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Net primary production and leaf litter consumption by gastropods in mangrove plantations of different ages
Net primary production and leaf litter consumption by gastropods in mangrove plantations of different ages
Year: 2021/MSc. Environmental Science
Name: Tanapon Pongsuvarod
Advisor: Sasitorn Poungparn
Abstract
Mangrove forests play a role in high net primary productivity (NPP). Up to the present, mangrove plantation has been widely conducted. However, the NPP estimation in different ages of the mangrove plantation is still scarce. Moreover, quantitative study of leaf litter consumption by gastropods is limited. This objective of this study is to estimate NPP and leaf litter consumption rate by gastropods in mangrove plantations of different ages, dominated by Avicennia alba. They composed of four stand ages (14, 10, 8, and 6 years in 2018; namely Y1, Y5, Y7 and Y9, respectively) located at Bangpu Nature Education Centre. The results showed that decreased tree-density was high excepted Y1, while total basal area of tree and total biomass increased with increasing the stand age. NPP shows an opposite trend to the stand age. This study found 14 species of gastropods in total. The density of leaf-litter consumed gastropods (family Littorinidae, Iravadiiae, Potamididae) was found the highest in Y1 and correlated with leaf litter consumption rate, but the leaf litter consumption was not different among the stands both in the rainy and dry seasons. In a conclusion, the different vegetation structures among the stand ages caused the differences in NPP, biomass, and gastropod community. The results can be applied for planning mangrove plantation and management on new mudflat to maximize the ecological benefit and sustainable utilization under a limited time frame of mangrove forest restoration.
Seasonal effects on growth and efficiency of nitrogen and phosphorus resorption of Avicennia alba Blume in mangrove forest, estuary of Trat river
Seasonal effects on growth and efficiency of nitrogen and phosphorus resorption of Avicennia alba Blume in mangrove forest, estuary of Trat river
Year: 2020/MSc. BOTANY
Name: Piyapon Kankong
Advisor: Sasitorn Poungparn
Co-advisor: Chadtip Rodtassana
Abstract
Mangrove forests play an important role in carbon storage because they are highly net primary production (NPP) ecosystems. Even most of the trees grow under high saline and anoxic environment due to the effects of tidal inundation. Globally the sea level tends to increase due to global climate change. As a result, salinity regimes and nutrient budgets in mangrove forests have been altered, which may affect the growth of mangrove trees. This study investigated the trunk basal-area increment, leaf emergence, and leaf loss and observed the leaf nutrient resorption of Avicennia alba under the changing of water and soil environments during the rainy and dry seasons, from July 2019 to June 2020. The study site is located in a secondary mangrove forest at the estuary of the Trat River. The results showed a seasonal pattern of the trunk basal- area increment and the leaf emergence that the growth rates were high in the rainy season and consequently decreased in the dry season. During the rainy season, a large amount of rainfall reduced water salinity. The contents of total nitrogen in water tended to increase during the rainy season. Therefore, A. alba absorbed a large amount of freshwater and nitrogen through the root absorption for further tree growth. Moreover, phosphorus resorption efficiency (PRE) increased during the rainy season resulting in high nutrient availability for tree growth. Both the high trunk basal-area increment and leaf emergence rates during the rainy season indicated that A. alba has a growth strategy under salinity and nutrient fluctuations by taking an advantage of the high growth rate under conditions of low water salinity. Moreover, the high efficiency of nutrient resorption during the rainy season also responded to the rapid growth. These findings explain how mangrove ecosystem can maintain their high global carbon stock.
