Vien Ngoc Nam

Bio: Vien Ngoc Nam is an academic researcher from Ho Chi Minh City University of Agriculture and Forestry. The author has contributed to research in topics: Mangrove & Extinction. The author has an hindex of 4, co-authored 5 publications receiving 1037 citations.

The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern

Abstract: Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species' probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not enforced.

Carbon stocks in artificially and naturally regenerated mangrove ecosystems in the Mekong Delta

Abstract: Mangrove forests cover a small fraction of the earth’s surface, but contribute disproportionately to ecosystem services, including carbon (C) storage. These forests are being rapidly degraded as demand for economic development grows. In recognition of the multiple benefits of mangrove forests, rehabilitation of degraded forests is being carried out in many regions. This study assesses the potential for restored mangrove forests in Vietnam to sequester and store C, by characterizing two different mangrove restoration areas in the Mekong Delta region. The Can Gio Mangrove Biospheres Reserve (CGMBR) in Ho Chi Minh City was highly degraded during the Vietnam War and was subsequently replanted between 1978 and 1998. The Kien Vang Protection Forest (KVPF) in Ca Mau Province was similarly degraded during the war, but unlike CGMBR, it has experienced natural regeneration over the last 35 years. We find that vegetation structure between two sites are not different significantly, though CGMBR has richer mangrove species diversity than KVPF. The mean of total ecosystem C stocks in planted mangroves of CGMBR (889 ± 111 MgC ha−1) is not significantly different compare to natural regeneration forests of KVPF (844 ± 58 MgC ha−1). Our findings suggest that after 35 years, both anthropogenically and naturally regenerated mangroves appear to store similar levels of C.

Sedimentation and belowground carbon accumulation rates in mangrove forests that differ in diversity and land use: a tale of two mangroves

Abstract: Increased sea level is the climate change effect expected to have the greatest impact on mangrove forest survival. Mangroves have survived extreme fluctuations in sea level in the past through sedimentation and belowground carbon (C) accumulation, yet it is unclear what factors may influence these two parameters. We measured sedimentation, vertical accretion, and belowground C accumulation rates in mangrove forests from the Republic of Palau and Vietnam to examine how diversity (high-Vietnam vs. low-Palau), land use, and location (fringe vs. interior) might influence these parameters. Land use in this study was identified as disturbance and restoration for all mangrove forests sampled in Palau and Vietnam, respectively. Vertical accretion rates were significantly greater in Vietnam (2.44 ± 1.38 cm/year) than Palau mangrove forests (0.47 ± 0.08 cm/year; p < 0.001, F1,17 = 24.96). Vertical accretion rates were positively correlated to diversity (R = 0.43, p < 0.05). However, stronger correlations of accretion to bulk density (R = 0.64, p < 0.01) and significantly higher bulk densities in Vietnamese (0.67 ± 0.04 g/cm3) than Palau mangroves (0.30 ± 0.03 g/cm3; p < 0.001, F1,17 = 54.4) suggests that suspended sediments played a greater role in mangrove forest floor maintenance relative to sea level rise. Average vertical accretion rates were similar between naturally colonized (1.01 ± 0.10 cm/year) and outplanted sites (1.06 ± 0.05 cm/year) and between fringe (1.06 ± 0.12 cm/year) and interior mangrove (0.99 ± 0.09 cm/year) in Vietnam. In Palau, vertical accretion rates did not differ between disturbed (0.42 ± 0.11 cm/year) and undisturbed (0.51 ± 0.13 cm/year) mangrove forests and were higher in fringe (0.61 ± 0.15 cm/year) than interior sites (0.33 ± 0.09 cm/year; p = 0.1, F1,7 = 3.45). Belowground C accumulation rates did not differ between any factors examined. C accumulation rates (69–602 gC/m2/year) were similar to those reported elsewhere in the literature and suggest that intact coastal ecosystems play an important role in the global C cycle, sequestering C at rates that are 10–20× greater than upland forests. Assuming vertical accretion rates measured using 210Pb are an effective proxy for surface elevation, the Vietnamese and Palauan mangroves appear to be keeping up with current rates of sea level rise.

