Fine root dynamics and associated carbon and nutrient flux in 12 year old acacia mangium at varying stand densities
By: Delphy Rocha.
Contributor(s): Kunhamu, T K (Guide).
Material type:
BookPublisher: Vellanikkara Department of Silviculture and Agroforestry, College of Forestry 2017Description: 163p.Subject(s): Silviculture and AgroforestryDDC classification: 634.9 Online resources: Click here to access online Dissertation note: PhD Abstract: Fine root production has been estimated to account for up to 33% of global annual Net
Primary Production, NPP (Gill and Jackson, 2000). Thus, fine root turnover has important
implications for individual plant growth, plant interactions, and below-ground carbon and
nutrient cycling. Direct and indirect methods for measuring fine root production and
turnover in 12 year old Acacia mangium Willd. at varying stand densities were studied.
Fine root production estimated ranged from 3.8 - 5.75 Mg ha-1 with a turnover of 4 yr-1. It
was estimated that through fine root decomposition about 1.36-2.39 Mg C ha-1, 34.56-
102.52 kg N ha-1, 1.46-3.3 kg P ha-1 and 19.94-33.60 kg K ha-1 is released to soil. Even
though fine root constitutes only 1.7-2.14% of the total tree biomass its contribution to the
system productivity is very high. Attempts were also made to relate fine root production
with various growth variables and in general most of the variables (DBH, basal area per
tree, volume per tree, aboveground biomass per tree and leaf area per tree) gave good
correlation (R>8**) with fine root production when considered on per tree basis. Average
annual litter production was estimated to a range of 9.99-11.69 Mg
ha-1. Interestingly,
annual litter production had a high correlation (R=0.9**) with fine root production.
Through litter decomposition, 1.4-2.07 Mg C ha-1, 36-48 kg N ha-1, 1- 4 kg P ha-1 and 3-6
kg K ha-1 is released to the soil. Total soil carbon stock up to 1m soil depth was estimated
and it was significantly different across different density regimes. Invariably the SOC
concentration was relatively lower in treeless plot compared with A. mangium at different
density regimes. Soil C sequestration was 15.96 - 34.58 Mg C ha-1 and the nutrient content
of soil estimated as 2343.811-948 kg N ha-1, 13.12-21.92 kg P ha-1, 313.52-261.25 kg K
ha-1. Total system C content estimates in the ranges from 148.93 -263.79 Mgha-1. So
Density manipulation plays a significant role on productivity in 12 year old A. mangium.
Hence, management objectives should be based on assessment of their impact on various
productivity attributes
| Item type | Current location | Collection | Call number | Status | Date due | Barcode |
|---|---|---|---|---|---|---|
Theses
|
KAU Central Library, Thrissur Theses | Reference Book | 634.9 DEL/FI (Browse shelf) | Not For Loan | 174054 |
PhD
Fine root production has been estimated to account for up to 33% of global annual Net
Primary Production, NPP (Gill and Jackson, 2000). Thus, fine root turnover has important
implications for individual plant growth, plant interactions, and below-ground carbon and
nutrient cycling. Direct and indirect methods for measuring fine root production and
turnover in 12 year old Acacia mangium Willd. at varying stand densities were studied.
Fine root production estimated ranged from 3.8 - 5.75 Mg ha-1 with a turnover of 4 yr-1. It
was estimated that through fine root decomposition about 1.36-2.39 Mg C ha-1, 34.56-
102.52 kg N ha-1, 1.46-3.3 kg P ha-1 and 19.94-33.60 kg K ha-1 is released to soil. Even
though fine root constitutes only 1.7-2.14% of the total tree biomass its contribution to the
system productivity is very high. Attempts were also made to relate fine root production
with various growth variables and in general most of the variables (DBH, basal area per
tree, volume per tree, aboveground biomass per tree and leaf area per tree) gave good
correlation (R>8**) with fine root production when considered on per tree basis. Average
annual litter production was estimated to a range of 9.99-11.69 Mg
ha-1. Interestingly,
annual litter production had a high correlation (R=0.9**) with fine root production.
Through litter decomposition, 1.4-2.07 Mg C ha-1, 36-48 kg N ha-1, 1- 4 kg P ha-1 and 3-6
kg K ha-1 is released to the soil. Total soil carbon stock up to 1m soil depth was estimated
and it was significantly different across different density regimes. Invariably the SOC
concentration was relatively lower in treeless plot compared with A. mangium at different
density regimes. Soil C sequestration was 15.96 - 34.58 Mg C ha-1 and the nutrient content
of soil estimated as 2343.811-948 kg N ha-1, 13.12-21.92 kg P ha-1, 313.52-261.25 kg K
ha-1. Total system C content estimates in the ranges from 148.93 -263.79 Mgha-1. So
Density manipulation plays a significant role on productivity in 12 year old A. mangium.
Hence, management objectives should be based on assessment of their impact on various
productivity attributes
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