Showing posts with label Mangrove Ecosystem. Show all posts
Showing posts with label Mangrove Ecosystem. Show all posts

Affect of wind, ocean current, fresh water flow and salinity on Mangrove ecosystem




Wind, ocean current, fresh water flow and salinity have the strong influence on the establishment of mangrove ecosystem and also influence the growth and reproduction of mangroves.

Wind
Wind has influence on waves and currents in coastal areas cause soil erosion and changes in mangrove structure. Plants often depend on winds as agents of pollination and seed dissemination which affects biodiversity.

Ocean current
Ocean currents also vary considerably in rate and direction with climate, weather conditions, seasons, and annual changes.
Ocean current has influence on
¡  The mangrove establishment and its biodiversity.
¡  Mangrove deviations from tropical zone mostly correlate with warm and cold oceanic currents.
¡  The distributional ranges tend to be broader on eastern continental margins than on western coastlines.
¡  The occurrences of mangroves at Japan, 35 to 40o south latitude at the east coast of Africa, Australia and New-Zeeland.

Fresh water flow and Salinity
Salinity and fresh water flow has considerable effect on mangrove establishment, distribution and species composition.

Influences of light, rainfall and temperature on Mangrove Ecosystem




Light, rainfall and temperature have the strong influence on the establishment of mangrove ecosystem and also influence the growth and reproduction of mangroves.

Light 
Mangrove plants are long day plants thus it requires high intensity with long duration of full sunlight. This makes tropical coastal zones an ideal habitat. The optimal range of light intensity for the growth of mangrove species is 3,000- 3,800 Kcal/m2/day.

Rainfall
The amount, duration and distribution of rainfall are important factors that determining the development and distribution of mangrove plants and animals.
ž  Rainfall affects other environmental factors in the mangroves such as
¡  Air and water temperature
¡  Salinity of surface and groundwater
¡  Ultimately affects the survival of mangrove species.
ž   Mangroves thrive in areas with a range of 1500-3000 mm of annual rainfall.

Temperature 
ž  Mangroves are restricted generally to areas where
o   Mean air temperatures of the coldest months are higher than 20°C, and
o   The seasonal range of temperature fluctuation does not exceed 10°C (Walsh, 1974; Chapman, 1975, 1977)
ž  Global distributions of mangroves are limited chiefly by the physiological tolerance of each species to low temperature.
o   For example: Viable propagules  of Rhizophora mangle from Mexico routinely reach at the beaches and estuaries of southern Texas.
o   Some propagules become established, but they usually killed during the freezing winter season (Sherrod, Hockday & McMillan, 1986).

Factors, affecting the distribution of Mangroves

Environmental factors known to influence the distribution of particular mangroves

·        Evaporation rate

·        Frequency of saltwater inundation

·        Hydrology (Tides, currents, sea level and wave action)

·        Geomorphology (Catchment size, Estuary length, Sediment types and Slope)

·        Exposure to freshwater

·        Land runoff

·        Groundwater seepage

·        Land use in the adjacent catchments

 E.g. Cleared catchments tend to have increased sediment runoff

·        Oxygen availability

 E.g. aerobic or anaerobic sediment

·        Nutrient availability and pH

·        Feeding on seeds
             E.g. crabs selectively eat the propagules of certain mangrove species.




Factors affecting the Sundarban




Factors affecting the Sundarbans mangrove forest as the single largest tract of mangrove forest in the world. 
¡  Low salinity
¡  High tidal amplitude
¡  Gentle slope of the forest floor
¡  low elevation of land
¡  Numerous network of rivers
¡  High load of sediments
¡  A high fresh water discharge
¡  Shallow continental shelf
¡  Protected shore
¡  Climate is favorable: tropical and sub-tropical

Can mangroves provide protection from natural calamities?

It is a false imagination that mangrove forest protect coastal area from natural disaster like cyclone, storm, etc. But this idea is completely false rather mangrove grows or built up in a sheltered region. Special characteristics of mangrove species is small root, does not go in deep soil, comparably middle aged and height species from other forest. So Mangrove species are weak to protect itself from Sidor, Ayla etc cyclone. If you observe the wind direction in the ocean heavy wind does not pass over the mangrove forest.

Nutrient in the mangrove ecosystem


Inorganic nutrients
16; Limiting factor: P, N ….
Source:
Rain, river run off, sediment, sea water.

Organic nutrients
Source:
Phytoplankton, diatom, bacteria, algae on tress and roots, dead organic matter, river runoff soil nutrients from coastal and upland erosion, dead plants and animals.

Nutrient fluxes in the mangrove forest
Amount of nutrient which exports from mangrove forest is important parameter of the ecosystem productivity. It is important to identify the various sources of nutrient inputs and outputs from mangrove ecosystem.
Sources:
Static: Fixed nutrient; N P …
Dynamic: Comes from the tidal inundation and upland erosion (Na, K Fe..)

