The relevance of using in situ carbon and nitrogen data and satellite images to assess aboveground carbon and nitrogen stocks for supporting national REDD + programmes in Africa

Table 3 Mean nitrogen density (Mg ha⁻¹ of N) and total nitrogen stocks (Mg of N) by LULC class at the watershed scale

LULC/LUCa	Descriptive statistic
	Range of nitrogen density (Mg ha⁻¹ N)		Mean nitrogen density (Mg ha⁻¹N) (SE)	Total nitrogen stocks (Mg N) (SE)
	Min	Max	Mean nitrogen density (Mg ha⁻¹N) (SE)	Total nitrogen stocks (Mg N) (SE)
Forest land				740.37 ± 0.021
Riparian forest and woodland	0.170	0.285	0.212 (0.014)	72.41 ± 0.014
Savannah Woodland	0.045	0.160	0.096 (0.005)	530.79 ± 0.005
Shrub Savannah	0.008	0.064	0.032 (0.001)	137.16 ± 0.001
Grassland				0.825 ± 0.0006
Savannah grassland	0.0001	0.0178	0.0085 (0.0068)	0.825 ± 0.0.0006
Cropland				62.57 ± 0.0006
Cropland and Fallow	0.00018	0.0252	0.0077 (0.0067)	62.57 ± 0.0006
Settlements				5.20 ± 0.002
Settlements	0.0017	0.0201	0.0106 (0.0021)	5.20 ± 0.002
Agroforestry				1.53 ± 0.022
Cashew plantation	0.017	0.340	0.0741 (0.022)	1.53 ± 0.022
Plantation				5.01 ± 0323
Eucalyptus grandis	0.012	1.091	0.321 (0.088)	4.42 ± 0.088
Tectona grandis	0.058	0.418	0.291 (0.115)	0.26 ± 0.115
Azadirachta indica	0.114	0.425	0.317 (0.101)	0.23 ± 0.101
Gmelina arborea	0.024	0.079	0.058 (0.017)	0.10 ± 0.017

The age of plantations and agroforestry system varied from 5 to 45 years which explained the large standard error (SE) and the large variance relative to the mean obtained from their plots data. The area of each LULC class was provided in the Table 1