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The Riau Islands are a group of small islands whose entire land is divided into watersheds. One of the watersheds in the Riau Islands that is currently the main source of raw water for the community is Sei Pulai. The condition of the watershed on Bintan Island is greatly influenced by its morphometrics. The purpose of this study is to determine the morphological characteristics of the Pulai watershed on Bintan Island. This research was conducted in 2024 with observation by survey. Data processing is carried out by physical mapping of watersheds (soil, slope and geology). The results of the analysis showed that the Island watershed was included in the category of high rainfall (average rainfall of 2,500 -< 3,000 mm/year) but the intensity of rainfall was relatively low with an average ± 19.11 mm/day; the widest geological characteristics were composed of Pre-Tertiary and Quaternary sedimentary formations and igneous rocks consisting of granite and diorite; geomorphological characteristics consist of hills and undulating, rivers have low relief, laminar river flows and no rapids are found, with clear river water color; The slope of the Pulai watershed varies with class I slopes covering an area of ±412 Ha (7%); class II covering an area of ±4,071 Ha (74%); class III covering an area of ±897 Ha (16%); class IV covering an area of ±36 Ha (1%) and class V covering an area of ±83 Ha (2%); the shape of the slope of the Pulai watershed which has a hilly area with a sunken slope will produce a sharper hydrograph uplift. In general, the morphological characteristics of the Pulai watershed are geologically dominated by slopes of 8-15%, while geomorphology is dominated by the shape of old volcanic plains. Efforts are needed to rehabilitate and plant protected areas to overcome erosion caused by the slope of hilly land and fragile soil characteristics, especially protected areas outside forest areas during the rainy season.

This study aims to determine the correlation between local knowledge and values and the effectiveness of community-based waste management.. This study uses quantitative and qualitative approaches. The sampling points were divided into four clusters representing the four sides of the island by interviewing 97 respondents. Quantitative data were analyzed using correlation analysis, while qualitative data were analyzed descriptively. The results showed that local knowledge and values significantly affected the effectiveness of waste management, which was visualized with heatmaps. The strength of the color shows visualization; the redder, the more substantial and more positive the value, and the color’s intensity reflects the correlation’s magnitude. The strongest correlation analysis of knowledge factors on effectiveness is shown by the continuity variable with a value of 0.50, and the weakest correlation is community involvement with a value of -0.17. Then, the strongest correlation between local values and management effectiveness is shown by the sustainability value variable and general knowledge value with a value of 0.76, while the cultural practice value and the importance of values with a value of 0.55 show the weakest correlation. The research findings conclude that community-based waste management intervention strategies, especially in small island areas, can make good practices of traditional knowledge sustainability values and local values of local communities the main consideration so that waste management can be more effective.

The mangrove ecosystem acts as a carbon absorber in the atmosphere with more absorption capacity than other types of forest ecosystems. The mangrove sylvo-ecotourism area in Tanjungpiayu Village, Batam City, is part of the forest and land rehabilitation program carried out by BPDAS Sei Jang Duriangkang in the Riau Islands region. In an effort to provide data and information regarding the potential for carbon absorption in mangrove forest ecosystems resulting from the rehabilitation program, it is necessary to calculate the stored carbon stock as a reference for monitoring in subsequent years. The research was carried out from August to September 2023. The method used was the roaming method without harvesting using an allometric model. Data analysis was carried out by calculating the value of biomass, carbon stock and CO2 absorption. The analysis results show that the average total mangrove biomass at the top surface (ABG) and below the surface (BGB) is 420.50 tons/Ha with a biomass composition of AGB of 265.23 tons/Ha, and BGB of 155.27 tons/Ha. Ha. The average value of total carbon stock is 197.63 tonC/Ha with a carbon stock composition of AGB of 124.66 tonC/Ha and BGB of 72.97 tonC/Ha. Furthermore, the average value of total carbon uptake is 724.65 CO2 e ton /Ha with a carbon uptake composition of ABG of 457.07 CO2 e ton /Ha and BGB of 267.58 CO2 e ton /Ha.

Global warming is characterized by high concentrations of greenhouse gas emissions, namely CO2, in the atmosphere. Mangrove ecosystems play a role in mitigating global climate change because they can absorb carbon through photosynthesis and then store it in a carbon pool, which includes Above Ground Biomass (AGB), Below Ground Biomass (BGB), litter or dead wood, and sediment. This study aimed to determine the value of biomass, carbon stocks, and CO2 sequestration in the mangrove ecosystem in the Riau Island. Carbon stocks were estimated by collecting data on AGB, BGB, and dead wood using the non-destructive allometric modeling method, and sediment sampling was carried out at 30 cm intervals until the discovery of humus soil. There are eight research stations spread across Riau Island. The results of the biomass calculation are then converted into carbon stock values and CO2 sequestration. The result showed that the mangrove ecosystem in Riau Island had a biomass value of 1854,54 tons/ha, estimated carbon stocks of 2052,78 tonsC/ha, and a CO2 sequestration of 7527,52 tonsC/ha. The mangrove ecosystem in Riau Island has an area of 79.228,91 Ha so it can store carbon reserves of 162.639.342 tonsC. The amount of CO2 can be minimized or controlled by reducing emissions and conserving forests, namely by improving mangrove management according to the function of mangrove forests.

There are several former bauxite mining areas on Bintan Island which until now have been left open and not managed properly. In Tanjungpinang, the location of the former bauxite mine is located around the mangrove forest ecosystem. The impact of bauxite mining that changes the structure, texture, and physical of the soil can interfere with the development of the root system and the growth of surrounding plants, including mangroves. Therefore, it is necessary to know the health condition of mangroves around the former bauxite mining area. The method used is a cluster plot by calculating the percentage of tree damage based on organ location, type, and level of damage. The results of the analysis show that the health condition of the mangrove forest in Tanjungpinang City is healthy (50,9%); slightly damaged (40,4%) and moderately damaged (8,8%). The locations of the organs that suffered the most damage were roots, lower and upper stems, and leaves. The most common type of damage found roots submerged in red mud; stems and leaves covered with dust and red sand; termite; broken stem; roots break and die; broken shoots; and the leaves change color. The greatest severity is found between 10% and 20%.