ECOSYSTEMS
WEATHER, CLIMATE, VEGETATION AND SOILS
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OBJECTIVES

Define an ecosystem, population, community, producers, consumers,
decomposers.
 Describe how nutrients are recycled in an ecosystem.
 Explain the importance of the climate and soils in the development of
ecosystems.
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Definitions
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A population – all individuals of the same species
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A community – the populations living together
An ecosystem is a community of plants and animals living within a particular
physical environment, which is linked by a flow of materials through the nonliving as well as the living sections of the system (= the community + non-living
part of the environment).
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Living components: plants, animals, humans, bacteria.
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Non-living components: atmosphere, water, soil minerals, climate.
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Freshwater pond ecosystem
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Ecosystem = community + non-living part of the environment
An ecosystem has many components: inputs, producers, primary consumers, secondary consumers and
decomposers.
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Inputs – add nutrients, water or energy to the system. For example: rainfall, nutrients, sunshine.
Producers – are green plants. They grow through photosynthesis. They make direct use of rainwater,
sunshine, and minerals.
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Primary consumers – are animals which feed directly off the plants such as parrots, bees and monkeys.
They are known as herbivores.
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Secondary consumers – feed off the primary consumers and off each other. They include lizards, jaguars,
spiders and birds.
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Decomposers – feed off dead organic matter. They include fungi, termites, earthworms and bacteria.
When organic matter has been broken down into humus by the decomposers, it is stored in the soil until
the nutrients it contains are used again by the producers.
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Nutrient cycling in an ecosystem
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ADAPTATIONS OF VEGETATION TO THE
ENVIRONMENTAL FACTORS OF CLIMATE, SOIL
AND BIOTIC CONDITIONS
IMPORTANCE OF CLIMATE, SOILS AND BIOTIC CONDITIONS
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IMPORTANCE OF CLIMATE
• Both rainfall and temperature affect how the vegetation adapts
to form a particular type of ecosystem.
• Plant growth is encouraged where there is a warm climate and
high rainfall all year round. If the climate is too cold or too hot,
there is less plant growth. There is a continuous growth of plants
in the Caribbean because of no low temperatures. High
temperatures along with moisture speed up decomposition. As a
result, fallen leaves rapidly decompose in tropical environment.
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IMPORTANCE OF SOILS
• Soils provide the material in which plants can anchor their roots.
Soil is formed from mineral matter (from the weathering of
bedrock) and organic material (from rotting vegetation which
forms humus). Some soils hold water and nutrients well allowing
them to be taken up by plant roots and result in a wider
community of plants and wildlife.
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IMPORTANCE OF BIOTIC CONDITIONS
• Living organisms play an important role in the development of
ecosystems by co-existing together in the same environment and
by recycling nutrients. Human activity, such as agriculture, fires,
logging, pollution or the introduction of new species can harm
fragile ecosystems.
• For this reason, ecosystems need to be managed carefully to
preserve them for future generations.
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BIOMES
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Ecosystems can be small scale, such as a freshwater pond or coral reef, or they can
be large scale as a tropical rainforest or desert.
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Large scale ecosystems are called biomes.
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TROPICAL RAINFOREST
BIOME
OBJECTIVES
At the end of the lesson, students will be able to:
• Describe the characteristics of the climate, vegetation and
soil in an equatorial region.
• Locate areas in the Caribbean (and around the world) where
tropical rainforests are located.
• Draw the structure of a tropical rainforest.
• Discuss the relationship between the climate, vegetation and
soil of an equatorial region.
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WORLD MAP OF VEGETATION TYPES
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LOCATION
• Within the Tropics
• Between 10⁰ N and 10 ⁰ S of the Equator e.g. includes
Guyana and Suriname basins in the Caribbean,
Amazon and Congo basins.\
• N.B.
Tropical rainforest is the most productive natural
ecosystem in the world. 40% of world’s species of
plants and animals live in the rainforest.
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CLIMATE
• Temperatures are high and constant all year ~ 27º C
• Little seasonal variation: equal hours of sunlight and darkness
hence no annual seasons
• Air is usually humid so it may feel hot.
