Field Study to Tai Po Kau Nature Reserve
Date: 13March, 2009
Group Members:
Chan Ka Yan (2)
Kong Mei Yan (8)
Wong Wan Sai (16)
The introduction of the Tai Po Kau Nature Reserve
Tai Po Kau is a forest reserve located on the road between Tai Po and the Chinese
University of Hong Kong. It is Hong Kong's largest secondary forest, and holds good
stands of mature plantation and native trees. It is the best site in Hong Kong for forest
birds. The 1 km forestry road leading to the nature wardens' hut is a good place to look
for flycatchers, minivets, warblers and thrushes. The notice board has a map showing
clearly marked trails of varying distances. The shorter walks are the most frequently
used by local birdwatchers. There is also a birders' logbook in a box on the right side of
the warden's hut.
(A) The weather condition on 12March and 13March
(i) On 12March
the Maximum Air Temperature is 21.6 C
the Minimum Air Temperature is 18.1 C
the Grass Minimum Temperature is 17.8 C
the Relative Humidity is 78-90%
the amount of Rainfall is trace
(ii) On 13March
the Maximum Air Temperature is 24.8 C
the Minimum Air Temperature is 14.4 C
the Grass Minimum Temperature is 13.6 C
the Relative Humidity is 60-96%
the amount of Rainfall is trace
(B) How the amount of vegetation cover affect the stemflow and the quality of the soil
Large amount of vegetation allows more interception and stemflow. Stemflow
means that water flows along the stem. When there is more vegetation, there are
more stems to allow stemflow. Besides, due to the dense vegetation cover, there is
a broad and large root system. When roots capture nutrient, it produces a tight
nutrient cycling. So that the most nutrient is stored at biomass instead of storing in
the soil. This leads to low soil fertility, which is poor soil.
Therefore, the large amount of vegetation leads to an increase in stemflow and the
poor quality of soil.
(C) Observe at least two species and record it on“plant species record form”.
Mosses is a patch many tiny moss plants packed together so that they can hold water
for as long as possible. They do not have roots, and could not get water from them if
they did. Because they cannot find water, they live in two ways. They can live in places
that are always wet; like near a spring, a river, or in a place where there is a lot of fog.
They can also dry up when there is no water. This means that they can never live in dry
places.
A moss does not make seeds. A moss does not have fruit. When the moss has made
food .moss plants swim inside a clump of moss. Two cells combine to make a cell with a
full set of moss DNA. This cell grows into a different kind of moss plant- but it gets all
of its food from a green fuzzy moss plant.
Fern species live in a wide variety of habitats, from remote mountain elevations, to dry
desert rock faces, to bodies of water or in open fields. Ferns only grow within specific
pH ranges; for instance, the climbing fern will only grow in moist, intensely acid soils,
while the bulblet bladder fern is only found on limestone.
(D) How epiphytes adapt to the microclimate of the woodland
Epiphytes grow above the ground surface, using other plants or objects for support.
They reach positions where the light is better or where they can avoid competition for
light.
Since epiphytes have no contact with the soil, the major difficulties they encounter are
shortages of water and nutrients. They have similar adaptations to desert plants, absorb
and store water and restrict its loss. Some stop growing when water is short, but when
it becomes available they are able to absorb it rapidly and resume growth.
Epiphytes obtain nutrients from plant debris which trapped by the branches of the
support tree or amongst the roots.
Some epiphytes have a waxy layer on their surfaces which reduces water loss. The
surface area from which water can be lost is often restricted by having small leaves. In
extreme cases, some epiphytic orchids have leaves that are reduced to tiny scales. The
green aerial roots of these plants carry out photosynthesis.
(E) The differences between the crowns of emergent layer and those of the lower layer
The emergent layers which grow above the general canopy, reaching heights of 45-55
m, few species will grow to 70-80 m tall. They need to be able to withstand the hot
temperatures and strong winds in some areas.
The understory layer lies between the canopy and the forest floor. The understory is
home to a number of birds and snakes, as well as predators. The leaves are much larger
at this level. Many seedlings that will grow to the canopy level are present in the
understory. Only about 5 percent of the sunlight shining on the rainforest reaches the
understory.
(F) The functions performed by buttress roots
They prevent the tree from falling over and help gather more nutrients. They are there
to anchor the tree and soak minerals and nutrients from the ground, a function that
would prove difficult if the tree was unsoundly rooted. The roots helps to support all of
the other trees surrounding it. They can grow up to 15 feet tall and spread for 30 or so
metres above the soil then for another 30 metres below. When the roots spread
horizontally they cover a wider area to collect nutrients. They stay near to the top
because this is where all the main nutrients are. The roots are close to the surface and
can be seen to have spread over a large area.
(G) The advantages that climbers posses in the competition foe nutrients and light
Climbers such as epiphytes, derive only physical support and not nutrition from their
host, though they may sometimes damage the host.
Epiphytic plants use photosynthesis for energy and obtain moisture from the air or
from dampness on the surface of their hosts. Epiphytic plants attached to their hosts
high in the canopy have an advantage over herbs restricted to the ground where there
is less light and herbivores may be more active.
(Example: Judas tree in Western Asia)
(H) Reasons for some trees bear trunk flowers (Cauliflory)
This can allow trees to be pollinated have their seeds dispersed by animals which
cannot climb or fly. With fruit, plants may instead have fruit which drop from the
canopy and ripen only after they reach the ground, an alternative "strategy" to
cauliflory.
