Location of the work area

The research was carried out in the province of Cabinda, in the different places, such as: Cabassango, San Pedro, Uneca and Ngoma, Figure 1, on the date between January 2019 and October 2021 (Figure 1).

Edaphic characterization

The soils are classified as the differentiated alluvial type on carbonate transported material, with characteristics of a deep, red-yellow horizon, with excellent structure and low fertility. They were also described with a profile A, B, C, when they present transition horizons, deep, with a moderately deep brown to yellowish brown A horizon, with color 10 YR 5/8 to 7.6 YR 6/8. The clay is less than 50 % and the sand fraction acquires high values, which can vary from 30 to 60 %, where fine sand predominates and the apparent density acquires relatively high values, varying between 1.25-1.45 g/cm³, which translates into total porosity values between 60-45 % ^{(FAO, 2008)}.

The same author explains that as part of the chemical properties, in the upper horizons, the organic contents oscillate between 2.26-3.86 % and a noticeable decrease with depth is observed, slightly acidic pH between 5.5 - 6.6 and its degree of saturation ranges from 45 to 60 %.

Climatic characterization

Figure 2 represents the climatic characteristics of the Cabinda municipality, according to the meteorological station, from 2009 to 2021. The average annual temperatures are 34.58ºC and the average rainfall is 909 mm per year. The driest months are from April to the second half of October and in December, while from January to the first half of April they are rainy and November is the rainiest month, with over 100 mm. In general, it is characterized by a dry climate (Figure 2)

Determination of the use category of NTFPs

To collect this information, a questionnaire was used as a fundamental tool for collectors of NTFPs, to learn about their main uses and benefits, where different questions were asked:

At the same time, the closed questions that were used were: bivalent (they gave two possible answers, which were, obviously, exclusive and antonymous) and with exclusive alternatives (they offered several possible answers but were mutually rejected).

A pre-test was applied to a preliminary sample of 30 individuals, in order to adjust the questionnaire as explained by ^{López-Beltrán et al. (2021)}, which allowed to achieve complementary elements on the problem.

After carrying out the previous test and redesigning the questionnaire, it was applied to the determined sample through the procedure described for social studies.

In it, there are a total of 120 people (90 women and 30 men). 100 % of the people were studied, with the aim of knowing the uses and benefits of the non-timber forest products that exist in the province of Cabinda.

Ethnobotanical analysis

For the analysis of the ethnobotanical indices, the following equations recommended by ^{Tardío and Prado (2008)} and ^{López-Beltrán et al. (2021)} were used:

The Relative Frequency of Citations (FRC): its objective is to identify the species considered useful by the community (Equation 1).

Value of Use (VU): evaluates the relative importance of a species cited by the informants (Equation 2).

Ordering priority (ROP "Rank Order Priority"): used for the category of medicinal use, in which associated with the FL it presents a new level of agreement, regarding the distribution in the category of use studied, of the knowledge of the species compared to species richness (Equation 3).

Determination of the use category of plant NTFPs

Table 1 shows the forest formations of the collection, where 70 % of the population recognize the place of collection of the products and 30 % do not, in which 12 families appear, with five species of Fabaceae (Glycyrrhiza glabra L.., Epinephelus tukula Morgans 1959, Pterocarpus tinctorius Welw, Erythropleum suaveolens (Guill. & Perr.) Brenan and Burkea africana Hook.); three from Anacardiaceae (Anacardium occidentale L. Spondias mombin L. and Mangifera indica L.).

It can also be observed that two species are found: Myristicaceae (Staudita stepitata (Warb.) Warb, Pycnanthus angolensis (Welw.) Warb and Cucurbitaceae (Senna occidentalis (L.) Link and Momordica charantia L.); there are also families with one species: Zingibernaceae (Zingiber officinale Rosoe 1807); Rubiaceae (Pausinystalia macroceras (K. Schum.) Pierre Ex Bille); Chenopodiaceae (Chenopodium ambrosioides L.); Combretaceae (Terminalia superba Engl. & Diels); Moraceae (Chlorophora exceisa (Welw.) Benth); Sapotaceae (Baillonella toxisperma Pierre); Myrtaceae (Psidium guajava L.); Meliaceae (Azadirachta indica A. Juss) (Table 1).

In the study, it was noted that ten species are from the evergreen humid dense forest formation (Maiombe), ten belong to the shrubby savannah formation, and two are from the semi-deciduous humid dense formation (low Maiombe). This indicates that most of the NTFPs come from formations that have excessive exploitation for wood and affect these products.

Similar results coincide with ^{León-Merino et al. (2017)} when affirming that when forests and savannahs are properly managed, they provide products and services in a sustainable way. However, when this is not done, the rate of deforestation and degradation thereof increases, through indiscriminate logging, degradation of the ecosystem and affectation of the soils.

The natural resource that is most extracted in Angola is forestry. That is in correspondence with ^{Malengue (2019)} who states that the existence of greater logging, causes many non-timbers forest products to be little used.

It can be seen in table 2, the purpose of use and medicinal indications of the species, where 88 % of people recognize it and 12 do not, which explains that, among the species, 17 are medicinal, 11 used as fuel and nine belong to the food category, one to condiment, six artisanal and five provide shade. Several medicinal indications are also shown, in which five are used for diarrhea, three based on malaria, one without medicinal indications and the rest have various forms of treatment (Table 2).

