 1: The distribution of vegetation types as a function of mean annual temperature and precipitation. Figure 4: Biomes of the world Biomes are regions of similar climate and dominant plant types. The climate of deserts is dominated by low precipitation, generally below mm yr -1 Figure 7.
However, there is a lot of variability in desert types, with hot deserts, cold deserts, high elevation deserts, and rain shadow deserts.
Consequently, there is a great deal of variation in the biodiversity, productivity and organisms found in different types of desert.
The dominant plant biomass in most deserts is composed of perennial shrubs with extensive roots and small, gray or white leaves. However, in warm deserts, therophytes annual plants can make up most of the species diversity Figure 2.
Desert annuals can survive unpredictable dry periods as seeds. Seeds may remain viable in the soil for several years, until the appropriate rainfall and temperature conditions occur, after which they will germinate.
These annuals grow rapidly, completing their life cycle in a few weeks, then flowering and setting seed before soil water reserves are depleted. Winter desert annuals in North American deserts can generate over 1 kg m -2 of biomass in a wet year. With the exception of large blooms of annuals, net primary productivity in most deserts is low and extremely variable. There is a positive relationship between productivity and precipitation, and values can range from near 0 to g m -2 yr Just as with savannas, productivity will vary with soil depth and local drainage patterns e.
Figure 5: Tropical forest biome climate diagram Climate in these areas show little seasonal variation with high yearly rainfall and relatively constant, warm temperatures. Grassland biomes occur primarily in the interiors of continents Figure 4 and are characterized by large seasonal temperature variations, with hot summers and cold winters Figure 8.
Precipitation varies, with a strong summer peak. The type of grassland community that develops, and the productivity of grasslands, depends strongly upon precipitation. Higher precipitation leads to tall grass prairie with a high biodiversity of grasses and forbs. Lower precipitation leads to short grass prairies and arid grasslands. Figure 6: Savanna biome climate diagram Savannas are located north and south of tropical forest biomes and are characterized by lower yearly rainfall and longer dry seasons.
Net primary productivity in dry grasslands may be g m -2 yr -1 , while higher precipitation may support up to 1 kg m -2 yr Grasslands grade into deciduous forest biomes on their wetter margins, and deserts on their drier margins. The borders between grasslands and other biomes are dynamic and shift according to precipitation, disturbance, fire and drought. Fire and drought will favor grassland over forest communities. Figure 7: Desert biome climate diagram There is a greater variability in desert types, with hot deserts, cold deserts, high elevation deserts, and rain shadow deserts.
Three major selective forces dominate the evolution of plant traits in grasslands, recurring fire, periodic drought, and grazing. These factors have led to the dominance of hemicryptophytes in grasslands with perennating organs located at or below the soil surface. Many grasses have below ground rhizomes connecting above ground shoots or tillers. Grass blades grow from the bottom up, with actively dividing meristems at the base of the leaf. Thus when grazers eat the grass blade, the meristem continues to divide and the blade can continue to grow.
Grasses are often decay-resistant, and recurring cool, fast moving surface fires started by lightning at the end of summer aid in nutrient recycling. Fires stimulate productivity and the germination of fire resistant seeds. Figure 8: Grassland biome climate diagram Grassland biomes occur primarily in the interiors of continents and are characterized by large seasonal temperature variations, with hot summers and cold winters. Animals such as gray kangaroos Macropus giganteus in Australia, Bison Bison bonasus and horses Equus spp.
Remnant herds in North America suggest that disturbances due to grazers increased local biodiversity by creating openings that rare species could colonize. Large grazers also accelerated plant decomposition through their droppings, creating nutrient hotspots that altered species composition. Temperature deciduous forests occur in mid-latitudes Figure 4 where cool winters, warm summers, and high year round precipitation occurs Figure 9.