• High rainfall all through the year; 1000 – 2000 mm per year
• Two peak rainfall seasons – one when the zone of unstable
weather around the ITCZ is moving north in June and moving
back south in December.91
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CLIMATE GRAPH
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VEGETATION –
• Tropical rainforests
• High productivity and very diverse i.e. Many species of plants
and animals are present.
• One of the main features of the tropical rainforest is the
layering (stratification) of plants and trees.
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Structure of tropical rainforest
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Top canopy – has the very tallest trees called emergents, of heights exceeding 40
metres. They compete with each other to reach maximum sunlight. Many birds and
insects live in this habitat.
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Middle canopy – tops of trees in this layer form a dense green canopy. It contains
90% of wildlife including most birds, mammals (sloths and monkeys). Plants called
epiphytes live on branches high in the canopy to absorb nutrients directly from
water and air. Lianas (woody creepers) are rooted to the ground but carried by trees
into the canopy where they have leaves and flowers.
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Lower canopy – above 5 – 10m from the forest floor and comprises mostly small
trees and saplings. With limited sunlight, the vegetation is more open.
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Shrub and ground layer – very shaded conditions. Shade-loving plants like small
rubber and Swiss cheese plants are found here. Wildlife here eats fruit and seed from
the litter.
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ADAPTATIONS OF THE TROPICAL RAINFOREST VEGETATION TO
EQUATORIAL CLIMATE
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Evergreen trees - the warm and wet climate all year round means that there is no seasonal
leaf fall, so trees grow and shed their leaves all throughout the year.
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Smooth thin bark on their trunks – lack of frost and fire means they do not need thick
protective barks
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Buttress roots – taller trees (emergents) have wide buttress roots to provide extra stability
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Dark green leathery leaves – to resist intense sunshine
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Drip-tip leaves – to allow them to shed water quickly after a tropical downpour.
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To promote productivity, flowers and fruit grow directly from the trunks and branches of
the trees – cauliflory. The seeds of the emergent trees are light and fluffy, enabling them
to be readily dispersed by the wind that blows above the main canopy.
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SOILS
To describe the main constituents of soil and the factors affecting the
development of latosols
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Constituents of soil
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Soil can be defined as ‘ a mixture of minerals, organic matter, gases, liquids and organisms
that together support life on Earth.
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The five main constituents of soils are:
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Inorganic (mineral) matter –derived from weathered rock, or sediment (the parent
material). It provide an anchor for plant roots and weathered minerals release important
nutrients or plant foods.
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Organic matter – rotted (decomposed) vegetation which provides important nutrients for
plant growth and helps to retain moisture in the soil.
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Gases and liquids – soil contains air pockets of air or water; maintains healthy growing
conditions.
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Organisms – biota such as earthworms mix up the soil by dragging down surface litter into
the topsoil.
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SOIL LAYERS
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SOILS – LATOSOLS
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Latosols are deep soils that typically form in tropical rainforest environments
where relatively heavy rainfall facilitates leaching.
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Heavy tropical downpours quickly dissolve and wash away nutrients through the
soil. This is called leaching.
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They are characterized by being red in colour due to high concentrations of iron
and aluminium.
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They are generally NOT fertile.
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Factors in the development of latosols
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Climate- there is constant wetting and drying of the soil layer causes chemical
weathering of the parent material. The high rainfall leads water to drain
through the soil, dissolve minerals like iron and aluminium and redepositing
them further down (leaching). Warm climate promotes the rapid
decomposition of leaf litter as fungi and bacteria thrive in these conditions.
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Vegetation – lush vegetation provides plenty dead organic matter to be
decomposed. Plants quickly absorb the nutrients and leave soil infertile.
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Biota – many organisms thrive in soil’s warm and wet conditions
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Water – plenty leaching as water carries away nutrients to lower soil horizons.
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ACTIVITY
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Complete the blank spaces on the climate, vegetation and soils in an equatorial
region.
Equatorial regions are located between ___________degrees and ____________
degrees of the Equator. One country in the Caribbean that has an equatorial
climate is ____________________. The daily temperatures in an equatorial region
are ___________________ and rainfall amounts are ________________ per year.
________________________________ are the main type vegetation in an
equatorial region and two characteristics of this vegetation are
________________________________________ and
____________________________________. The soils in an equatorial region are
called _____________________. They are prone to ____________________ where
some minerals are washed out of the soil quickly after heavy rain.
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