1. Introduction
The protected area approach to biodiversity conservation has been claimed to be an efficient and effective strategy under the scenario of limited conservation resources. However, the sustainability of its outcome in biodiversity conservation has generated polarized scientific opinion [
1]. Different global assessments of the performance of protected areas have suggested that the majority of strictly protected areas are a failure—both in terms of ecological and social output [
2]. The challenge for the sustainability and effectiveness of the protected area approach, in part, lies in its management strategy that often tries to solve biodiversity conservation challenges as purely an ecological problem [
3]. It fails to address competing social demands [
2] and often considers local people as part of the problem of biodiversity loss, not part of the solution [
4]. This contravenes the long-held belief that people have used traditional socio-ecological knowledge in managing landscapes since time immemorial.
Traditional socio-ecological knowledge (TSEK) is an adaptive and complex system of experiential knowledge, practices, and beliefs of local people, governing relationships among themselves and with their surrounding ecosystems. Using this complex set of TSEK, local people have been making various land-use management decisions to obtain multiple benefits in their landscape. These include the delimitation of areas of the common resource use zone, culturally protected areas/sacred forests, the protection of rare species and the rotational resource/successional management of vegetation [
5]. By doing so, local people have been reconciling their livelihood demands with biodiversity protection, sustainably. The knowledge, innovation and practices of such communities have been co-evolving to adapt to the changing environmental, political and socio-economic changes [
5,
6], through trial and error over time [
5]. The legacy of pro-environmental cultural values and traditional conservation practices still exists in many parts of the world [
7]. Nonetheless, there has been disagreement surrounding the validity of such claims.
For instance, Low [
8] highlighted that local people’s resource use behavior is ecologically driven, based on an abundance of resources. It does not correlate with attitudes involving compliance with sacred protection. According to Low [
8,
9], the low impact on their environment is often not a result of a collective conscious effort to conserve their natural resources. Local people do not willingly sacrifice short-term benefits with the expectation of a greater common good in the long run. The low impact is purely due to a combination of low population density, inefficient extraction technology, and a lack of profitable markets for extracting products. With their recent meta-analysis, Gonçalves et al. [
10] appear to partly support Low [
8] in that there exists a correlation between the abundance of a species and the overall use values of the species. The correlation between the use value of a species and the specific category of utility was inconsistent. The utilities included fuel wood, construction materials, livestock grazing and browsing, wild food, and traditional medicines, factors which are important for the maintenance of rural livelihood.
Contrary to Low [
8] and Gonçalves et al. [
10], the recent study by Soares et al. [
11] suggests that cultural factors play a predominant role over ecological factors in driving plant use and knowledge. The abundance of a species or the relative ecological importance of a species does not correlate to use value. One of the possible explanations for the lack of consistent conformity of abundance as a driver for human use behavior in Gonçalves et al. [
10] could be due to the mismatch of the theoretical basis of most of the studies to actual human behavior. Most of the ethnobotanical studies were conducted using the “ecological appearance hypothesis”, which was formulated by Fenny [
12] and Rhoades and Cates [
13] for a different ecological question. The original intention of the hypothesis was to test if plant species that are visible and abundant are more susceptible to herbivory [
14]. Unlike free grazing in herbivory, local communities design cultural institutions and social norms (e.g., traditional bylaws, rituals, and ceremonies) to regulate access and to sanction appropriate corrective measures when contravention to the governing rules of common resources is detected [
7].
The above disagreement hints at the complexity of human behavior in managing relations among themselves and with surrounding ecosystems. The inherent assumption of the ecological appearance hypothesis is that individuals in society are rational and efficient in their choice of a species for various utilities [
15]. This assumption is too simplistic to predict the human use behavior of communal resources. Human behavior is also influenced by cultural institutions and social norms [
7]. Those cultural institutions and norms do not only govern the behavior of individuals towards a specific species (e.g., species-related taboos and totems); they also govern collective behavior towards the whole biodiversity of a landscape by using a complex set of TSEK and habitat-related taboos. However, the question of how these cultural institutions and norms determine the spatial distribution of land use intensity across different spatial hierarchies of a landscape has not been adequately researched [
16]. Land use intensity has been suggested to be a good predictor to explore the relationship between culture and biodiversity, since it is often reciprocally affected by both over space and time [
17].
