Rangeland Ecology Research Articles

Grass-livestock interaction: a critical review of current research progress

IntroductionGrass-livestock interaction is of great value in maintaining ecological balance, regional economic development, and the sustainability of grassland husbandry, which has gained attention in recent years in both academia and practice, however, study on grass-livestock interaction possesses cognitive bias and gaps.MethodsThis study clarified the latest research progress and development trend in the grass-livestock interaction field by illuminating publication trend, cooperative network, keyword co-occurrence relationship, keyword clustering during 2000 to 2022 based on the Web of Science core database.ResultsThe results indicated that the annual number of publications in the grass-livestock interaction field showed a globally increasing with interdisciplinary and international collaboration, and the United States of America ranked firstly, followed by Brazil, England, Australia, China. Agricultural Research Service, the U.S. Department of Agricultures was the organization with the highest number of publications, and Rangeland Ecology & Management, Agriculture, Ecosystems & Environment, Grass and Forage Science were the top three journals. Furthermore, in terms of the temporal evolution, the research targeting the grass-livestock interaction mainly went through three stages: initial exploration period (2000–2011), to the period of rapid development (2012–2016) to transitional development period (2017–2022), and the notable existing keywords was Management, Livestock, Cattle, Vegetation, Growth, Soil. In terms of the structural composition, four broad divisions including mechanism of human activities, grassland resource monitoring and management, grassland livestock competition/adaptability, grassland land/soil research were identified. The results provide positive and objective insights into that grassland sustainability and grazing control through strengthening cross-disciplinary and cross-regional cooperation, and applying of standard methods based on evaluation system in the grass-livestock interaction field.DiscussionThe overall contribution of the work is provision of novel insight into the intellectual structure and temporal progression of grass-livestock interaction research at a macroscopic scale and the directions in which the field is headed currently.

Greater sage‐grouse chick mortality risk relative to livestock grazing management, environmental factors, and morphometric measurements

AbstractGreater sage‐grouse (Centrocercus urophasianus; sage‐grouse) populations in the western United States have declined, necessitating conservation efforts. The United States Department of Agriculture Natural Resources Conservation Service and livestock producers implemented the Sage Grouse Initiative (SGI) to improve sage‐grouse habitat using regional‐specific management actions such as rotational grazing. We assessed the effect of SGI grazing management, the influence of brood female and chick morphometric traits, and multiple environmental and anthropogenic disturbance factors on chick mortality risk in a sage‐grouse population in central Montana, USA, from 2011–2019. We used a Kaplan‐Meier survival function to evaluate chick survival, Cox proportional hazards models to evaluate chick mortality risk as a function of brood female and chick morphometric traits, and the Andersen‐Gill formulation of the Cox proportional hazards model to assess the effects of time‐dependent habitat characteristics on chick mortality risk. Survival to 45 days post‐hatch for 510 chicks varied annually from 0.26 ± 0.07 (SE) to 0.69 ± 0.07. The 45‐day survival rate for all years combined was 0.51 ± 0.03. Chick mortality risk was not affected by changes in livestock grazing management implemented through the SGI grazing program. Brood female age and body condition, sex of chicks, vegetation, and anthropogenic variables were also unassociated with chick mortality risk. There were small protective effects of chick mass adjusted for age and mean minimum monthly temperature; greater chick mass and lower monthly temperatures correlated with reduced mortality risk. Overall, our study suggests the SGI grazing program does not confer additional benefits to sage‐grouse chicks beyond existing grazing practices. Incentivizing grazing practices that adhere to fundamental principles of rangeland ecology and maintain intact rangelands may be more effective than specific prescribed grazing systems for sage‐grouse conservation in this region.

Reflexivity, embodiment, and ethics of care in rangeland political ecology: reflections of three feminist researchers on the experience of transdisciplinary knowledge co-production

Although there is a growing interest in transdisciplinary knowledge co-production approaches applied to rangeland political ecology, the research paradigms and methodologies still dominating this field of research leave little room for equitable engagement with research participants and genuine action-oriented research. In this article, we provide a reflection on new practices grounded in feminist studies of science and care ethic literature to orient transgressive and engaged transdisciplinary political rangeland ecology research. Feminist epistemologies call for reflection on who produces knowledge and how such knowledge is used and shared. Feminist practices, such as reflexivity, embodiment, reciprocity, and care, cultivate awareness of the power dynamics embedded in the research process and motivate researchers to counteract asymmetrical or extractive relationships when we identify them. We first introduce the scholarship that inspires key principles of our feminist research approach and then reflect on our experiences as researchers and as activists working with Spanish and Catalan networks of women pastoralists. Three research questions guide our reflective process: (i) how can feminist theories of knowledge co-production contribute to rangeland political ecology; (ii) how can feminist methodologies be applied in practice so that collaboration between women pastoralists, their organizations, and researchers is mutually reinforcing, care-full, and action-oriented; and (iii) what are the challenges and limitations of our experiences to foster transformation and emancipation in knowledge co-production processes?

