Chapter 2 Envi Sci
Chapter 2 Envi Sci
Chapter 2 Envi Sci
OBJECTIVES:
Biomes
A biome is simply a group of land ecosystems with similar climates & organisms.
World’s major types of terrestrial ecosystems: forests, grasslands, and deserts
largely determined by their climates, they cover all of the earth’s land surface except
for ice-covered areas. An area’s biome is determined mostly by its climate,
temperature and precipitation.
The water-covered areas of the earth where life is found, called aquatic life zones,
cover more than 73% of the earth’s surface. Much of the life in these aquatic zones
also varies with their climates.
There are 6 major land biomes and 2 major water ecosystems:
• LAND (6): Rainforests, Deserts, Grasslands, Deciduous Forests, Boreal
Forests, & Tundra
Deserts. An area that receives less than 25 cm of rain per year. Some deserts
receive no precipitation at all during one year. Deserts often undergo large shifts in
temperature during the course of a day.
Savanna. Grassland that is located closer to the equator than prairies Savannas can
receive as much as 120 cm of rain per year. In addition to grass, scattered shrubs
and small trees can grow in the savanna.
Deciduous Forest. Trees that shed their leaves and grow new ones each year (i.e.
oaks and maples). It receive enough rain to support the growth of trees and other
plants (at least 50 cm per year) while growing season is 5 to 6 months long.
Taiga. Mostly contains coniferous trees. These trees produce their seeds in cones
and have leaves shaped like needles (i.e. fir, spruce, hemlock). Taigas experience
very cold winters and warm and rainy summers.
Tundra. Is an extremely cold and dry biome. And usually receives no more
precipitation than a desert biome. Most soil is frozen all year long (permafrost).
While during summer, the top layer of soil thaws, but the rest remains frozen.
Freshwater Ecosystems. Freshwater ecosystems include streams, rivers, ponds &
lakes.
Figure 1
Biodiversity
There are three (3) levels of biodiversity (a) genetic, (b) species and (c) ecosystem.
Genetic Diversity. Genes are responsible for the uniqueness of every living organism
and is crucial for species to survive. For instance, on isolated small islands, the gene
flow is limited within the inhabitants of that particular island hence have less genetic
diversity than those on larger islands.
Species Diversity. Usually measured in terms of total number of species found in a
particular area. For instance, some birds have the ability to fly (Haring Ibon) while
others are ground-dwelling (Palawan Peacock), some plants emit a foul odor
(Rafflesia) while some are sweet smelling
(Waling Waling)
Species- groups of similar individuals that breeds among themselves & produce
fertile offspring.
The Philippines although known to have tropical rain forests has more complex
variety of ecosystems. The Philippine Ecosystems are:
Threats
At the global, regional and local level, threats to biodiversity continues to flourish.
Some of the significant threats to biodiversity are as follows:
1. Illegal killing, capturing and selling of wild species.
2. Projected climate change will also threaten aquatic species, habitats, and
ecosystem services if it causes sea level rise (SLR) as projected during this
century.
3. Deforestation due to mining, illegal logging, forest conversion, kaingin, charcoal
making, irresponsible tourism.
4. Overharvesting of tidal flat and mangrove resources.
5. Illegal and destructive fishing methods.
6. Water shortage due to deforestation.
7. Food shortage due to poor soil quality.
8. Health hazard due to water and air pollution.
SUMMARY
Biomes and biodiversity works hand in hand. Biomes can be more complex
compared to others. It is important to note that each biome has its own ecological
functions. Biodiversity is very much influenced in the gene, species and ecosystems
level. Threats to biodiversity should be addressed by conservation measures.
Table 1
KEY COASTAL HABITATS
Habitat Description
Beaches
ACTIVITY 2-1
SEATWORK 2:
Coral
Coral Reef
Estuaries
Foreshore
Lagoons
Mangroves
Seagrass beds