Carbon budget of coarse woody debris in secondary mangrove forest
Carbon budget of coarse woody debris in secondary mangrove forest
Year: 2016/ Ph.D. BOTANY
Name: Suthathip Umnouysin
Advisor: Sasitorn Poungparn
Abstract
Climate change has resulted in decreasing area and efficiency of carbon sequestration in mangrove ecosystem. To understand carbon dynamics in mangrove ecosystem, it is necessary to study net ecosystem production (NEP) which is a key to clarify carbon-sink efficiency. A common method of NEP estimation is summation method by balancing between net primary production (NPP) and heterotrophic respiration (HR). NPP is a summation of biomass increment (∆B) and litter production (L). However, previous NEP estimations by this method in the mangrove forests excluded coarse woody debris (CWD) which has been mentioned as an important carbon pool because of low decomposition rate. Therefore, the aim of this study is to estimate carbon budget of CWD for estimation of NEP in a secondary mangrove forest at the Trat River estuary. The CWD distribution was investigated in 1-ha permanent plot showing clear three vagetation zones of dominant tree species from the river fringe to inland as Avicennia, Rhizophora and Xylocarpus zone, respectively. The results showed that CWD mass was the highest in the Xylocarpus zone (6.33 t ha-1), followed by the Rhizophora zone (6.14 t ha-1), and the Avicennia zone (3.55 t ha-1), respectively. Component of CWD mass in each category differed by vegetation zone. Mass of downed wood CWD was the highest in the Rhizophora zone, while mass of CWD in standing dead trees was the highest in the Xylocarpus zone. Then, annual ∆B, L and CWD input were recorded, and showed that the Avicennia zone had the highest ∆B, while the Rhizophora zone had the highest CWD input. Given by the summation of ∆B, L and CWD, the NPP ranged from 5.97 to 11.9 t C ha-1 y-1. The highest contribution of CWD to NPP was in the Rhizophora zone (37%). Moreover, the rates of CWD respiration which is a component of HR was also measured. They were 0.22, 0.52 and 0.28 t C ha-1 y-1 for the Avicennia, Rhizophora and Xylocarpus zones, respectively. The Soil respiration was calculated by using an equation of Poungparn et al. (2009). It was 2.30, 2.20 and 2.12 t C ha-1 y-1 for the Avicennia, Rhizophora and Xylocarpus zones, respectively. The total HR was calculated as 2.52, 2.72, and 2.40 t C ha-1 y-1 for the Avicennia, Rhizophora and Xylocarpus zones, respectively. Finally, the NEP was balanced as 8.88, 9.18, and 3.57 t C ha-1 y-1 for the Avicennia, Rhizophora and Xylocarpus zones, respectively. The results indicated a significant role of the CWD for the NEP estimation in the mangrove forest. The data obtained by this study is a merit for enhancing the accuracy of NEP estimation in the mangrove forest.
Photosynthesis and some related factors of red mangrove Rhizophora mucronata Poir. At Tungka-Sawi Bay, Chumphon Province
Photosynthesis and some related factors of red mangrove Rhizophora mucronata Poir. At Tungka-Sawi Bay, Chumphon Province
Year: 2011/MSc. BOTANY
Name: Suthathip Umnouysin
Advisor: Sasitorn Poungparn
Abstract
The photosynthesis of R. mucronata study was conducted in four stand ages (1, 3, 5 and 9 years old) during rainy and dry seasons at Tungka-Sawi Bay, Chumphon Province. Light response curves of R. mucronata were established. Maximum photosynthetic rate, stomatal conductance (g[subscript s]), intercellular CO2 concentration (Ci) and transpiration rate (Tr) were measured. Then, water use efficiency was calculated. Furthermore, some factors that related to the photosynthesis, including specific leaf area (SLA), nitrogen content (N), sodium ion (Na+), chloride ion (Cl-) in leaf, leaf anatomy and environmental factors (i.e., physical and chemical properties of water and soil) were examined. The results of light response curve showed that quantum yield and light saturation point of all stands were not different between rainy and dry season. Nevertheless, light compensation point and respiration rate in the dry season were higher than those in the rainy season according to the high air temperature and soil water salinity in the dry season. The maximum photosynthetic rates of all stands were lower in the dry season than those in the rainy season. In dry season, the soil water salinity increases, resulting in reduction of gs, Ci, Tr, leaf N and thickness of mesophyll layer but increasing Cl- concentration in leaves. Correlation analysis indicated that there was a significant correlation between the maximum photosynthetic rates of R. mucronata and related factors in each stand. The factors that had the most correlation with the photosynthesis of most stand were gs, leaf N and soil water salinity.
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