User talk:Dinomics

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Plant Habitat

Adapt to Survive Over thousands of years, plants gradually adapt to their habitat—they begin to grow in ways & forms that make them better able to survive & reproduce in the conditions there. This is called adaptation.

Temperate Forests Around 5000 years ago, almost two-thirds of the world’s land was covered in forests. Since then, people have cut down more than half the forests to make way for farms and cities. The woodlands that remain form very rich & important habitats. Deciduous trees survive the cold winters rather as hibernating animals do—by storing energy in their bodies & resting until spring.

Taiga Taiga is the name given to forests in northerly parts of the world, where it is very cold in winter & summers are short. Taiga forests mostly contain conifers, trees that carry their seeds in cones, such as pine and fir. How do conifers survive in places where few other trees can & where temperatures are freezing for half the year? The main reason for their success is the needle-like shape of their leaves. All leaves contain water and all trees lose some water from their leaves. The water evaporates—turns to water vapour & becomes part of air. In winter, water in the ground is frozen into ice & plants cannot use it, so it is vitally important for a plant to hold on to any water it has. Needle leaves lose less water than other kinds of leaves. Because they are very thin, there is less space from which the water can escape. The needles are also covered with a thin layer of wax that acts like a coat, protecting them from cold & helping to prevent them from drying out.

Tropical Rainforests Tropical rainforests lie close to the Equator, in an area called the tropics. In this habitat there are no seasons; it is warm & sunny & it rains almost every day.

Tundra 1/5 of the Earth’s surface is covered in frozen land called tundra. Instead of growing up, the Artic willow grows across the ground & can be as long as other willow trees are tall.

Deserts The hot deserts of the world are places of extremes—warm as an oven in the daytime & often very cold at night. As rain falls only in short bursts, it is important for plants to collect as much of it as it can. Cacti have roots that grow just below the surface, but they spread far & wide, ready to collect any dew or rainwater that seeps in. Others such as gourd and saguaro, have very long roots that can reach water sources deep underground.

Ponds & Lakes •	Nutrients from dead plants & animal matter & from the mud at the bottom of the pond, are dissolved in the water. •	Water lilies have flat & rounded leaves. They also have a waxy surface that repels rainwater & are shaped so the water runs off them—if too much water gathered on their leafy rafts, they would sink.

Rivers & Streams •	Eel grass has long thin leaves that offer little resistance to water flow. This means that they tend to drift in the direction of the water rather than trying to stand upright & fight against its flow. •	Water milfoil has finely divided feathery leaves for the same reason. The water filters through them as it passes, rather than crashing against them. •	Plants on the edge have an important part to play in the health of the riverbank. Their roots bind the soil at the edge together, preventing the rushing water from washing it away (erosion). This is also important to the animal life in the river, because many creatures, including water voles & otters, make their burrows in the banks along waterways.

Swamps & Marshes •	They are flat areas of waterlogged land, where water reaches or covers the surface of the ground for most of the time. Swamps often form where a lake has filled up with mud& plants, while marshes are common at the mouths of rivers where some water moves. They both contain grasses such as cattails, bulrush & sedges, but swamps have more trees than marshes, such as red maple, cypress& alder. •	In swamps & marshes, dead plants decay so slowly that the soil has a limited supply of nutrients. Carnivorous plants make food by photosynthesis as other plants do, but because the soil is poor they get the other nutrients they need from animals. Marsh pitchers have jug-shaped leaves containing digestive juices. Insects are attracted to the smell inside the pitcher but once they fall in the liquid, they cannot climb out again as the sides are too slippery. Bladderworts live under water & suck in tiny animals through special trap doors.

In the sea (Ocean algae) Very few plants live in deep seas because plants need light for photosynthesis & light cannot reach down into deep water. However, tiny algae—plants without leaves, stems, roots or flowers—float on the waves, even far out to sea. Algae can be found all over the oceans, but large ‘blooms’ of algae are found in colder waters.