Net primary productivity ranges from — g m -2 yr -1 with high litter production. Litter serves as a major pathway for nutrient recycling. This biome is named for the dominant trees that drop their leaves during the winter months. These forests may have an overstory of 20—30 m tall trees, an understory of 5—10 m trees and shrubs, a shrub layer around 1—2 m in height, and a ground layer of herbaceous plants. Biodiversity is relatively high in this biome due to the niche partitioning allowed by the multiple forest layers.
More complex forests are associated with a greater number of animal species; for example, bird species diversity shows a positive correlation with forest height and number of layers. Figure 9: Temperate deciduous forest climate diagram Temperature deciduous forests occur in mid-latitudes and are characterized by cool winters, warm summers, and high year round precipitation occurs.
This small biome about 1. Unrelated evergreen, sclerophyllous shrubs and trees have evolved independently in each of these areas, representing a striking example of convergent evolution.
Net primary productivity varies from — g m -2 yr -1 , dependent upon water availability, soil depth, and age of the stand. These temperatures mean that temperate forests have defined growing seasons during the spring, summer, and early fall. Precipitation is relatively constant throughout the year and ranges between 75 cm and cm Deciduous trees are the dominant plant in this biome with fewer evergreen conifers.
Deciduous trees lose their leaves each fall and remain leafless in the winter. Thus, little photosynthesis occurs during the dormant winter period. Each spring, new leaves appear as temperature increases. Because of the dormant period, the net primary productivity of temperate forests is less than that of tropical rainforests. In addition, temperate forests show far less diversity of tree species than tropical rainforest biomes. The trees of the temperate forests leaf out and shade much of the ground.
However, more sunlight reaches the ground in this biome than in tropical rainforests because trees in temperate forests do not grow as tall as the trees in tropical rainforests. The soils of the temperate forests are rich in inorganic and organic nutrients compared to tropical rainforests.
This is because of the thick layer of leaf litter on forest floors and reduced leaching of nutrients by rainfall. As this leaf litter decays, nutrients are returned to the soil. The leaf litter also protects soil from erosion, insulates the ground, and provides habitats for invertebrates and their predators. Figure 9. Deciduous trees are the dominant plant in the temperate forest. The boreal forest, also known as taiga or coniferous forest , is found roughly between 50 o and 60 o north latitude across most of Canada, Alaska, Russia, and northern Europe Figure 10 below.
Boreal forests are also found above a certain elevation and below high elevations where trees cannot grow in mountain ranges throughout the Northern Hemisphere. This biome has cold, dry winters and short, cool, wet summers. The annual precipitation is from 40 cm to cm The long and cold winters in the boreal forest have led to the predominance of cold-tolerant cone-bearing plants.
These are evergreen coniferous trees like pines, spruce, and fir, which retain their needle-shaped leaves year-round. Evergreen trees can photosynthesize earlier in the spring than deciduous trees because less energy from the Sun is required to warm a needle-like leaf than a broad leaf. Evergreen trees grow faster than deciduous trees in the boreal forest. In addition, soils in boreal forest regions tend to be acidic with little available nitrogen. Leaves are a nitrogen-rich structure and deciduous trees must produce a new set of these nitrogen-rich structures each year.
Therefore, coniferous trees that retain nitrogen-rich needles in a nitrogen limiting environment may have had a competitive advantage over the broad-leafed deciduous trees. The net primary productivity of boreal forests is lower than that of temperate forests and tropical wet forests.
The aboveground biomass of boreal forests is high because these slow-growing tree species are long-lived and accumulate standing biomass over time. Species diversity is less than that seen in temperate forests and tropical rainforests.
Boreal forests lack the layered forest structure seen in tropical rainforests or, to a lesser degree, temperate forests. The structure of a boreal forest is often only a tree layer and a ground layer. When conifer needles are dropped, they decompose more slowly than broad leaves; therefore, fewer nutrients are returned to the soil to fuel plant growth.
Figure The boreal forest taiga has low lying plants and conifer trees.
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