New Guinea is the world’s largest, most speciose, and most culturally rich tropical island, and the little-studied Mamberamo Basin of Papua (Indonesian New Guinea) is recognised among the region’s most-important areas for biological diversity. Here, we examined the floodplain forests in the indigenous territory of Papasena, within the Mamberamo-Foja Wildlife Reserve in the Mamberamo Basin. As part of a training activity with local researchers, students, and civil servants, and with the permission and assistance of the local people, we employed various methods including the field surveys detailed here. We used variable-area tree plots, transects for non-trees and soil sampling, and local informants to document 17 plots: four in old-growth dryland forest, five in old-growth swamp forests (two seasonally flooded and three permanently wet including one dominated by sago, Metroxylon sagu Rottb.), five in secondary forest (fallows), and three in gardens (two in swamps and one on dryland). In total, we measured 475 trees over 10 cm in diameter at 1.3 m (dbh). The swamp forests had high local basal areas (highest value 45.1 m2 ha−1) but relatively low statures (20 m but with emergent trees over 40 m). In total, 422 morphospecies from 247 genera and 89 different families were distinguished. These included 138 tree species and 284 non-tree plant species. A quarter (105) of the morphospecies lacked species-level identifications. The woody families Rubiaceae, Araceae, Moraceae, and Euphorbiaceae were especially diverse, with 20 or more morphospecies each. Tree richness was highest in dryland forest (plot 7 having 28 species in 40 stems over 10 cm dbh) with more variation in the flooded forests. Non-tree vegetation showed similar patterns ranging from 65 species in one 40-by-5 m primary forest plot to just 5 in one seasonally flooded forest plot. The local people identified many plants as useful. Among trees, at least 59 species were useful for construction (the most common use), while, for non-trees, medicinal uses were most frequent. Inceptisols dominated (12 plots), followed by Ultisols and Entisols (3 and 2 plots, respectively). Drainage appeared poor and nutrient availability low, while land-suitability criteria implied little potential for crops aside from sago. We discuss the implication of local practises and more recent developments that may threaten the conservation of these floodplain systems. We underline the key role of local people in the oversight and protection of these ecosystems.
Tag: geomorphology
Mangrove blue carbon dynamics in Papua, Indonesia: effects of hydro-geomorphic setting and land-use change
Mangroves are one of the most efficient organic carbon sink ecosystems which occur along intertidal coastal areas of tropical and subtropical regions. Together with other coastal wetlands such as saltmarsh and seagrass, mangroves have been termed ‘blue carbon’ ecosystems due to their substantial capacity for carbon storage and sequestration. Consequently, policymakers and stakeholders promote mangroves for natural-based climate change mitigation. However, many mangroves across the world are being altered by anthropogenic disturbances including land-use and land-cover change (LULCC). Large-scale LULCC will inevitably affect the magnitude and direction (loss or gain) of the carbon cycle in mangroves.
Assessment of coastal and mangrove vulnerability in the Andaman Island, Indian Ocean
Coastal regions are highly susceptible to the effects of global warming, including rising atmospheric and sea surface temperatures, increased cyclone frequency, and sea level rise. Thus, it is imperative to examine coastal vulnerability to minimize the impact of multiple hazards and protect coastal resources, such as mangroves. Particularly in India studying the vulnerability of coastal zones of Andaman and Nicobar Islands which fall in seismic zone V is critical for conservation efforts. We conducted vulnerability analysis of coastal zones impacted by the 2004 earthquake, causing varying degrees of ground upliftment and subsidence. We compared coastal vulnerability among sites that experienced uplift, no change, and subsidence (the southern portion). Our analysis utilized the Coastal and Mangrove Vulnerability Index (CVI and MVI) to measure and compare vulnerability in six zones distributed along uplift and subsidence gradient. High-resolution satellite imagery including WorldView-2, 3, and GeoEye-1 from year 2022 are utilized on this study. The CVI and MVI offers a good way to measure and compare vulnerabilities across sites and offer insights for better management. The CVI and MVI results indicate that approximately 34% of coastal grids and over 23% of mangrove grids across all zones are highly to extremely highly vulnerable. Subsided zones were found to be more vulnerable than uplifted zones. These findings suggest that large-scale natural disturbances such as tectonic displacement have the potential to impact coastal vegetation and mangrove cover can become even more vulnerable. In conclusion, our study emphasizes the importance of vulnerability analyses in coastal regions, especially in areas prone to seismic activity. Our findings have direct implications for conservation and restoration efforts and underscore the need for continued monitoring and mitigation efforts to safeguard coastal resources for long-term sustainability.
Mangrove vegetation response to alteration in coastal geomorphology after an earthquake in Andaman Islands, India
The 2004 Sumatra-Andaman earthquake caused a devastating tsunami and shifts in land elevations, which had an instantaneous as well as the long-term impact on the ecology of Andaman Islands. Especially, the coastal uplift and subsidence has altered the tidal regime, leading to mass mortality and degradation of mangroves (~150 sq. km). The tectonic shift in the Andaman archipelago has created three broader geographical units: North Andaman with coastal uplift (~1.3 m)– sea level drop (SLD) scenario; Middle Andaman with minor to no change in coastal geomorphology – no change scenario; and South Andaman with coastal subsidence (~1.1 m)– sea level rise (SLR) scenario. How these changes in tidal regime has influenced mangrove vegetation remain less understood. Therefore, we assessed mangrove vegetation characteristics across the Andaman Islands to examine mangrove response to coastal uplift and subsidence after 16 years since the disturbance. The uplifted sites mimicking SLD scenario appeared more destructive to vegetation (tree density – 771/ha) in comparison to subsided sites mimicking SLR scenario (tree density – 937/ha), while no change sites with highest tree density (1288/ha) showed lowest impacts to vegetation. The species diversity (H’=Shannon-Wiener index) within recruitment cohorts (seedlings: <1 cm DBH and saplings: ≥1 cm and <5 cm DBH) sapling (H’=1.57), and seedling (H’=1.48) was significantly higher than the trees (H’=1.2). Rhizophora apiculata and Ceriops tagal were the dominant species (cumulative IVI 60%) found in survived mangrove forests demonstrating their high resilience for sudden changes in tidal regime. Our study provided a comprehensive account of mangrove vegetation response after a major disruptive event in 2004. Long-term monitoring of these novel sites would enhance our understanding of mangrove response to sea level change, which can also provide significant insights for restoration and management of mangroves.