In the table 3, the way of preparing the products and the used part of the species is observed, where 92 % of people recognize it and 8 % do not. In addition, 15 are consumed as tea, four raw, six in syrup, two in powder, five for bath and four cooked. Moreover, the most used parts of the different species are: roots, leaves, fruits, seeds, stem and bark.

The results show that the medicinal category is the most representative, when relating to ^{Téllez-Velasco (2018)}, who report that human beings use plant species for the evaluation and treatment of their diseases in all cultures since Antiquity, by bringing the knowledge of their ancestors about medicinal plants.

Generally, the production of medicines is done by residents who learned through the knowledge inherited from their parents and grandmothers, stories that correspond to ^{Sarmiento et al. (2017)}, where they say that the collection of parts of the plants for medicinal use is done whenever it is needed to meet orders or for consumption by people from the community (Table 3).

The predominant form of preparation was tea, from the leaves and peels of various species such as: Glycyrrhiza glabra, Zingiber officinale and Pausinystalia macroceras and there are different ways of obtaining: the leaves from Azadirachta indica are removed and boiled, then they are cooled off for ten minutes for typhoid treatment. The peel of Pausinystalia macroceras is also boiled for treating dysfunction and the stem of Epinephelus tukula is left to dry, then it is turned into powder for traditional rituals and beauty treatments.

These results coincide with ^{Tardío and Prado (2008)} who explained that the forms of preparation also have great importance in an ethnobotanical survey, in this study, the forms of preparation found were: syrup, bath, tea, macerated powder, raw and cooked.

According to the interviewees, the knowledge of the use of the plants is based mainly from father to son (vertical sense), due to the exchange of information between the neighbors (horizontal sense), mainly when it comes to medicinal species and even by simple observation, when corresponding with ^{Jiménez et al. (2018)}, who talk about the most used part of the plant (roots, leaves, seeds, peel, stems and fruits), in order to help low-income rural and urban communities.

In table 4, the current occurrence of plant species is observed, where 44 % are large, 35 % medium and 21 % small, which of the 21 species: 13 are large (arboreal), six medium (shrubs) and one small (herbaceous) (Table 4).

The results show that the most used NTFPs are the arboreal type, coinciding with ^{Aguirre and Aguirre (2021)}, who explain that the organs used are flowers, fruits, peels, roots, leaves and seeds available in a certain season of the year.

In rural communities, NTFPs are a form of self-subsistence, which is in correspondence with ^{López-Beltrán et al. (2021)} that demonstrate the great importance of products for the rural and regional economy, as well as the important role in culture, identity, folklore, local spiritual practices. Besides, NTFPs provide rural communities with vital resources such as medicines, food, shelter and source of income.

Table 5 shows the perception of the plant and times of collection of NTFPs, where 93 % do not recognize their perception but seven do. While 45 % collect it in the rainy season, 55 % do it in the dry season, which shows that 15 species are collected in the rainy and dry season, only three in the dry season and two during the rainy season (Table 5).

Most of the NTFPs are collected in the rainy and dry season, according to the characteristics of each species in the area. These results coincide with ^{Zamora Martínez (2017)}, who affirms that the harvest of goods and services is within the limits of productivity of the system, of the capacity of support and of its level of guarantee of the permanent operations in the ecosystems.

These results suggest that Glycyrrhiza glabra, Zingiber officinale Pausinystalia macroceras, Azadirachta indica and Momordica charantia are species of high value for the local community, and these results coincide with ^{Aguirre et al. (2019)} when stating that these products are among the most mentioned in studies carried out in different communities.

Figure 3 shows the relative frequency which allows knowing the management and conservation of the species, from the importance of their uses. That is in correspondence with what was indicated by ^{Sánchez et al. (2020}), who explained that, with the values achieved, these species provide quality of life for families under various aspects and diversity of use (Figure 3).

Figure 4 shows the use value of the species, where the species with the highest use value are shown: Pausinystalia macroceras, Anacardium occidentale and Staudita stepitata. Since the ethnobotanical study is the first multidisciplinary step, it allows ecophysiological knowledge, to assist in the management and conservation of species from the importance of their uses, according to ^{González et al. (2017)}, which agrees with the values achieved, where these species contribute to improving the quality of life of these families under various aspects and with a diversity of use (Figure 4).

Figure 5 shows the absolute frequency of the species by category of use, where it is identified that there is a greater predominance of medicinal and fuel, coinciding with these results ^{Téllez-Velasco (2018)}, explaining that the communities have extensive knowledge regarding the use of species, in addition to their relationships and cultural practices they have regarding the care of the forest (Figure 5).

Also in correspondence with these results are ^{Jiménez et al. (2018)}, making it clear that the high value of rural communities for NTFP species is due to several factors: the low income of these populations, the distance from the urban area, inefficiency, and the cost of river transportation.

Figure 6 shows the ordering priorities, where the results show that the highest values are concentrated in Glycyrrhiza glabra (indicated in Anti-inflammatory treatments), Pausinystalia macroceras (treatment of sexual impotence), Zingiber officinale (treatment of joints and digestive system) and Azadirachta indica that treats cavities, stomach aches and malaria.

These results correspond to what was obtained by ^{León-Merino et al. (2017)}, who affirm that all the wealth of knowledge regarding the therapeutic use of traditional plants by the populations originates in the need for an alternative therapeutic treatment. That, in many cases, is due to low incomes in contrast to the high prices of pharmaceutical medicines, because of the limited access to public health and the great cultural influence.