Moreover, all people have culture that governs their relationship with their surrounding ecosystems. It is often easier to grasp the influence of different people’s cultures on environmental behavior when the lifestyles of groups are markedly distinct from each other [
18]. At the same time, every landscape has a peculiar spatial heterogeneity of ecological resources, which has been shaped either by natural forces, cultural disturbance, or both [
19]. Jointly, the aforementioned arguments imply that there is a need to study individuals and communities from a homogenous cultural group who reside in different forest landscapes in order to determine the factors that play a predominate role in use behavior. Thus, the central question of this study was to test if culture and ecological abundance have equal power to explain forest and tree use behavior in local communities. To the best of our knowledge, there has not been any research to that effect. The findings from our study may provide knowledge to promote the sustainable and collaborative conservation of forest landscapes that work both for biodiversity and for local people [
20]. Based on the above arguments, we formulated and tested the following hypotheses:
Homogeneity of cultural value: communities from the same cultural group, but residing in different forest landscape conditions, demonstrate similar use behavior towards similar habitats (land use intensity), as specified by cultural institutions and social norms.
The use value gradient in the multifunctional landscape: the total use value of land use regimes in the multifunctional landscape increases with the increase of the socially perceived land use intensity gradient, both at a cultural group and household level.
Ecological appearance hypothesis: local people depend highly on the most abundant species in their landscape for various utilities [
21].
4. Discussion
Considering (i) the skepticism surrounding the sustainability and effectiveness of the existing global protected areas to safeguard tropical biodiversity [
2] and (ii) doubts about the conservation behavior of traditional society towards their surrounding ecosystem, on which they rely directly or indirectly rely for the maintenance of their lifestyle [
8,
9], empirical evidence on the drivers of natural resource use behavior are crucial. The current uncertainty about the predictive capacity of the ecological appearance hypothesis implies that the ecological resource use behavior of local people is far more complex than an exclusive association with an abundance of ecological resources. In this case study, we examine the predominance of culture in shaping forest and tree use behaviors of traditional society in human-modified forest landscapes, and we discuss their implications for the conservation of biodiversity. Our case study was performed in two Vhavenda communities who share the same culture. However, the two communities reside in forest landscapes that markedly differ in their ecological conditions (species richness, identity, and abundance) (
Section 3.1,
Table 2).
4.1. Homogeneity of Cultural Values Related to Similar Land Use Regimes in Different Ecological Conditions
The significance of culture is often easier to grasp when the lifestyles of groups are markedly distinct from each other [
18]. In hindsight, our findings on the homogeneity of use values related to similar land use regimes/habitats of local people who reside in two distinct forest landscape conditions imply that forest condition does not play a primary role in local people’s forest use behavior. Instead, considering that the two Vhavenda communities share the same culture, it highlights that the shared values and norms (a complex set of knowledge, beliefs, and practices) play a predominant role in the active use and management of their forest landscape, rather than the conditions of forest resources.
Our interpretation may appear to be at odds with the recent global assessment by Aswani et al. [
41], who highlighted that the forced displacement or significant reduction of access to cultural resources and institutional reforms are some of the critical drivers of global loss of traditional socio-ecological knowledge. Notwithstanding, the complete loss of traditional socio-ecological knowledge or a substantive shift in culturally shared values can only happen in areas where there has been a significant shift in lifestyle due to large-scale ecological devastation or the complete integration of traditional society into a market economy [
42], in an unsustainable manner. In the case of our study, although the two Vhavenda people were forcefully displaced from their landscapes like many of the historically disadvantaged communities in South Africa [
43], they still reside within the parameters of their cultural landscapes. The remaining forest and tree resources used by Vhavenda people are still intertwined into their livelihood, and into the cultural, emotional, spiritual and symbolic values of their lifestyle [
24,
25,
28]. This is not to argue that forced displacement or institutional reforms in traditional society do not affect the cultural assets or traditional socio-ecological knowledge. Instead, it is to emphasize the dynamic and adaptive nature of cultural values. Acquiring new knowledge through consistent trial and error to fit the changing social and bio-physical environment has been part of human evolutionary history [
44]. Within the range of normal cultural change [
18], a shift in cultural value proceeds incrementally and follows a predictable manner. The complete replacement of one set of cultural values in individuals, or in society, by another set of new values does not occur [
42].
