Discrimination of mangrove species and mudflat classes using in situ hyperspectral data: a case study of Indian Sundarbans

Figures & data

Figure 1. Location of the study area – Bonnie Camp area at Raidighi Range, Indian Sundarbans, West Bengal.

Table 1. List of mangrove species covered under this study

Scientific name	Abbreviation	Family
Aegiceras corniculatum (L.) Blanco	AC	Myrsinaceae
Aegialitis rotundifolia Roxburgh	AR	Plumbaginaceae
Avicennia alba Blume	AA	Avicenniaceae
Avicennia officinalis L.	AO	Avicenniaceae
Bruguiera cylindrica Blume	BC	Rhizophoraceae
Bruguiera gymnorrhiza (L.) Lamk.	BG	Rhizophoraceae
Ceriops decandra (Griff.) Ding Hou	CD	Rhizophoraceae
Ceriops tagal (Perr.) Robbins	CT	Rhizophoraceae
Excoecaria agallocha L.	EA	Euphorbiaceae
Heritiera fomes Buch. Ham.	HF	Sterculiaceae
Nypa fruticans Wurmb.	NF	Arecaceae
Phoenix paludosa Roxb.	PP	Arecaceae
Rhizophora mucronata Lamk.	RM	Rhizophoraceae
Sonneratia apetala Ham.	SA	Sonneratiaceae
Sonneratia caseolaris Engl.	SC	Sonneratiaceae
Xylocarpus granatum Koen.	XG	Meliaceae
Xylocarpus mekongensis Pierre.	XM	Meliaceae

Figure 2. Profile showing different physiographic zones, mudflat classes (b–e), creek water, tide levels and phyto-association in the Sundarbans Reserve Forest area. The figure also shows field photographs (dated 10.12.09 and 11.12.09) of creek water (a), mud lower (b), mud intermediate (c), mud upper without roots (d) and mud upper with roots (e).

Table 2. Cluster membership of the nine mangrove families

Family/Families	Cluster
Rhizophoraceae	1
Meliaceae	1 or 2
Avicenniaceae, Euphorbiaceae, Sterculiaceae, Arecaceae	2
Myrsinaceae, Plumbaginaceae	3
Sonneratiaceae	2 or 3

Table 3. Distances between the final cluster centres

Cluster	1	2	3
1		1.131	2.183
2	1.131		1.085
3	2.183	1.085

Table 4. Stepwise linear discriminant analysis (SDA), combination of selected wavelengths (λ), Wilks' Lambda (L) and F statistics in the steps of SDA in different cases for canopies

Cases	Step	λ in nm	L	F value
1. AA vs. AO	1	400	0.133	104.55
	2	400, 2310	0.030	240.77
2. SA vs. SC	1	400	0.325	37.46
	2	400, 1540	0.023	363.19
	3	400, 580, 1540	0.016	337.68
	4	400, 580, 1540, 2080	0.010	371.51
	5	400, 550, 580, 1540, 2080	0.006	500.32
	6	400, 550, 580, 1540, 2080, 2150	0.004	555.57
3. XM vs. XG	1	430	0.370	37.49
	2	430, 1000	0.228	35.49
	3	430, 960, 1000	0.027	237.37
	4	430, 690, 960, 1000	0.011	423.03
4. BG vs. BC	1	1730	0.459	28.25
	2	1590, 1730	0.219	41.10
	3	1070, 1590, 1730	0.178	33.87
	4	1070, 1120, 1590, 1730	0.077	62.94
	5	1070, 1120, 1590, 1730, 2340	0.045	85.51
	6	1070, 1120, 1590, 1730, 2240, 2340	0.029	107.68
	7	1070, 1120, 1590, 1730, 2200, 2240, 2340	0.023	110.36
	8	1070, 1120, 1590, 1730, 2070, 2200, 2240, 2340	0.016	134.41
5. CD vs. CT	1	480	0.052	292.57
6. BG vs. BC vs. RM	1	540	0.207	63.31
	2	540, 1680	0.042	61.74
	3	540, 570, 1680	0.010	94.88
	4	540, 570, 1680, 1730	0.006	86.96
7. BG vs. BC vs. CD vs. CT vs. RM	1	1160	0.220	74.63
	2	1160, 1250	0.084	109.04
8. NF vs. PP	1	1000	0.607	12.27
	2	970, 1000	0.029	306.57
	3	720, 970, 1000	0.019	294.65
Notes: The wavelengths in bold represent correlation coefficients ≥0.9 obtained from rotated component matrix of first five principal components. Abbreviations of species as in Table 1.

Table 5. Stepwise linear discriminant analysis (SDA), combination of selected wavelengths (λ), Wilks' Lambda (L) and F statistics in the steps of SDA for different cases of mudflat classes and creek water

Cases	Step	λ in nm	L	F value
1. Mud upper vs. mud intermediate vs. mud lower	1	1290	0.000	33456.44
	2	730, 1290	0.000	24669.65
	3	730, 1190, 1290	0.000	50128.97
	4	730, 1190, 1290, 2010	0.000	1277951.33
2. Mud lower vs. water	1	770	0.000	288186.56
	2	540, 770	0.000	384702.98
	3	540, 550, 770	0.000	401877.34
	4	540, 550, 770, 880	0.000	496638.00
	5	540, 550, 880	0.000	607494.60
	6	540, 550, 740, 880	0.000	783117.40
	7	540, 550, 740, 880, 2150	0.000	1797857.91
3. Mud upper vs. mud with roots	1	770	0.005	1752.96
	2	770, 780	0.001	6554.99
Note: The wavelengths in bold represent correlation coefficients ≥0.9 obtained from rotated component matrix of first three principal components.

Figure 3. Methodology depicted in a flowchart. Abbreviations as in the text.

Figure 4. Canopy reflectance spectra of the nine mangrove families.

Figure 5. Reflectance spectra of the mudflat classes and creek water.

Figure 6. Pair-wise (species of the same genus) elucidation of reflectance spectra of canopies (a, b, c and d). Canopy reflectance profiles of the members of Rhizophoraceae (e).

Figure 7. Scree plot of eigenvalues plotted against component numbers – for canopies (a) and mudflat classes and creek water (c). Rotation component matrix of component 1, 2, 3, 4 [canopies (b)] and 1, 2, 3 [mudflat classes and water (d)]. Filled triangles/squares/circles depict wavelengths exhibiting correlation coefficients ≥0.9.

Figure 8. Field photographs showing the canopy status of the mangrove species of Rhizophoraceae family covered under the study.

Table 6. Summary table for the major outcomes of the present work

Data set	Proportion of uncorrelated bands in the visible region out of the selected ones (%)	Proportion of uncorrelated NIR bands out of the selected ones (%)	Proportion of uncorrelated MIR bands out of the selected ones (%)	Most frequently selected wave-length(s)	Least significant discriminable case	Most significant discriminable case	Maximum number of wavelengths selected for discrimination	Number of uncorrelated wavelengths out of the selected ones
Canopies	–	50	50	400, 1000, 1730	BG vs. BC vs. CD vs. CT vs. RM	SA vs. SC	8 (BG vs. BC)	6
All combinations/ pairs of mudflat classes and creek water	18.18	63.63	18.18	–	All cases notably significant	All cases notably significant	5 (mud lower vs. water)	5
Note: Abbreviations of species as in Table 1.

Naskar , K. R. and Bakshi , D. N. Guha . 1987 . Mangrove Swamps of the Sundarbans: An Ecological Perspective , 264 Kolkata : Naya Prokash .

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