The study was conducted in two agroclimatic areas following a north-south rainfall gradient in the Maradi region, located in the south-central part of Niger Republic, at approximately 13.5˚ of North latitude and 7.1˚ of East longitude ([13]), namely the northern and the southern Sahelian areas, as illustrated in , which shows the location of the selected villages within the study area. The southern Sahelian area is characterized by a semi-arid climate, with annual rainfall ranging from 500 to 700 mm ([16]). In the southern Sahelian area, vegetation is denser with a tree and shrub layer and predominantly sandy-loamy soils with good water retention capacity ([37]). The northern Sahelian area is the driest part of the Maradi region, marking a transition to the Sahara. The climate is semi-arid to arid type, with an annual rainfall ranging from 300 to 400 mm ([33]). The northern Sahelian area vegetation is made mainly of shrub and tree steppes, with relatively sparse vegetation cover. Soils are mainly sandy to loamy, with low water retention capacity ([37]). The selected villages are presented according to their agroclimatic location, as shown in .

Figure 1. Selected villages’ location in the study area.

Table 1.Villages of the study area.

These villages were chosen based on their climatic differences, their proximity to the defined land use units, and their accessibility.

A pre-survey was done by contacting local stakeholders in order to get household data by terroir. A sample was then determined using the following formula ([4]):

where: n = sample size; t = confidence level; N = parent population; the estimated proportion of farmers using NTFPs as resources; with a margin of error of 5%.

The sample is then of 379 households heads old of at least 18 years. A two-stage stratified sampling was used to ensure adequate household representation. Villages were stratified by ecological proximity (land-use types and agroecological conditions) and sociolinguistic criteria to capture key differences in resource availability and harvesting practices. This approach allows the study to account for relevant population heterogeneity and enables meaningful comparisons between similar villages.Data collected from households heads included socio-economic characteristics, the fields size, and others information on NTFPs, such as the number of species collected, quantities harvested, collection location and distance, perceptions of climate change, pest attacks and excessive logging practices, as well as the degradation or disappearance level of NTFPs, measured by the binary variable “disappeared.” All information was collected via a questionnaire integrated into the KoBoCollect application (version 1.29.3) and checked to eliminate inconsistencies and missing values before statistical analysis.

Household survey data collected with KoboCollect were processed and analyzed in Stata 16.0 software. Descriptive statistics were first computed, including species citation frequencies to identify the most important woody resources across the study area. To assess the determinants of NTFP availability, a linear regression model was estimated, linking household socio-economic characteristics, farm characteristics, and NTFP-related practices to the total annual quantity of NTFPs harvested per household.

Each variable included in the model was selected based on its theoretical potential to influence NTFP availability and harvesting. Household socio-economic characteristics reflect harvesting capacity, farm characteristics capture access to resources, and NTFP-related practices (number of species collected, collection distance, pest attacks, excessive logging, and climate perceptions) measure harvesting intensity and environmental and contextual factors.

The variable “perception of climate change” was included because farmers’ perceptions influence adaptive behaviors, such as selective harvesting or tree conservation, even in the absence of objective meteorological data ([5].[5]).

The dependent variable being continuous, the ordinary least squares (OLS) method was chosen, as it provides unbiased and efficient estimators under classical assumptions ([12]). Statistical assumptions were tested: residual normality was assessed, and due to observed deviations, the dependent variable was log-transformed; homoscedasticity was examined using the Breusch-Pagan test and corrected via robust standard errors with the White test; model specification was validated (_hatsq p-value > 0.005); finally, no multicollinearity issues were detected (VIF < 10).

Such models are commonly used to explain household-level variation in NTFP collection ([2]; [14]). The model was specified as follows:

where Qthousehold / year represents the total quantity of NTFPs collected per household per year and ϵ the error term.

In the degradation analysis, a binary logit model was applied to estimate the probability of a species being reported as extinct (1 = extinct, 0 = available), using the same explanatory variables. Marginal effects were calculated to ease interpretation. Similar Logit applications have been used to assess forest resource degradation and household harvesting pressures in West African and Sahelian contexts ([24]; [29]; [36]). These approaches provide robust insights into both the availability and the risk of disappearance of NTFPs in the study area. The Logit equation model was as follows:

Indeed, although the pseudo R² of the logit model is relatively low (0.0592), which is common in the analysis of complex phenomena, the prediction test shows that the model correctly classified 69.68% of the observations. This confirms that the model retains an acceptable explanatory power and provides relevant insights into NTFP degradation.

As shown in , the conceptual diagram illustrates the relationships between household characteristics (sex, education level, household size, field size), the availability and degradation of non-timber forest products (NTFPs), and the main influencing factors (quantity of NTFPs collected per household per year, species disappearance, number of species exploited, collection distance, agro-climatic area, climate change, pest attacks, overlogging, and food insecurity.

Figure 2. Conceptual diagram.

3.1.1. Socio-Demographic and Economic Characteristics of Households

lists the socio-economic characteristics of the households surveyed in the northern and southern Sahelian areas of the Maradi region. The majority of household heads are male gender (67.39%). The average age of household heads is approximately 41.8 years, and the mean household size is 9.91 persons, indicating large households with a substantial family labor force.

Table 2. Socio-demographic and economic characteristics of households.

Regarding education level, most of the household heads have received formal schooling (84.01%). The dominant ethnic group is Hausa (90.95%), followed by Fulani, Tuareg, and Kanuri. The cultivated area size per household ranges from 2.05 ha in the southern Sahel to 3.35 ha in the north, with an average size of 2.81 ha.

