Mangroves 2014, 5 179locating and quantifying mangrove extent

Mangroves are found throughout the tropics, providing critical ecosystem goodsand services to coastal communities and supporting rich biodiversity. Classificationresults allowed partitioning mangroves in to ecologically meaningful, spectrally distinctstrata, wherein field measurements facilitated estimating the first total carbon stocks formangroves in Madagascar. Estimates suggest that higher stature closed-canopy mangroveshave average total vegetation carbon values of 146.8 Mg/ha (±10.2) and soil organicOPEN ACCESSForests 2014, 5 178carbon of 446.2 (±36.9), supporting a growing body of studies that mangroves are amongstthe most carbon-dense tropical forests. Of particular note,Landsat imagery is freely available, offers >40 years of data and has proven critical for bothForests 2014, 5 179locating and quantifying mangrove extent and loss and partitioning mangrove ecosystems to estimateC stocks 40,69–79. Using the localized map to partition the mangroves in to ecologicallymeaningful strata, we also present the first estimates of total C stocks for Malagasy mangroves andcompare them with published values for other terrestrial forest types. Inventory of Existing Mangrove Maps and Assessment of Mangrove DynamicsNational-level datasets providing mangrove coverage over the AOI include maps produced by ordescribed in Mayaux et al. Existingnational-level land-cover and mangrove maps and high spatial resolution imagery viewable throughGoogle Earth were referenced to iteratively aggregate and label clusters according to suspecteddominant mangrove and other land-cover types (Table 1). Mangrove Carbon StocksTo calculate biomass and, subsequently, to estimate C stocks, field surveys were conducted inApril–May and August–September, 2012, using a modified version of the measurement protocoloutlined in Kauffman and Donato 39, employing a stratified sampling design, wherein plots weresystematically located within dominant mangrove cover types.Species Allometric equation Wood density 119 ReferencesAvicennia marina B = 0.1848 × dbh2.3524 0.661 120Bruguiera gymnorrhiza (leaves) B = 0.0679 × dbh1.4914 0.741 121Bruguiera gymnorrhiza (stem) B = 0.464 × (dbh2 × H)0.94275 × p 0.741 22Ceriops tagal (dbh 2–18 cm) B = 10?0.7247 × dbh2.3379 0.803 121Ceriops tagal (dbh 18–25 cm) B = 10?0.494 × dbh2.056 0.803 122Heritiera littoralis (leaves) B = 0.0679 × dbh1.4914 1.074 121Heritiera littoralis (stem) B = 0.464 × (dbh2 × H)0.94275 × p 1.074 22Lumnitzera racemosa B = 0.0214 × (dbh2 × H)1.05655 × p 0.565 22Rhizophora mucronata (leaves) B = 0.0139 × D2.1072 0.867 121Rhizophora mucronata (root) B = 0.0068 × dbh3.1353 0.867 121Rhizophora mucronata (stem) B = 0.0311 × (dbh2 × H)1.00741 × p 0.867 22Sonneratia alba B = 0.0825 × (dbh2 × H)0.89966 × p 0.78 22Xylocarpus granatum B = 0.0830 × (dbh2 × H)0.89806 × p 0.7 223. Overview of Existing Mangrove MapsComparisons confirmed that the USGS-produced maps 86 offered the most representativehistorical and contemporary areal estimates of Ambanja and Ambaro bays’ mangroves. In addition to distinguishing amongst mangrove classes, ourfindings support previous work demonstrating that measurements at SWIR wavelengths can furtherdifferentiate mangroves from terrestrial vegetation 125.1 2 3 4 5 6 7 8 9 10 11 Total User’s (%) Commission (%)Savannah (1) 54 3 0 0 0 0 0 0 0 1 0 58 93 7Woodland (2) 0 39 0 0 0 0 0 0 0 0 0 39 100 0Active crops (3) 0 0 51 0 0 0 0 0 0 0 0 51 100 0Closed-canopy terrestrial forest (4) 0 0 0 54 0 0 0 0 0 0 0 54 100 0Open-canopy terrestrial forest (5) 0 4 0 0 54 0 0 0 0 0 0 58 93 7Closed-canopy mangrove (6) 0 0 0 0 0 79 9 0 0 0 0 88 90 10Open-canopy mangrove I (7) 0 0 0 0 0 11 72 0 2 0 0 85 85 15Open-canopy mangrove II (8) 0 0 0 0 0 0 0 52 0 