Silvicultural objective at watershed management.

1. Silviculture practice for Watershed Management
Manoj Paudel
Msc. Forestry
Faculty of forestry
AFU
Course Code: SWM 601
Course Title: Advance silviculture
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Outline of Presentation
1 INTRODUCTION
2 OBJECTIVES
3 METHODOLOGY
4 FINDINGS AND DISCUSSION
5 CONCLUSION

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INTRODUCTION
 Silviculture comes from the Latin word silvi- ("forest")
and culture ("growing").
 Silviculture is the art and science of managing forests for desired
outcomes, such as wildlife habitat, aesthetics, and timber production.
 The study of forests and woods is termed silvology.
 Silviculture also focuses on making sure that the treatment(s) of forest
stand are used to conserve and improve their productivity.
 Watershed management is a term used to describe the process of
implementing land use practices and water management practices to
protect and improve the quality of the water and other natural resources
within a watershed by managing the use of those land and water
resources in a comprehensive manner (Bharati et al., 2002).
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• Watershed management planning is a process that results in a plan or a
blueprint of how to best protect and improve the water quality and other
natural resources in a watershed.
• This is comprehensive planning process that involves all affected area located
in the watershed is essential to successful watershed management.
Watersheds could be classified into a number of groups.
The usually accepted five levels of watershed delineation based on
geographical area of the watershed are the following;
Macro watershed (> 50,000 Hect)
Sub-watershed (10,000 to 50,000 Hect)
Milli-watershed (1000 to 10000 Hect)
Micro watershed (100 to 1000 Hect)
Mini watershed (1-100 Hect)

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Data collection done from secondary information sources such as:
Surfing related website.
Previous assessment reports.
Published and unpublished research paper.
Informal discussions etc.
Methodology
Objective of this paper is to find silviculture objectives for watershed management
Objective

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• Afforestation and reforestation program was started in 1970's to restore the denuded
hills in Nepal.
• Formal watershed management in Nepal began with the establishment of
the Department of Soil Conservation and Watershed Management in 1974.
• Three years of work (1975 to 1977) in the Phewa Tal catchments in west-central Nepal
by the Department of Soil and Water Conservation, Agriculture, Forest and Water
Supply was the first of integrated management of a water catchment (Fleming, 1983).
• The second half of the 1990s saw the adoption of a participatory and integrated
approach to watershed management (Sharma, 1999).
• Tenth Five-Year Plan (2002–2007) says, “Priority will be given to integrated watershed
management to conserve the underground water and soil in the Chure-Bhawar and
Terai” (NPC, 2003).
• The plan significantly recommends the integrated watershed management approach,
although it only names the Chure hills and the Terai areas.
• The Churia Forest Project is undertaking a conservation-oriented project in the Eastern
Siwaliks (Chaudhary, 2018).
Approach of Watershed Management in Nepal

7. According to Smith (2020), There are three main components in watershed
management .
 land management
 water management
 and biomass management.
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Finding and Discussions
Land Management:
 Land characteristics
like terrain, slope,
formation, depth,
texture, moisture,
infiltration rate.
 soil capability are the
major determinants of
land management
activities in a
watershed.
Water Management
 inflows (precipitation,
surface water inflow, ground
water inflow)
 water use (evaporation,
evapotranspiration,
irrigation, drinking water)
 outflows (surface water
outflow, ground water out
flow)
 storage (surface storage,
ground water storage, root
zone storage)
Biomass Management
 Solid waste
management
 Pollution etc.
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Objectives of Silviculture for Watershed Management
Vegetation play vital role in the protection of top soil.
• The highest soil loss occurs in 1999 and 2007 when a wide area of the Batta
watershed in Tunisa remained bare. However, the soil loss was diminished in 2005
with the presence of vegetation (Kefi & Yoshino, 2011).
• Xinxiao, Xuexia, Jianlao, Manliang, & Yuanyuan (2006) found in small watershed of
losses in Taiwan that with the decrease of plants, the amount of sediment produced
by erosion becomes larger.
• The trees and ground vegetation in forest ecosystems slow water movement and
help stabilize soil.
• The planting of trees in parking lots, especially in bio-retention areas where
stormwater flows work to reduce flooding and stream impairment (Canopy
Interception, 2002).
• SALT technology and other agroforestry techniques are only fulfilled with proper
silviculture techniques.
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1. To prevent top soil loss / Erosion / Mass wasting

