Measuring the role of forest income in mitigating poverty and inequality: evidence from south-eastern Nigeria

Figures & data

Table 1 Quantity of harvested forest products by the sampled households.

Product	Category^a	Volume (kg)	Season
Major NTFPs	Irvingia gabonensis (Bush Mango)	61,829	All year round
	Gnetum africanum (‘Afang’)	51,181	All year round
	Bush Meat	70,725	All year round
	Rattan Cane	43,675	All year round
	Garcinia spp. (Chewing Sticks)	52,276	Dry/rainy season
	Carpolobia sp. (Cattle Sticks)	3915	Dry/rainy season
	Garcinia kola and Cola acuminata (Bitter Kola and native Kola)	23,726	Rainy season
Minor NTFPs	Baillonella toxisperma, Mimusop spp.	7689	All year round
	Brachystegia spp., Lasianthera africana, Heinsia crinita and Piper guineense leaves (Achi, Editan, Atama and Hot leaf)	76,296	Seasonally
	Dacryodes edulis, Palm kernel, Chrysophyllum albidum, Mangifera indica and Aframomum melegueta fruits (Native pears or ibe, Udara, Native mango, Alligator pepper)	71,208	Seasonally
	Mushroom	3892	All year round
	Momordica augustisepala (Sponge)	7653	All year round
	Palm Oil	45,545	All year round
	Sleeping and Roofing mats	10,875	All year round
Fuelwood	Fuelwood	137	All year round
Timber	Timber Products	8241	All year round
^a The names in parentheses are their respective local names as widely known in south-eastern Nigeria.

Table 2 Descriptive statistics for the sampled households (N = 1457).

Variable	Description of variable	Cor. with forest dep.^a	Mean	SD
Age	Age of respondent (years, most recent birthday).	−	40.38	15.25
Community_forest	Households that utilized community forestry for forest extraction (1 if utilized, 0 otherwise)	−	0.94^b	0.23
Educ_1	Head has no formal education	+	0.309^b	0.462
Educ_2	Head has elementary education	+	0.007^b	0.088
Educ_3	Head has primary education	+	0.028^b	0.164
Educ_4	Head has secondary education	−	0.433^b	0.496
Educ_5	Head has tertiary education	−	0.151^b	0.358
Family_land	Households that utilized family-owned land for forest extraction (1 if utilized, 0 otherwise)	+	0.36^b	0.48
Forest_distance	Distance from home to the forest area (in km)	−	3.46	1.64
Wage_income	Per capita wage income (NGN)	±	7006.6	16,561.4
Forest_income	Per capita forest income (NGN)	±	4062.2	12,674.7
Farm_income	Per capita farm income (NGN)	±	2021.5	4,876.2
Commerce	Per capita commercial income (NGN)		1722.6	13,302.5
Transfers_income	Per capita transfer income (NGN)	±	1399.6	10,743.0
Total_income	Total per capita household income (NGN)		16,212.1	27,188.6
Gender	1 if male and 0 otherwise	±	0.86^b	0.35
Household_size	Household number of persons	±	5.14	2.35
Membership	Whether a household belongs to a forest management committee or not (1 if member, 0 otherwise)	±	0.83^b	0.37
Poverty_Status	Proportion of sampled population below the national poverty line	+	0.73^b	0.44
^a Correlation with forest dependence: theoretical construct between forest dependence and household covariates. However, because of mixed findings found in many previous studies, some of the expected signs are indeterminate.
^b Proportion for dummy variables.

Table 3 Income share by source classified by income category.

	Income groups
Income source	Poor	Middle	Rich
Wage_Income	0.15	0.41	0.61
Forest_Income	0.53	0.36	0.21
Farm_Income	0.18	0.06	0.06
Commerce	0.03	0.12	0.08
Transfers_Income	0.11	0.05	0.04

Table 4 FGT decomposition by LGAs, sex and education.

	Without forest income				With forest income
Group variable	P0	P1	P2	Pop share	P0	P1	P2	Pop share
LGAs
Akamkpa LGA	0.80	0.62	0.54	0.10	0.76	0.48	0.35	0.10
Biase LGA	0.85	0.71	0.64	0.08	0.78	0.59	0.48	0.08
BokiLGA	0.75	0.61	0.56	0.06	0.70	0.48	0.38	0.06
Etung LGA	0.73	0.68	0.54	0.09	0.58	0.29	0.19	0.09
Ikom LGA	0.76	0.58	0.47	0.27	0.62	0.34	0.22	0.27
Obubra LGA	0.75	0.74	0.68	0.06	0.72	0.42	0.30	0.06
Obanliku LGA	0.78	0.69	0.57	0.14	0.76	0.56	0.45	0.14
Obudu LGA	0.75	0.62	0.42	0.06	0.72	0.45	0.33	0.06
Yakurr LGA	0.73	0.55	0.35	0.14	0.55	0.29	0.18	0.14
All LGAs	0.77	0.64	0.53		0.69	0.43	0.32
Sex
Male	0.88	0.74	0.66	0.86	0.77	0.51	0.40	0.86
Female	0.79	0.51	0.39	0.14	0.62	0.44	0.26	0.14
Education
No formal education	0.90	0.71	0.62	0.31	0.79	0.51	0.38	0.31
Elementary	0.86	0.73	0.63	0.01	0.74	0.48	0.36	0.01
Primary	0.82	0.78	0.58	0.02	0.72	0.44	0.33	0.02
Secondary	0.68	0.55	0.43	0.43	0.63	0.38	0.31	0.43
Tertiary	0.61	0.43	0.37	0.16	0.56	0.34	0.24	0.16

Table 5 Effects of a 10% increase in forest income on poverty.

