What is a grassland ?
Grassland is an area where the annual rainfall is insufficient to support a luxuriant growth of trees, but is still high enough so that deserts are not formed. Grasslands are however not restricted to low rainfall areas. Several grassland types form either clearings in different forest types or are located on hill slopes with patches of forests along nala courses and depressions as in the shola region of South India. Grassland ecosystems form Himalayan pastures, the terai grassland of the foothills, semi-arid grasslands of Western and Central Inndia, in scrublands of the Deccan Plateau and in the Shola forests of the Western Ghats, Nilgiri and Annamalai ranges. Thus depending on the quantity of rain, there are tall, medium and short grasses. Natural grasslands have a variety of grasses, forbs (small plants) and herbs. These differ according to the different grassland types.
Each grassland type has its specific herbivores and carnivores. The grassland herbivores are mostly fleet footed animals that live in herds. They tend to form herds as a protective mechanism. Animal life in the grassland evolved along two lines: those that run, such as the blackbuck, wolf and the cheetah; and those that burrow such as the hedgehog and the gerbil. Running is useful in pursuit or flight. The fastest wild animals of the world live in open grasslands.
Grasslands also have an enormous number of insects. These insects attract a large number of predatory animals like the lizards and birds.
In the past grass covered areas were considered to be the ‘common property’ of a village community. Over-utilisation and misuse of these ‘common’ grazing lands has led to their degradation. However due to our ever increasing population these grassland are being converted into agricultural lands through the development of dams and canals.
The Asiatic Cheetah that once roamed the Indian subcontinent is now extinct. Asian lions are now restricted to a single Sanctuary in Gujrat. Ecologists estimate that more that 43% of the Indian subcontinent is in the process of changing from grassland to desert.
Himalayan pastures
We have the Himalayan pastures in the Himalayas, which extends upto the snowline. These grasslands at the lower level are found along with coniferous or broad-leaved forests. The Himalayan wildlife require both the forest and the grassland ecosystem. Several wild sheep and goat such as the Goral are found here.
Terai grasslands
The Terai grasslands at the foothills of the Himalayas consist of tall elephant grass along with Sal forest. The largest herbivore of the Terai is the elephant. It requires an enormous amount of tall grass to feed on. The Terai grasslands form the habitat of the Swamp deer, Wild buffalo and the Rhinoceros.
Semi-arid grasslands
The semi-arid grasslands of the Western and Central India are interspersed with thorn forests. Some of the very important Indian animals such as the blackbuck, chinkara and endangered birds like the Great Indian Bustard are found here. The apex predator of this ecosystem was the cheetah which is now extinct in India.
Shola grasslands
The Shola grasslands are found in high rainfall areas in Southern India. They are located on hill slopes with patches of forest that occur along the nala courses. The Nilgiri Thar is found only in these grasslands. It is now highly endangered.
Grasses
Grasses are very often considered as small plants that are insignificant and do not have much value. However in reality they are a very important plant species that have over 10000 different types. They are found everywhere in deserts, in snow covered areas, in mountainous regions, on the coasts and even in water. Most significantly the grains of grasses form the staple food of people all over the world.
Grasses belong to a group of plants that have more than 10,000 species. Like other plats grasses also have stems, roots, leaves, flowers and fruits.
The roots of the grass plants are fibrous and form a strong web under the ground, which makes it difficult to pull the grass out. They thus hold the soil tightly and fo not allow it to get blown away by the wind or washed away by water. Grasses thus play an important role in conservation of soil and moisture.
The stems of the grass plants are called as culms. They are generally cylindrical, hollow and jointed. Sometimes as in sugarcane, these culms may be filled with a soft tissue. The elongated hollow sections are interspersed with compact solid sections called nodes. Unlike other plants, grass stems grow from the nodes, not from the tops or the ends of the branches. This helps grasses to grow rapidly even when they are grazed on by a variety of animals.
Some stems grow vertically. Others may trail along the ground. These are called as stolons.
Grasses also have rhizomes or underground stems which are an intricate part of their structure. Rhizomes are brown in colour and also have nodes and internodes. Rhizomes are important as they help grasses to hold on to the soil. They also play a major role in propagation as they send up a large number of new shoots. They also play a very important role in the survival of grasses when they are burnt, as they remain unharmed when the surface vegetation is burnt and quickly send up replacements.
The leaves of grasses are ribbon like with parallel veins. The leaves encircle the stem above each node in a sheath and then protrude out in different directions.
Grasses are flowering plants. The flowers are extremely small and do not have petals. They normally occur in groups. These flowers are neither brightly coloured nor scented as they are mostly pollinated by wind. They produce a very large number of seeds. The wind carries the seeds to new locations. These seeds often have fine hair like structures. Animals also play an important role in the dispersal of grass seeds. This can happen in many ways: by sticking to an animal’s body as when the seed is pointed and by being eaten and left in animal droppings. Some grasses have seeds that are attached to the plant very lightly. These seeds are designed to be knocked to the ground by rain or passing animals.
Did you konw ?
Can you imaginee a gass that grows upto a height of 30-40 meters? If you sit next to this plant you can even see the stem growing within a couple of hours! This is a species of bamboo called Dendrocalamus giganteus found in Burma that grows at the rate of one metere a day.
Yes, bamboo is a grass too. There are more than 1000 different kinds of bamboos in the world, of which more than 100 are found in India. Unlike other grasses, bamboo flowering occures after 20-60 years while in several others it may not occur until 120 years after the last flowering.
Activity for the Students
How do you recognize a grass? If the stem has a swollen node with each leaf starting its growth at a node, sheathing the stem before splitting to form a blade, then it most certainly belongs to the gras family. Take some time to look closely at grasses and enjoy them.
Whoever among you spot any grass from the chart given below first gets two points.
- Grass that is shorter than your feet.
- Grass that is taller than your hips.
- The shortest grass leaf that you can find.
- Grass leaf with hairy texture.
- Grass with pointed seeds.
After you have spotted it, with the help of your teacher share it with your classmates, lear more about it and sketh it . Remember the key to winning the game is observation!