A Revised Adaptive Decision-Making Framework for Rangeland Management

Rangelands across the world are facing rapid and unprecedented social and ecological change. In the US West, sustaining the ecological and economic integrity of rangelands across both public and private lands depends largely on ranchers who make adaptive decisions in the face of variability and uncertainty. In this study, we build on previous conceptualizations of adaptive decision making that situate individual-level decisions within complex rangeland social-ecological systems. We surveyed 450 (36% response rate) Montana ranchers to gain insight into how key factors influenced adaptive decision making, specifically in the context of ongoing drought and climate-related change affecting rangeland ecology and productivity. We predicted that ranchers’ management goals, their use of information sources, and their use of monitoring would significantly influence the use of adaptive practices, with monitoring mediating the relationship between the explanatory and response variables. We tested these predictions using a path model analysis and found that management goals related to both stewardship and profit/production, the number of information sources used, and monitoring were all significantly and positively related to ranchers’ use of adaptive management practices. Interestingly, we found that these factors were hierarchical with monitoring and the use of information was the strongest predictor while management goals were secondary. The significant, mediating effect of monitoring on the use of adaptive practices suggests that monitoring may be an important means for providing ranchers with useful and timely information about rangeland condition that is needed to adjust their actions, meet their management goals, and adapt to drought and climate-related change. We argue there is a need to better understand the efficacy of monitoring designs—of what, by whom, and how—for adaptive decision making, and we discuss other considerations related to the provision of useful drought and climate information for adaptive decision making based on our findings.

Reframing rangeland systems science research in Kenya: a synthesis of social-science mixed methods to inform integrative analysis of landscape pattern and process

ContextInterdisciplinary borrowing between ecology and the social sciences has produced numerous insights about pastoral livelihood practices and rangeland ecology, demonstrating how people practicing pastoralism constantly modify their practices to adapt to social, political, economic, and biophysical change.ObjectivesI outline an approach for integrating research on pastoral livelihoods into a landscape ecology framework. I focus on access to land and resources, and an integrative approach to scale, to assess the relationship between landscape and social processes.MethodsI use remotely sensed data and ethnographic analysis of livelihood change in two semi-arid contexts in Kenya to compare broad scale changes in pastoral mobility to spatio-temporal patterns of variability in rainfall and vegetation productivity. I then synthesize the political, economic, and social relations that have most prominently influenced access to land and restructured landscape process at finer scales.ResultsSpatial controls have been imposed on land use that have increasingly partitioned landscapes and concentrated pastoral access to land. Access to land has also been influenced by changes in social norms, employment, and market relations. Informal rules and norms, social differentiation, and exclusionary partitions have produced socially differentiated land use intensity gradients and novel landscape processes that have not previously been considered in landscape analyses in Kenya.ConclusionsUnderstanding access, land use, and landscape processes as intertwined, with uneven processes of land and resource capture at different scales, would enable landscape ecologists to choose observational scales relevant to rural livelihoods and sensitive to power asymmetries, creating robust analytical linkages between social and ecological processes.

Cheatgrass: Fire and Forage on the Range. By James A. Young and Charlie D. Clements

James A. Young and Charlie D. Clements, two scientists from the Agricultural Research Service of the U.S. Department of Agriculture, invite readers to reflect on the history of cheatgrass and its management in the Great Basin. The authors state that the purpose of this book is to inform the public and other rangeland managers about the flaws of past cheatgrass management and to offer suggestions for handling the plant communities of the Great Basin. While the book has several glaring problems as both a history and a call-to-action for federal land agencies, this helpful narrative of federal weed management in the twentieth century can still be utilized by environmental and agricultural historians. Cheatgrass is both an attempt to explain the landscape history of the Great Basin region and the evolutionary and cultural history of cheatgrass. The book is organized into seventeen thematic chapters that cover a range and variety of topics from the phenotypic plasticity of the plant to cultural perceptions about it and its role in rangeland ecology. These chapters are not uniform in their intended audience or purpose, leaving the reader with a sense of stylistic and argumentative disjuncture. At times the authors address federal land managers and the overgrazing of the range in the Great Basin using scientific language. Other chapters take issue with environmentalists and the stigma against using widespread herbicides to convert cheatgrass-invaded areas to crested wheatgrass. Additionally, Young and Clements attempt to use anecdote and historical examples to support their arguments but fail to cite any serious scholarship in the fields of environmental or agricultural history. What this book lacks in argument is made up for in its knowledge of twentieth-century range and weed science.