4.2. Use Value Gradient Is Consistent with a Socially Perceived Land Use Intensity Gradient
Overall, our study found that the forest landscape is locally popular as a source of wild food, fuelwood, livestock grazing and browsing, construction materials, and traditional medicines, in descending order. Consistent with our hypothesis, the use value of a land use regime for those products depends on a culturally defined land use intensity gradient, with the exception of SIF, which is also embedded within the same landscapes. In conformity with traditional rules, local people largely depend on open access common resource use zones for most of the utilities to sustain their livelihood. Few individuals meet their livelihood demands for relatively less destructive resource obtainment (grazing and wild food harvesting) from trees along rivers and streams. Local people extract almost no use from traditional protected areas. In contrast, strictly state-protected indigenous forests appear to provide almost equal use value compared to the open access common resource use zones.
The case of state-protected indigenous forests may imply that the superior protection of state indigenous forests most likely enhanced the ecological abundance of resources important for rural livelihoods. Local people may not extract a large amount of forest products from state indigenous forests due to a fear of retribution in comparison with common resource use zones. However, the total use value compared with the human-modified landscapes of common resource use zones implies that its effectiveness to protect areas of high ecological importance (e.g., the abundance of species, population, or ecosystems) may not be sustained in isolation. This is not surprising considering the challenge of the enforcement of protection rules in most forest reserves in South Africa [
45].
The prevalence of the use value gradient alongside the socially perceived land use intensity gradient, in contrast with state-protected indigenous forests, suggests that tree-based traditional land use decisions or forest extractions are culturally bound and non-random. At least in the case of our study, the lower use value of trees along rivers and streams and those in culturally protected areas is a testimony against Low’s [
8] assertion that there is a lack of correlation between forest and tree species extraction and attitude (including compliance with sacred protection). Similar to our findings, Mutshinaylo and Siebert [
25] claim that in most parts where the Vhavenda people reside, certain species and components of forest ecosystems (e.g., streams and rivers) are still culturally protected due to rituals, mythical beliefs, and totems. Many studies have showed that culturally protected sites create habitats for rare and threatened species [
46]. The comparable total use value of state-protected indigenous forest with open access common resource use zones may imply neither a lack of conservation attitude on the part of local people nor the pre-dominance of abundance in governing their use behavior. Instead, it highlights that the imposition of strict protection measures based on the abundance of ecological resources, without considering the cultural values of local people, may not deter local people from breaching conservation rules.
A culturally bound society does not imply that all members of society are homogenous [
46] and have similar knowledge and attitudes towards forest and tree species uses. Still, difference in household characteristics can affect their use behavior (e.g., [
11,
15]). For instance, our study found that, while common resource use zones are accessible for use to all members of society, it was the small size households who depended more on them rather than the large size households, regardless of their gender and marital status. However, it was the reverse when it came to state-protected indigenous forests. The first case may imply that small size households may have a relatively small demand, which can easily be satisfied from the nearest common resource zone. In contrast, the married and larger households may have higher demands and larger manpower to collect forest and tree species products, even from relatively far state-protected indigenous forests. However, none of the household characteristics affect use behavior related to trees along rivers and streams and in culturally protected areas. The fact that the effect of household characteristics only manifested in common resource use zones and state-protected indigenous forests highlights that even these factors generate difference within the bounds of cultural influence. Common resource use zones are culturally considered as open access for every individual member of society, while harvesting forest products from state-protected areas is a new norm, not an exception.