Income source	FGT ()	FGT ()	FGT ()
Without forest income	0.765 (0.014)	0.635 (0.012)	0.528 (0.011)
10% increase in forest income	0.661 (0.013)	0.394 (0.011)	0.283 (0.011)
Difference	0.104	0.241	0.245
Percentage change (relative)	13.6%	37.9%	45.5%
Obs. 1457
Note: Standard errors in parentheses.

Table 6 Gini decomposition by income source.

Income Source (1)	(2)	(3)	(4)	(5)	(6)	(7) = 6-2
Wage_Income	0.432	0.857	0.802	0.297	0.574	0.142
Transfers_Others	0.125	0.841	0.457	0.048	0.093	− 0.032
Forest_Income	0.251	0.718	0.444	0.080	0.155	− 0.096
Farm_Income	0.106	0.821	0.450	0.039	0.076	− 0.030
Commerce	0.086	0.934	0.666	0.053	0.103	0.017
Total_Income	1.000	0.518	1.000	0.518
Note: stands for the share of each income source in total income; represents the Gini coefficient of each of the income component; measures the Gini correlation with total income; is the Gini coefficient of total income and calculated using Equation (2); measures the share in Gini of total income and calculate as , where and measures the marginal effect on Gini of total income and reflects the impact of a percentage change in respective income source on overall inequality measure.

Table 7 Gini coefficient with and without forest income.

Index	Coeff.	Std. err.	Conf. int.
Gini with forest income	0.572	0.020	0.532	0.611
Gini without forest income	0.736	0.013	0.711	0.760
Difference	0.164
Percentage Change (Relative)	16.4%
Obs. 1457

Figure 1 Lorenz curves with and without forest income for the region. It shows the degree and extent of inequality in any given society or region. The diagonal line denotes perfect equality and deviations from the line (the curves) measure the extent of inequality. The further away the curve is, the greater the inequality.

Table 8 Comparison of means and SD in household groups.

	Forest income		No forest ncome		μ1 − μ0 ^a
Variable	Mean (μ1)	SD	Mean (μ0)	SD	t-Stat
Forest_Distance	3.45	1.65	3.48	1.57	− 0.03**
Household_Size	5.48	2.76	5.04	2.54	0.43**
Poverty_Status^b	0.38	0.48	0.26	0.44	0.12***
Commerce_Income	1190.66	7380.65	2107.01	18,071.73	− 916.35
Farm_Income	1869.20	15,045.77	1214.37	2343.92	654.83
Forest_Income	17,832.32	48,942.79	0.00	0.00	17,832.32***
Transfers_Income	1911.63	4498.69	2402.48	5996.43	− 490.85***
Wage_Income	5782.82	15,689.39	11,248.57	18,696.56	− 5465.74***
Total_Income	28,586.63		16,972.43		11,614.18***
Obs.	1132		325
Indicated levels of significance **p < 0.01 and ***p < 0.001.
^a Difference in means and their respective levels of significance.
^b If a household income is below the national poverty line and 0 otherwise.

Table 9 Parameter estimates of Tobit model with sample selection^a.

Variable	Probit coeff.	Tobit coeff. (cor. regression)
Age	− 0.003 (0.008)	− 0.086* (0.039)
Community_Forest	0.035 (0.028)	− 0.446 (0.767)
Distance_Forest	− 0.136*** (0.019)	0.266** (0.112)
Educ_1 (Head has no formal educ.)	0.082 (0.053)	0.693 (0.535)
Educ_2 (Head has elementary educ.)	0.063 (0.036)	− 0.089 (0.157)
Educ_3(Head has primary education)	− 0.061 (0.039)	1.587 (0.870)
Educ_4 (Head has secondary educ.)	− 0.646** (0.303)	− 0.352 (0.433)
Educ_5 (Head has tertiary education)	− 0.490 (0.394)	− 0.861* (0.474)
Family_Land	0.048 (0.132)	0.378*** (0.133)
Commerce_Income	0.000001 (0.00004)	− 0.287 (0.169)
Farm_Income	− 0.00003 (0.00007)	− 0.130 (0.093)
Wage_Income	0.00002 (0.00001)	− 1.180*** (0.098)
Transfer_Income	− 0.00002* (0.00001)	− 1.052*** (0.273)
Gender	− 0.144 (0.336)	− 0.225*** (0.070)
Household_Size	0.074** (0.035)	0.585 (0.474)
Membership	0.609** (0.296)	1.251 (0.832)
Own_Communal	0.108 (0.597)	0.416 (0.599)
Poverty_Status^b	1.048 (0.616)	6.145*** (3.734)
Constant	− 0.477 (1.02)	− 1.675 (1.782)
Rho		0.564** (0.263)
Obs.	1457	1132
Left-censored obs.		325
Log likelihood function		− 13,939.31
χ^2		271.92
Pseudo R ^2		0.14
Note: Figures in parentheses are standard errors and *p < 0.05, **p < 0.01 and ***p < 0.001.
^a The dependent variable in the Tobit model is forest income, while for the Probit, it is 1 if a household participates in forest extraction and 0 otherwise (i.e. does not participate).
^b 1 If a household income is below the national poverty line, and 0 otherwise.