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Water pollution is generally classified into one of two very broad areas:
1. Point source: Pollution that can be traced to a relatively specific point of origin
2. Non point source: Issues that arise from wide areas, generally from runoff.
• Vegetation helps to slow water movement, reducing soil erosion, which leads to
less pollutants getting into our waterways.
• Plants, especially woody plants, are very good at removing nutrients (nitrates and
phosphates) and contaminates (such as metals, pesticides, solvents, oils and
hydrocarbons) from soil and water (Smith,2020).
• Example: Single sugar maple growing roadside removed 60mg of cadmium, 140
mg of chromium, 820mg of nickel, and 5200mg of lead in a single growing season
(Coder, 1996).
• Studies in Maryland showed reductions of up to 88% of nitrate and 76% of
phosphorus after agricultural runoff passed through a forest buffer (Canopy
Interception, 2002).
2. To Control Water pollution

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• This study provides new adjusted crop parameter values for monoculture
plantations, particularly those that control surface runoff and baseflow processes
(Tarigan, Wiegand, & Slamet, 2018).
• In a North Carolina Watershed study (Kays, 1980) the mean soil infiltration rate
went from 12.4 in/hr to 4.4 in/hr when a site was converted from forest (duff
layer on soils) to suburban turf.
• Other studies (Bharati et al., 2002) have found similar results when comparing
hourly infiltration rates and soil bulk density of forested areas with crops and
grazed pasture.
• Groundwater budgets calibrated with measurements of drainage and
transpiration in a cultivated woodland in West Africa, demonstrate that
groundwater recharge was maximised at intermediate tree densities (Ilstedt et
al., 2016).
3. To Increase ground water storage

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• Low vegetation results extensive soil disturbance and compaction, however, there
is evidence that large as well as small stormflow peaks may be increased (Boyd et
al., 2008).
• Deforestation activities increase stormflow peaks of a size sufficient to cause
downstream channel and bank erosion.
• Streamflow declines are greater in areas that are restocked with conifers than in
those restocked with hardwood (Boyd et al., 2008).
• It is well known that timber harvest, by reducing evapotranspiration, increases
annual streamflow (Hibbert 1967).
• Results from the Alsea Experimental Watershed (Harr and others 1975) and Coyote
Creek (Harr and others 1979) suggest that 12 to 15 percent surface area
compaction is sufficient to significantly increase large stormflow peaks.
• A nine-year flood could be increased in magnitude by 40 percent and a 30-inch
diameter culvert would become necessary where formerly an 18- inch diameter
culvert would have sufficed(Ilstedt et al., 2016).
4. To maintain Streamflow

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• In ideal sustainable ecosystems, everything is already provided within the
ecosystem for life to survive (Bhatta, 2020) .
• At least 30% of the forest cover was required in an watershed area for sustainable
ecosystem services (Tarigan et al., 2018).
• Forests provide fish and wildlife habitat and help maintain aquatic diversity.
• The guiding principle of forest resources states “If forest is managed sustainably it
will meet social , economical, ecological, cultural, and spiritual needs of present
and future generation”
4. To maintain sustainability of ecosystem

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CONCLUSION
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• Annual soil loss, floods, Erosion, water source pollution could minimized with
proper silviculture techniques.
• Forest play vital role to maintain sustainable streamflow and sustainablity of
ecosystem
• Too many stand in forest area is also not suitable for optimum amount of
ground water recharge. Intermediate number of trees are preferable.
• Research activities related to connection between proper silviculture
practices and watershed management are not sufficent in Nepal .

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