Modeling gap dynamics, succession, and disturbance regimes of mangrove forests: MANDY (MANgrove DYnamics)

Despite their important ecosystem benefits for terrestrial and marine flora and fauna and the human livelihood mangrove forests suffer a high loss rate mainly due to human activity. Aside from these impacts, natural forest disturbances exist more commonly in mangroves compared to other forests as a direct consequence of their exposed coastal location. Within this thesis I investigate the influence of natural disturbance regimes on the mangrove forest dynamics focusing in particular on the ecological role of disturbances, disturbance patterns, forest structure, succession behavior and long-term vulnerability evaluation. The study areas were set in the Indian River Lagoon in Florida (USA) and in Can Gio an UNESCO Biosphere Reserve (Vietnam). In addition, theoretical simulation studies were carried out to complement the field studies. Thereby, in our study at the Indian River Lagoon site I investigated the ecosystem response to hurricane events of an artificially impounded mangrove forest. In Can Gio, the suitability of lightning strike – caused gaps for setting a homogenous plantation into more natural-like state according to species composition and forest structure was analyzed. Finally, a theoretical simulation study was carried out to compare lightning strike and hurricane events regarding their homogenization and heterogenization effects on the spatio-temporal forest structure. The findings of the field study in the Indian River Lagoon indicate that hurricane events had a severe impact on forest areas in higher successional stages by creating open patches, whereas areas in lower successional stages remained largely undisturbed. Furthermore, the impoundment determines the species selection of the post-hurricane succession by favoring flooding-tolerant species. However, regeneration was found to be impaired by the artificially high inundation regime at some disturbed patches. The lightning-strike disturbances enhance the species composition in the monospecific plantation in Can Gio by providing a sufficient light regime for entering seeds to establish. In addition, lightning-strike gaps increased the plantation structure complexity. Regenerating lightning-strike gaps remained as “green islands” within windthrow sites in the plantation due to their low stature and provided seeds for surrounding disturbed areas thereby accelerating their recolonization. The results of the simulation analysis of a theoretical landscape showed that in the simulated highly complex natural mature forests all disturbance regimes entail homogenization on the spatial structure compared to an undisturbed scenario. The hurricane scenario showed an increased temporal variation of the forest dynamics whereas lightning-strike gaps were not able to contribute to additional heterogeneity in the simulated area, despite of having the same tree mortality probability during disturbances. The interaction of the large-scale impoundment in the Indian River Lagoon and medium-sized hurricane events is characterized by partially impeded post-hurricane regeneration. In contrast, small-scaled lightning strikes influenced the regeneration of medium-sized windthrow sites positively within the homogenous plantation. We therefore suggest management activities aimed at creating small clearances within the plantation in Can Gio to simulate additional small-scale disturbances in order to facilitate heterogenization of the plantation structure. Natural disturbances are found to be able to enhance the species diversity and the interactions of ecological processes. In particular, where sustainable management strategies focused on maintaining ecosystem services especially in restored sites or plantations act as a supportive part. Natural disturbances are an integral component of mangrove forests and fulfill specific ecological functions. However, our findings indicate that these disturbances, on top of altered environmental conditions associated with climate change and direct human impacts, might jeopardize the natural development in unnatural forest structures as on plantations or restored sites. This thesis gives an extensive overview about the effect of various disturbances in different mangrove forest systems, including semi-natural forests and strongly modified plantations, on species composition and forest structure. Field studies and simulation analyses contribute in equal parts to the results of the thesis

The influence of elicitor Cu2+ and Fe 2+ to asiaticoside level of pennywort (Centella asiatica L. urban) callus

Pennywort (Centella asiatica L. Urban is a medicinal plant used in traditional herbal medicine industry in Indonesia. Production of bioactive compounds through tissue culture can be enhanced by elicitation. This study was an experimental study using completely randomized design.The treatment used is various concentration of metal ions Fe2+ on callus subculture medium namely 0, 90, 100, and 110 mM. with 4 replications to obtain 16 trials. Cu2+ ion concentration treatments used consisted of 4 levels: Cu0 = control (0 mM), Cu1=30 mM , Cu2 = 35 mM, Cu3 =40 mM with 4 replications to obtain 16 trials Elicitor Cu2+ with 40μM concentration resulted in the high levels production of secondary metabolites asiaticoside 4.1595 g / 100g. Elicitor Fe2+ with a concentration of 100 mM asiaticoside produce secondary metabolite 3.836 g / 100g. Elicitor Cu2 + produces higher levels asiaticoside compared with Fe2+

Trend assessment of changing climate patterns over the major agro-climatic zones of Sindh and Punjab