(I) The importance of litter to soil quality
After decomposition, litter turns into humus, which will release some organic matter.
There are nutrients inside the organic matter. This will be finally absorbed by plant
roots. These nutrients are essential to maintain a good soil quality. Since the climate of
Hong Kong is cooler than TRF, the humus content is thicker. So that the quality of soil is
fertile.
(J) Observe the soil profile of the entrance
1) The soil profile diagram with labels (Oxisol)
There are large inputs
of rainfall and
sufficient sunlight.
There are large inputs
of organic matter as
there are large
amount of litters.
Leaching will occur
due to the
abundant rainfall.
Base salt (e.g.
calcium,
potassium,
magnesium and
sodium) and silica
will be wear away.
There is rapid break
down of organic
Intense
weathering
A
Leaching
Eluviation
Desilication
matter and tight
recycling of nutrients.
Iron and aluminum
sesquioxide
B
Illuviation
Lateralization
Concretion
(iron release red
color)
Intense
weathering
C
2.) The soil texture by using the feel method.
By using the feel method, the soil texture is sticky. Also, it is wet and contains
more moisture. As Hong Kong is regarded as a sub-tropical area, the temperature is
high and there is abundant rainfall supply. Thus, there is intensive chemical weathering
and more minerals are produced. So the soil in Tai Po Kau nature reserve contains a
high proportion of clay.
3.) The color of the soil
The color of the soil is reddish brown. In Hong Kong, there is high
temperature and sufficient rainfall. Thus, the decomposition rate and chemical
weathering is rapid. There is thick soil. Also, chemical weathering will produce some
base salt. On the other hand, leaching will occur due to the large amount of rainfall. It
will wear away the base salt. (e.g. calcium, magnesium, sodium and potassium).
Moreover, silica will be wear away known as desilication. Some mineral matter that can
not wear away will be illuviated in the B horizon. Iron and aluminium sesquioxide in the
soil will turn the soil to the reddish brown color when it receives sunlight. Laterization
will be finally occurred
4.) A brief account
There is high temperature and the rainfall is abundant. The rainfall is evenly
distributed. As a result, it is favor for the chemical weathering and the bacterial
activities. Rapid chemical weathering will produce more mineral matter and chemical
salt. Also, the decomposition rate is higher and more organic matter is produced.
Leaching will occur because of the large amount of rainfall. Much of the soluble
mineral matter and base salt will be wear away. As a result, the layer of humus is
thinner than the soil layer. Silica is more soluble at a higher temperature and may be
carried away as silicic acid in solution. Iron and aluminium sesquioxide which is
insoluble will turn the soil to reddish brown colour. It will receive sunlight and
laterization will be finally occurred. This is the formation of oxisol.
(K) The flora (plant) of Hong Kong is so diverse in character and numerous in species
In Hong Kong, the species are rich and biodiversity will help to maintain Hong
Kong’s ecosystem. The reason that the plants in Hong Kong are so diverse in character
and numerous in species is the affect of climate.
There is high temperature and the rainfall is abundant. The rainfall is evenly
distributed. It is favour for the plant growing. Also, the recycling of nutrients is very
rapid and plants root will absorb these nutrients very fast. As a result, most of the
nutrients are stored in plants. So there is numerous in species.
In addition, referring to the history of the Tai Po Kau Nature Reserve, there was
further deforestation during the Second World War, but since 1946 the forest has
been protected, with many trees planted. Rather than employ the sparse mix of
non-native species typical of Hong Kong plantations, there was a far-sighted decision
to instead plant and nurture a mixture of tree species, including some that were
uncommon or rare. As a result, plantation is one of the factors that lead to the diversity
of plants.
The reflection after field study
HK doesn’t have abundant rainfall throughout the year (as most precipitated in
summer) but HK still have many species that more than Britain. Because of the relative
humidity and insolation are high during spring and summer. HK have growing season
throughout the year, even it is cold and dry in winter, and you still can see flower or
leaves grow on the trees. With the wet and warm climatic condition, more plant
species can grow in spring and summer months.
Each plant have their own way to survive. There are many competition in the park. It is
difficult for mosses or saprophytes growing, but they can still develop into different
species, how a strong vitality.
Chan Ka Yan
After visiting the Tai Po Kau Nature Reserve, I see that there is a large amount of litter.
Although we locate in a subtropical region (Hong Kong), there is still so much litter.
Also, I observe the stratification of trees too. I found that there are emergency strums,
canopy strums and mosses. Besides, I found that there are a cauliflory flowers and fruits.
And I found the color of soil is reddish, which is oxisol. This visit makes me know more
about tropical vegetation. I can imagine the situation of TRF after this trip. I think this
field trip can help us to understand the lesson more.
Wong Wan Sai
After going to this field trip, I learn more about soil in Hong Kong. As Hong Kong is the
sub-tropical area, there are numerous of species and it is good for our observation.
Also, going to field trip is the application of our knowledge. I can found epiphytes,
buttress roots and many types of plants in there by my eyes and this observation can
help me to more understand the characteristic of these plants. As a result, going to
field trip can help me to strengthen my knowledge.
Kong Mei Yan