3.1.2. Species Providing NTFPs and Their Importance

A total of 42 woody species were identified, as presented in , where ten species are highlighted for their relatively high citation frequency. For transparency and comparability with other studies, the full list of all species and their importance according to agro-climatic areas is available in (Appendix 1).

In the North Sahelian area, Maerua crassifolia (15.05%), Lannea microcarpa (11.72%), and Piliostigma reticulatum (8.37%) emerged as the most prominent species, followed by Guiera senegalensis and Sclerocarya birrea (7.53% each). In contrast, the South Sahelian area was dominated by L.microcarpa (12.20%), Diospyros mespiliformis (11.72%), and S.birrea (8.35%), alongside Faidherbia albida and Hyphaene thebaica (7.70% each). These findings suggest that, despite the overall diversity of species recorded, a limited group of species accounts for most of the reported uses and cultural importance, illustrating their pivotal role in household subsistence strategies and local resilience.

Table 3. Woody species providing NTFPs and their importance according to the agro-climatic area.

3.1.3. Factors Influencing Availability

As shown in , the linear regression analysis conducted on 379 households shows that the model is overall significant (p < 0.001) with a coefficient of determination R² = 0.50. Two factors appear to be decisive: the number of species collected (β = 0.117; p = 0.009), which is positively and significantly associated with the total quantity collected, and household size (β = −0.017; p = 0.015), whose slightly negative effect suggests that internal resource distribution or activity diversification may limit the quantity collected per member. Other variables (gender, education, ethnicity, land area, collection distance, climate perceptions, parasitic attacks, and collection site) have no significant effects (p > 0.05), indicating a relative homogeneity in collection behaviors.

Table 4.Factors affecting NTFP availability.

3.1.4. Factors Influencing Degradation (Logit Model)

As shown in , the Logit model applied to 379 observations is overall significant (Wald χ² (11) = 25.11; p = 0.0088) with a pseudo R² of 0.0592, indicating that the included variables explain a significant portion of the NTFPs disappearance probability. Among the variables tested, ecological area shows a significant and negative effect (β = −0.63; p = 0.025), indicating that households located in certain areas are less likely to report NTFPs disappearance.

Table 5. Factors affecting NTFPs degradation.

As shown in , the Logit model revealed a high average probability of NTFP extinction, estimated at about 71.6%. Marginal effects showed that some variables influence this risk significantly. Belonging to the northern Sahelian area reduces the likelihood of species disappearance by 13% (marginal effect = −0.130; p = 0.027) compared to the southern one. Similarly, higher education levels are associated with an 11% lower probability of extinction (marginal effect = −0.111; p = 0.066). In contrast, the number of species harvested exerts a positive effect (marginal effect = 0.024; p = 0.091), indicating that each additional species collected increases the probability of extinction at about 2.4%. This result highlights the risk of overexploitation when households diversify harvesting practices excessively, thereby intensifying pressure on natural resources. Other factors, including the gender of the household head, household size, and the distance to the collection sites, did not show statistically significant effects. Likewise, insecurity was not found to significantly influence species extinction.

Table 6. Marginal effects.

Note: (*) dy/dx is for the discrete change of the dummy variable from 0 to 1.

Results show that NTFPs exploitation is closely linked to household characteristics, with most respondents being married farmers and an average household size of around ten persons, representing both a source of labor and an increasing food demand ([10]; [7]; [30]). Beyond these socio-economic attributes, tree species play a central role in household livelihoods. The results confirm that M.crassifolia is particularly important in the northern Sahel, where it serves as both a source of food and fodder, in line with the findings of [20]. Similarly, D. mespiliformis appears more significant in the southern area, where it contributes to household income generation and provides multiple uses in food and traditional medicine, corroborating the observations of [1]. Other species such as L. microcarpa, S. birrea, and F. albida are present in both zones, highlighting their multifunctional value, while Z. mauritiana and B. aegyptiaca are also distinguished by their contribution to trading and income generation ([28]; [18]).

The linear regression result indicates that both woody species diversity and household labor determine the availability of Non-Timber Forest Products highly, supporting the evidence that in Sahel and West Africa, plant species richness enhances the access to NTFPs, improves dietary quality, and provides households with food and income opportunities ([23]). The lack of a significant effect of socio-economic variables supports ([21]), indicating that collection remains a community-based activity, largely influenced by household composition and species diversity rather than individual characteristics or land size, as also noted by [17] and [32] in Niger and the Sahel. Furthermore, local governance and community-based management practices play a crucial role in the availability and sustainability of NTFPs, as highlighted by [19] in their study on the role of NTFPs in climate action in the West African Sahel.

Logit model results reveal a high probability of species extinction (71.6%), with significant marginal effects including that households in the northern area is facing lower risk of about 13% compared to those in the south, education reduces extinction probability by 11%, while harvesting a greater number of species increases this risk fot about 2.4% ([11]). These findings suggest that simultaneous exploitation of multiple species may exacerbate the risk of overharvesting, consistent with observations that increasing reliance on NTFPs for income can exceed the regeneration capacity of the harvested species ([34]; [22]). Similar concerns have been raised in Central Africa, where unsustainable harvesting of Baillonella toxisperma wrecked both ecological resilience and local livelihoods ([25]). Overall, these results highlight a transition from socio-economic factors to ecological pressures, showing that NTFPs’ sustainability in Sahelian systems is mainly conditioned by species availability, household dynamics, and local management practices. This underlines the importance of promoting biodiversity and implementing community-based strategies, such as Assisted Natural Regeneration, to sustain natural resources and strengthen resilience ([15]; [26]).