Input of inorganic matter in mangrove ecosystem

1.       Rainfall.
2.       Fresh water runoff from surrounding land forest including both dissolved and particulate boundary nutrient.
3.       N2 fixation.
4.       Mineralization: Heterotrophic conservation of organic nutrient to inorganic nutrient.
5.       Tidal borne dissolved or particulate bound nutrient.
6.       Chemical release from fixed state in soil.
7.       Man made influence (agriculture, drainage, sewage, clearing mangrove areas etc.)
Output of inorganic matter in mangrove ecosystem:
                                    1.       Tidal transport of dissolved and particulate bound nutrient and plant litter.
2.       De-nitrification and volatilization.
3.       Immobilization of organic nitrogen in soil.
4.       Leaching of soils by fresh water.

Ecological Services of Mangroves


River of Sundarban
Sundarban mangrove forest.
      •      Protection against floods, hurricanes and tidal waves.
•      Control of shoreline and riverbank erosion.
•      Biophysical support to other coastal ecosystems.
•      Provision of nursery, breeding and feeding grounds.
•      Maintenance of biodiversity and genetic resources.
•      Storage and recycling of organic matter, nutrients and pollutants.
•      Export of organic matter and nutrients.
•      Biological maintenance of resilience.
•      Production of oxygen.
•      Sink for carbon dioxide.
•      Water catchment and groundwater recharge.
•      Topsoil formation, maintenance of fertility.
•      Influence on local and global climate.

Harvesting operation in Sundarban

Harvesting or logging is a scientific way to conserve our forest as declining resources in the world ecosystem. If we keep our forest to the well being of creature we should logging in well identifying system thus we can reduces the losses while harvesting. Finally our goal is to harvest forest resources to fulfill our necessities without hampering our ecosystem.

Objectives of forest harvesting
·         To prepare the tree for extraction.
·         To extract the prepare tree from forest land to mill site.
·         To minimize the wood damage.
·         To ensure the maximum grade recovery.
·         To ensure maximum efficiency of cutting crew.
·         Maintain a safe environment.

Objective of logging operation
·         To prepare the trees and leaves ready to transportation to a processing and converting facility.
·         To prepare and move logs out of the forest at least coast.
·         To supply proper logging methods so as to cause the least damage to the environment.

Logging operation
Logging plan
We decided to cut one middle aged tree because this was an experimental operation. Here we prefer manual skidding. For making plan we considered vegetation composition, elevation of forest, stand density, under brush, soil condition, risk from wild life etc.
Steps of felling operation
1.      Cleaning around the tree: It is recommended that before start cutting the operation should eliminate all underbrush on a radius of at least 1m from the bole. The larger the bole the radius should be the larger if the tree has large sprouts or sapling. We did it and also cut the tree as close to the ground as possible to avoid stumbling or a quick escape.
2.      Making the undercut: After cleaning around the tree we observed the tree lean and determined the felling direction. There are two common types of undercut. The conventional and Humbolt undercut consist of the oblique cut which is made by both a horizontal and a slope cut in the same side of the tree. We used Humbolt cut.
3.      Back cut: After completing the Humbolt undercut we cut the opposite side of the tree above the 3 cm from the undercut line projection. We cut it except 3.5 cm hinge.
4.      Pulling: After finishing under cut and back cut we pull the tree bole towards our desirable direction and finally we did it.
Log Preparation
We cut the tree bole into two pieces for attaining the desirable size to transportation and further furniture or any other materials manufacturing.
Log Transportation
We used manual log skidding to bring the log into our boat. There is no proper transportation road in there but if we want to do logging operation in a large scale we should make the road by clearing bushy vegetation.

Log transportation facilities in sudarban
Sudarban consists of huge number of big and small rivers. So here water transportation and boat transportation are easy and most used transportation practice.
In Sundarban huge amount of Golpatta produces on the river bank. So people can easily harvest and transport those by boat.
It will be a loss project if we harvest tree species like sundry, geowa, goran, poshur, keora etc by using clear felling system rather selection felling system holds the conservation idea for our future betterment. For these reasons skidding is so tough because animal skidding is not possible for no skidding animal in sundarban and manual skidding is also difficult for unfavorable forest floor.
Mechanical transportation will be preferable but it needs huge logging operation and there is no road transportation facilities rather huge numbers of river channels are in there.
Above all at present logging operation is band in Sundarban. So costly mechanical transportation system will not be applicable rather manual, boat and water transportation is perfect at present.


A boy is harvesting Golpatta.
Golpatta harvesting

Our forest resources decline rapidly day by day. We cannot stop harvesting or logging operation but we should consider our environment our next generation. For these we should do logging operation in scientific way.