The agriculture sector, due to its significant dependence on climate patterns and water availability, is highly vulnerable to changing climate patterns. Pakistan is an agrarian economy with 30% of its land area under cultivation and 93% of its water resources being utilized for agricultural production. Therefore, the changing climate patterns may adversely affect the agriculture and water resources of the country. This study was conducted to assess the climate variations over the major agro-climatic zones of Sindh and Punjab, which serve as an important hub for the production of major food and cash crops in Pakistan. For this purpose, the climate data of 21 stations were analyzed using the Mann–Kendall test and Sen's slope estimator method for the period 1990–2022. The results obtained from the analysis revealed that, in Sindh, the mean annual temperature rose by ~0.1 to 1.4°C, with ~0.1 to 1.2°C in cotton-wheat Sindh and 0.8 to 1.4°C in rice-other Sindh during the study period. Similarly, in Punjab, the mean annual temperature increased by ~0.1 to 1.0°C, with 0.6 to 0.9°C in cotton-wheat Punjab and 0.2 to 0.6°C in rainfed Punjab. Seasonally, warming was found to be highest during the spring season. The precipitation analysis showed a rising annual precipitation trend in Sindh (+30 to +60 mm) and Punjab (+100 to 300 mm), while the monsoon precipitation increased by ~50 to 200 mm. For winter precipitation, an upward trend was found in mixed Punjab, while the remaining stations showed a declining pattern. Conclusively, the warming temperatures as found in the analysis may result in increased irrigation requirements, soil moisture desiccation, and wilting of crops, ultimately leading to low crop yield and threatening the livelihoods of local farmers. On the other hand, the increasing precipitation may favor national agriculture in terms of less freshwater withdrawals. However, it may also result in increased rainfall-induced floods inundating the crop fields and causing water logging and soil salinization. The study outcomes comprehensively highlighted the prevailing climate trends over the important agro-climatic zones of Pakistan, which may aid in devising an effective climate change adaptation and mitigation strategy to ensure the state of water and food security in the country

The place of artificial reefs in the lives of small-scale fishers in Terengganu, Malaysia

Mainly deployed with the objective of enhancing fisheries resources, artificial reefs began to gain scientific attention in the 1970s. They continue to be a popular agenda in fisheries management, largely due to their potential in improving the lives of coastal communities. Current performance evaluations of artificial reefs, however, continue to focus more on reef effects on the biology and fishing gain of the area where they are deployed. This is despite repeated calls to expand the performance evaluation to include input from artificial reefs users. This thesis examines the dimensions of small-scale fisher- folks' relations with artificial reefs in Terengganu, Malaysia. Using the livelihood approach, the research focuses on non bio-economics data and explores the "currently ignored" domains of artificial reefs to examine the various components of small-scale fishers' livelihood-making. It reveals important insights of the social, cultural, economic, political and ecological changes that have been affected by artificial reef programmes from the perspectives of fishing communities. Based on the results of in-depth interviews carried out in Setiu, Terengganu, it is concluded that although artificial reefs are perceived to enhance local fisheries resources, small-scale fisher-folks' opportunity to benefit from them depends much on how artificial reefs fit into these fishers' fishing strategies, which are strongly related to their livelihood assets, particularly their social and human capitals. Furthermore, artificial reefs' impacts on Setiu small-scale fishers' livelihood are related to their effect on illegal commercial fishery in the area, where although their presence do deter trawl fishery, artificial reefs are paradoxically an ideal fishing site for purse seine fishery. By exploring these various human dimensions of artificial reefs, the thesis offers a broader perspective on the evaluation of this complex marine phenomenon

Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm

Abstract— Online transportation has become a basic requirement of the general public in support of all activities to go to work, school or vacation to the sights. Public transportation services compete to provide the best service so that consumers feel comfortable using the services offered, so that all activities are noticed, one of them is the search for the shortest route in picking the buyer or delivering to the destination. Node Combination method can minimize memory usage and this methode is more optimal when compared to A* and Ant Colony in the shortest route search like Dijkstra algorithm, but can’t store the history node that has been passed. Therefore, using node combination algorithm is very good in searching the shortest distance is not the shortest route. This paper is structured to modify the node combination algorithm to solve the problem of finding the shortest route at the dynamic location obtained from the transport fleet by displaying the nodes that have the shortest distance and will be implemented in the geographic information system in the form of map to facilitate the use of the system. Keywords— Shortest Path, Algorithm Dijkstra, Node Combination, Dynamic Location (key words

Evaluation of parameter regionalization methods for flood simulations in Kelantan river basin

Parameter regionalization techniques are widely used to estimate the parameters for calibrating the hydrological models in ungauged catchments. This study is aimed to compare global average and regression regionalization method for estimating input parameters for Integrated Flood Analysis System (IFAS) model in Kelantan River basin. The calibrated IFAS parameters were obtained from a number of gauged catchments. The model performances obtained using both methods were evaluated using Nash-Sutcliffe coefficient for peak flow, runoff volume and wave shape for flood event during period Dec 2006 – Jan 2007. The regression-based technique performed better than global averaged technique, with the Nash-Sutcliffe model efficiency coefficient values obtained were greater than 0.7 (indicating good model performance) compared to 0.4 for global averaged technique. The results suggest that it is possible to estimate the IFAS parameters using regression-based techniques for flood simulation