Abiotic Components of an Ecosystem

First, try to explain the following observations:

a. Talahib grows well in abundant sunlight, while ferns grow well in the shade.

b. Pine trees grow well in cold countries and, in the Philippines, at high elevations. On the other hand, banana plants thrive in tropical countries.

c. The gabi plant grows well in water-soaked ground, while the rose plant prefers moderate water only.

d. Bamboo can tolerate strong winds, while the banana plant cannot

Certain aspects of the physical environment determine the distribution of plants and animals on land. Three of these are discussed below:

1) climate                  2) soil and                 3) surface relief, or topography

The contrasting behaviors or characteristics of plants cited at the start of this section illustrate the effect of climatic conditions. Identify which of the following climatic elements explains each of the observations: 1. Light          2. Moisture               3. Temperature and             4. Wind

Second, study the following situations:

a. Crop yield in kaingin becomes less and less after two years of continuous planting of the same crop, usually corn or rice. Nutrient loss in this case is rather fast.

b. After continuous application of fertilizer, the productivity of a farm drops because the soil has become acidic. The farmer either applies lime or burns the agricultural wastes on the farm itself to correct the acidity of the soil.

c. Most crops grow better in loam, which generally has higher moisture content than other types of soil.

The principal soil types are sand, loam and clay. They differ, not only in the kind of substances they contain, but also in the size of the soil particles which determines the amount of water the soil can hold as well as the amount of water with dissolved minerals that leaches out of the soil.

The three situations cited above illustrate the effect of soil on plant growth. Specially the soil features are 1) nutrients in the soil,             2. acidity of the soil             3. Moisture content of the soil

The size of the soil particles is important because it affects both the moisture content and nutrient content of the soil. Soil moisture is lost fastest from sand and slowest from clay, either through evaporation or through leaching. Water that percolates through the soil dissolves some minerals from the soil. Incidentally, more acidic soils lose more minerals through leaching than less acidic soils.

Third, consider the following observations:

a. Certain plants and animals are found only in high elevations. For example, cloud rats (Phloeomys and Crateromys to scientists) live only in high mountains such as those in Central Northern Luzon, Southern Luzon, and Mindanao, whereas Rabor’s Giant Mountain Rat (Rattus rabori) is found only in the highlands of Mt. Malindang in Zamboanga Peninsula.

b. Cogon and Talahib are two plants that grow abundantly in Philippine grasslands. But they do not necessarily have the same distribution. Talahib, which prefers more moisture, is found in lowlands and along gentle slopes. Cogon, which tolerates less moisture, can grow along steeper slopes.

c. In the Philippines, the sun is almost always directly overhead at noon. But in high altitudes, the orientation of mountains may be such that one side receives more sunlight than the other side. As a result, the mountain slope that faces the sun generally has thicker plant growth than the other side.

These observations illustrate the effect of topography – particularly 1) altitude or elevation,       2) angle of slope, and   3) orientation of the slope – on plant and animal life.