The loss of species: mangrove extinction risk and failure of critical exosystem services

Abstract: Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species’ probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not enforced. Citation: Polidoro BA, Carpenter KE, Collins L, Duke NC, Ellison AM, et al. (2010) The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern. PLoS ONE 5(4): e10095. doi:10.1371/journal.pone.0010095 Editor: Dennis Marinus Hansen, Stanford University, United States of America Received October 7, 2009; Accepted March 16, 2010; Published April 8, 2010 Copyright: 2010 Polidoro et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was generously supported by core funding from Tom Haas and the New Hampshire Charitable Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: bpolidor@odu.edu

Mangroves among the most carbon-rich forests in the tropics

Abstract: Mangrove forests occur along ocean coastlines throughout the tropics, and support numerous ecosystem services, including fisheries production and nutrient cycling. However, the areal extent of mangrove forests has declined by 30-50% over the past half century as a result of coastal development, aquaculture expansion and over-harvesting1, 2, 3, 4. Carbon emissions resulting from mangrove loss are uncertain, owing in part to a lack of broad-scale data on the amount of carbon stored in these ecosystems, particularly below ground5. Here, we quantified whole-ecosystem carbon storage by measuring tree and dead wood biomass, soil carbon content, and soil depth in 25 mangrove forests across a broad area of the Indo-Pacific region—spanning 30° of latitude and 73° of longitude—where mangrove area and diversity are greatest4, 6. These data indicate that mangroves are among the most carbon-rich forests in the tropics, containing on average 1,023 Mg carbon per hectare.

Natural climate solutions

Abstract: Better stewardship of land is needed to achieve the Paris Climate Agreement goal of holding warming to below 2 °C; however, confusion persists about the specific set of land stewardship options available and their mitigation potential. To address this, we identify and quantify "natural climate solutions" (NCS): 20 conservation, restoration, and improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We find that the maximum potential of NCS-when constrained by food security, fiber security, and biodiversity conservation-is 23.8 petagrams of CO2 equivalent (PgCO2e) y-1 (95% CI 20.3-37.4). This is ≥30% higher than prior estimates, which did not include the full range of options and safeguards considered here. About half of this maximum (11.3 PgCO2e y-1) represents cost-effective climate mitigation, assuming the social cost of CO2 pollution is ≥100 USD MgCO2e-1 by 2030. Natural climate solutions can provide 37% of cost-effective CO2 mitigation needed through 2030 for a >66% chance of holding warming to below 2 °C. One-third of this cost-effective NCS mitigation can be delivered at or below 10 USD MgCO2-1 Most NCS actions-if effectively implemented-also offer water filtration, flood buffering, soil health, biodiversity habitat, and enhanced climate resilience. Work remains to better constrain uncertainty of NCS mitigation estimates. Nevertheless, existing knowledge reported here provides a robust basis for immediate global action to improve ecosystem stewardship as a major solution to climate change.

The Impact of Conservation on the Status of the World’s Vertebrates

Abstract: Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species.

Carbon Cycling and Storage in Mangrove Forests

Abstract: Mangroves are ecologically and economically important forests of the tropics. They are highly productive ecosystems with rates of primary production equal to those of tropical humid evergreen forests and coral reefs. Although mangroves occupy only 0.5% of the global coastal area, they contribute 10–15% (24 Tg C y−1) to coastal sediment carbon storage and export 10–11% of the particulate terrestrial carbon to the ocean. Their disproportionate contribution to carbon sequestration is now perceived as a means for conservation and restoration and a way to help ameliorate greenhouse gas emissions. Of immediate concern are potential carbon losses to deforestation (90–970 Tg C y−1) that are greater than these ecosystems' rates of carbon storage. Large reservoirs of dissolved inorganic carbon in deep soils, pumped via subsurface pathways to adjacent waterways, are a large loss of carbon, at a potential rate up to 40% of annual primary production. Patterns of carbon allocation and rates of carbon flux in mangrove f...

Rates and drivers of mangrove deforestation in Southeast Asia, 2000–2012

Abstract: The mangrove forests of Southeast Asia are highly biodiverse and provide multiple ecosystem services upon which millions of people depend. Mangroves enhance fisheries and coastal protection, and store among the highest densities of carbon of any ecosystem globally. Mangrove forests have experienced extensive deforestation owing to global demand for commodities, and previous studies have identified the expansion of aquaculture as largely responsible. The proportional conversion of mangroves to different land use types has not been systematically quantified across Southeast Asia, however, particularly in recent years. In this study we apply a combined geographic information system and remote sensing method to quantify the key proximate drivers (i.e., replacement land uses) of mangrove deforestation in Southeast Asia between 2000 and 2012. Mangrove forests were lost at an average rate of 0.18% per year, which is lower than previously published estimates. In total, more than 100,000 ha of mangroves were removed during the study period, with aquaculture accounting for 30% of this total forest change. The rapid expansion of rice agriculture in Myanmar, and the sustained conversion of mangroves to oil palm plantations in Malaysia and Indonesia, are identified as additional increasing and under-recognized threats to mangrove ecosystems. Our study highlights frontiers of mangrove deforestation in the border states of Myanmar, on Borneo, and in Indonesian Papua. To implement policies that conserve mangrove forests across Southeast Asia, it is essential to consider the national and subnational variation in the land uses that follow deforestation.