0 0 52 100 0Deforested mangrove (9) 0 0 0 0 0 0 0 0 60 0 0 60 100 0Exposed soil (10) 0 8 3 0 0 0 0 2 1 53 0 67 79 21Exposed mud (11) 0 0 0 0 0 0 0 0 0 0 54 54 100 0Total 54 54 54 54 54 90 81 54 63 54 54 666Producer’s (%) 100 72 94 100 100 88 89 96 95 98 100 Overall 93.4Omission (%) 0 28 6 0 0 12 11 4 5 2 0 Kappa 0.9Forests 2014, 5 190A comparison with the 24,669 ha of mangrove coverage provided by the 2010 USGS classificationhighlights the shortcomings of localized applications for this national-level dataset (Figure 5). Carbon Plot Locations and Ecological Characteristics of Mapped Mangrove ClassesFigure 6 shows the location of C plots established within mangrove strata. Open-canopymangrove I had average C values of 42.9 Mg/ha (±5.9) (vegetation: n = 28) and 324.4 Mg/ha (±36.5)(SOC: n = 24). The highopen-canopy II SOC values are most likely attributable to the smaller sample size (i.e., n = 4) andadditional plots are required in this mangrove strata to more robustly estimate C.Class Sub-type Spp dominance Height (m) (±1 SD)Trees/ha(±1 SD)d (cm)(±1 SD)Closed-canopy (n = 24)intact, tall, mature stands Avicennia marina 8.6 (n = 1) 1250 (n = 1) 14.9 (n = 1)intact, tall, mature stands Ceriops tagal 7.3 (±1.2) (n = 3) 2625 (±318) (n = 2) 10.1 (±0.5) (n = 3)intact, tall, mature stands Rhizophora mucronata 7 (±1.3) (n = 14) 4719 (±1133) (n = 12) 10.1 (±3) (n = 14)intact, tall, mature stands Sonneratia alba 5.6 (n = 1) 5300 (n = 1) 10.6 (n = 1)very dense medium-tall stands Rhizophora mucronata 4.8 (±0.1) (n = 2) 5600 (±1838) (n = 2) 7.8 (±1.1) (n = 2)intact, tall, mature stands mixed 6.7 (±1.6) (n = 2) 1825 (±248) (n = 2) 11.3 (±2.5) (n = 2)Open-canopy I (n = 28)medium stands Ceriops tagal 4.6 (±0.8) (n = 7) 3300 (±849) (n = 2) 7.5 (±1.6) (n = 7)medium stands Rhizophora mucronata 4.2 (±0.6) (n = 6) 2160 (±498) (n = 5) 7.3 (±1.3) (n = 6)naturally open/very degraded tall variable 5.7 (±0.3) (n = 4) 1525 (±35) (n = 2) 10.1 (±1.2) (n = 4)very dense short stands Ceriops tagal 2.5 (±0.3) (n = 9) 2780 (±750) (n = 5) 5.1 (±0.9) (n = 9)medium stands mixed 4.8 (±0.1) (n = 2) 1800 (±141) (n = 2) 9.5 (±2) (n = 2)Open-canopy II (n = 4) stunted, scrub ecosystems Avicennia marina 1.7 (±0.5) (n = 4) 1306 (±554) (n = 4) 4.6 (±0.2) (n = 4)Forests 2014, 5 194Figure 7.ClassSample depth(cm)Carbon(%)Bulk density(g/cm3)Carbon mass(Mg/ha)Closed-canopy (n = 22) 0–15 4.8 (0.9) 0.77 (0.08) 41.1 (3.5)15–30 4.1 (0.4) 0.73 (0.08) 41.3 (3.7)30–50 4.1 (0.3) 0.73 (0.06) 58.4 (3.9)50–100 4.2 (0.4) 0.72 (0.06) 155.6 (14.9)100–150 3.9 (0.5) 0.70 (0.09) 149.8 (17.4)Total 446.2 (36.9)Open-canopy I (n = 24) 0–15 3.4 (2.9) 0.78 (0.08) 32.5 (3.8)15–30 4.4 (3.6) 0.72 (0.07) 43.1 (5.3)30–50 3.2 (2.6) 0.75 (0.07) 45.2 (5.6)50–100 3.2 (2.6) 0.60 (0.08) 120.7 (16.9)100–150 1.9 (2.2) 0.52 (0.10) 82.9 (18.3)Total 324.3 (36.5)Open-canopy II (n = 4) 0–15 0.6 (0.1) 1.39 (0.04) 12.1 (0.7)15–30 0.6 (0.3) 1.28 (0.05) 10.6 (2.6)30–50 0.8 (0.6) 1.35 (0.06) 22.5 (7.4)50–100 2.2 (1.2) 1.10 (0.03) 120.0 (28.9)100–150 6.1 (2.4) 1.18 (0.08) 351.9 (58.1)Total 517.1 (76.0)A comparison of our results with existing published C stocks for mangroves indicates that ourvalues are comparatively low.Although preliminary, our results support ongoing initiatives investigating the feasibility of andworking towards implementing mangrove carbon financing projects (e.g., Reducing Emissions from050100150200250300350400450500Ecosystem C stocks (mg/ha)Forest typesAbove-ground vegetationcarbonSoil organic carbon 0-30 cmdepth + below-groundvegetation carbonSoil organic carbon 30-100 cmdepthForests 2014, 5 197Deforestation and forest Degradation (REDD)+) and other payments for ecosystem services (PES).

x

Hi!
I'm Johnny!

Would you like to get a custom essay? How about receiving a customized one?

Check it out