4.3. The Use Value of Species and Ecological Appearance Hypothesis
Although the residents of the two forest reserves share the same culture, the overall number of useful species and their percentage out of total species richness per landscape was higher in TVFR than in MFR. This could imply that the difference in resource availability between the two forests (e.g., [
39,
40]) may have provided a different extent of knowledge base on potential uses of species, through lived experience.
Nonetheless, the mean total use value of a species and the mean use value for a specific utility remained similar in both areas (
Table 4). The most likely explanation could be that, despite the overall difference in species richness and abundance, the actual user preference for a species is not exclusively determined by the abundance of the species. For instance, the Vhavenda communities in MFR and TVFR still share five highly preferred species out of the top ten most useful tree species found in the study area (
Table 5 and
Table 6). These are
Parinari curatellifolia,
Englerophytum magalismontanum,
Syzygium cordatum, Combretum molle, and
Mimutops obovata. This implies that through traditional knowledge, there is convergence on the species preference of local people for actual use, through the different social processes. These processes include knowledge sharing through oral tradition, clan gathering, initiation schools, and apprenticeship by traditional healers [
47]. Over time, this kind of knowledge intertwines into people’s cultural and symbolic identities (cultural keystone species) [
15]. Hence, the keystone species do persist as preferred species, regardless of their abundance. For instance, despite
Parinari curatellifolia and
Englerophytum magalismontanum having lower abundance in TVFR than in MFR (
Table 2), the two species are still cited as among the most important. The same popularity was also observed for
Combretum molle and
Mimutops obovate—which are rare species in both forest reserves (
Table 4 and
Table 5). However, this does not imply that people solely rely on keystone species for their survival. Local people still use other potentially useful species depending on the local ecological conditions (e.g., seasonal availability) [
39]. Equally, even if some species are abundantly available for potential use, actual use can still be constrained by species-specific taboos [
41]. Hence, the similarity of results in terms of the correlation between species abundance and a species’ use value among the two Forest reserves is not surprising.
There was a very weak to moderate correlation (r
s = 0.30–0.50) between the local abundance of a species and the use value, both for the overall and specific utility of a species, both in MFR and TVFR. The only exception was that there was no correlation between the abundance of a species with its use value for grazing and browsing, wild food, and medicine in TVFR. Similar to our findings, many studies, for example Gonçalves et al. [
10], have reported on the inconsistent power of ecological abundance to explain human use behavior in relation to overall forest utilities or specific utilities. In some recent studies, for instance Soares et al. [
11], it has been shown that ecological abundance does not explain use behavior at all.
5. Conclusions
The response to the question of whether local people consciously manage forests and tree species diversity in their landscape relies on our understanding of how culture and ecological abundance influence resource use behavior. Based on our findings, at least in the case of the Vhavenda people, culture plays a predominant role in explaining use behavior. Abundance may play a secondary role, subject to cultural context. Our findings have serious implications for the design of conservation interventions that work both for people and for biodiversity.
Unlike the exclusionary protected area approach to preserve a particular biodiversity hotspot, traditional society manages the sustainability of local biodiversity as a socio-ecological system, on which their livelihood and their cultural, emotional, spiritual and symbolic lifestyle values depend. In a forest landscape, neither land use nor resource use decisions are random decisions, nor is the concept of protected areas new to traditional society. Traditional society applies dynamic and adaptive socio-ecological knowledge systems (beliefs, knowledge, and practices) relating to a particular habitat or species as an integral part of managing the delicate balance of “use–protection” regimes, at a landscape level. The protection of sacred forests and habitats and species-related taboos are typical examples of how traditional society still consciously manages landscape multifunctional purposes. Hence, the adherence to social norms and taboos, combined with the resilience of traditional socio-ecological knowledge in human-modified landscapes, presents potential tools to complement the state and conservation agency-led protected areas. Global biodiversity conservation efforts can capitalize on the benefits of the cultural assets of local people through genuine partnership and empowerment, which can play a significant role in averting a biodiversity crisis.