Understanding the impact of climate change and resilience among highlanders in northern parts of Bhutan: A case study in Gasa district

Mountainous regions are affected the most by climate change across the world. The livelihood of highlanders primarily depends on livestock farming and natural resources. In Bhutan, yak farming and sale of Cordyceps sinensis (caterpillar fungus)remain the main source of income for most highlanders. We conducted a study to understand the impact of climate change on the community livelihoods in Bhutan. A cross-sectional survey was conducted and interviewed 132 household heads, two focus group discussions of 20 respondents (10 in each group), and key informant interviews (n = 5) in two highland communities (i.e., Laya and Lunana) of Gasa district in northern Bhutan between August 2019 and February 2020. The study revealed that the caterpillar fungus (78.8%) is the major source of income for highland communities which overtook the yak farming practices since its legalization in 2004. More than 80% of households have abandoned yak farming due to its poor economic return because of the decreased utility of yak for meat purposes and other socio-cultural related practices. The majority of the respondents (91%) expressed concern that climate change is posing a threat to the growth and subsequent harvest of caterpillar fungus. The highland people reported emergence of insects/vectors in their community and mosquitoes were the most frequently reported (85%) insect. A small proportion of respondents (1.5%) were concerned about the grazing habitat of the yaks due to the change in the botanical composition of the rangeland. Given that there is a decrease in caterpillar fungus, which is the main source of income for highland communities, this study calls for a climate-resilient community-based economic opportunity for the sustainable livelihood of highland communities. Furthermore, we recommend a detailed study of the negative impacts due to climate change on freshwater resources, the distribution of vectors and vector-borne diseases, and rangeland ecology in the highland.

Table of Contents

The Rangeland Journal publishes papers of scientific merit for a readership of scientists, educators, managers and users. Contributions may be on any aspect of the ecology, use, management or conservation of rangelands, either within Australia or internationally.

Rangeland Degradation and Its Impacts Post-1992: Constructing the Perceptions of Boorana Pastoralist, Southern Ethiopia

The rangelands of Africa have been subject to substantial changes. The changes in the savanna rangelands ecology were often assessed from different points of view. This study constructs the perceptions of Boorana pastoralists on historic changes in rangelands post-1992 based on the Gadaa timelines. The construction of pastoralist perceptions can make an immense contribution to comprehending the rate, trends, indicators, and impacts of rangeland degradation in Boorana rangelands. This study thus points out that pastoralists can better understand and describe rangeland conditions and factors associated with such changes in the Gadaa periods. The study was based on the data collected from 332 pastoralists using a survey questionnaire and qualitative data, and the results were analyzed using descriptions of responses and narrations of cases. The study revealed that the conditions of the Boorana rangelands have been deteriorating over time and rangeland degradation showed unprecedented growth trends, mainly attributed to vegetation, rangeland production, human, environmental, and climate change-related factors. The study also shows that the progressive degradation of rangeland resources has jeopardized rangeland production, livestock productivity, and human well-being in the Boorana rangeland system. The study suggests that the recognition and promotion of indigenous ecological knowledge of pastoralists could sustain the pastoralist community in arid and semiarid rangelands. It is, therefore, imperative to understand pastoralists’ knowledge of rangeland ecology for sustainable management of rangeland resources.

Table of Contents

The Rangeland Journal publishes papers of scientific merit for a readership of scientists, educators, managers and users. Contributions may be on any aspect of the ecology, use, management or conservation of rangelands, either within Australia or internationally.

Does the landscape functionality approach provide insight into rangeland conditions in the Tanqua Karoo region, South Africa?

The harsh environmental conditions coupled with a long history of overgrazing have altered the ecology of the arid Tanqua Karoo rangelands in South Africa, which necessitates rehabilitation. However, a suitable method for monitoring rangeland function over time is required for sustainable management. In this study, vegetation characteristics and landscape function indices were used to rate and compare rangeland conditions in 43 sites distributed among three vegetation types: Tanqua Karoo, Tanqua Wash Riviere, and Tanqua Escarpment Shrubland, which occupy different landscapes in the Tankwa Karoo National Park. The results showed low values of vegetation volume (mean of 10.1 m3 per 100 m−2) and low vegetated patches (mean of 29% patches vs 71% fetches). The overall landscape function indices (soil stability, water infiltration, and nutrient recycling) were low and amounted to 55%, 28%, and 17%, respectively. Amongst the various examined landscapes, the escarpment had the highest values of most of the measured landscape functionality parameters, and the open plains had the lowest values. This revealed high heterogeneity of soil properties and vegetation characteristics amongst the different vegetation types, mainly influenced by altitudinal gradients. The higher-lying landscapes on the escarpment are relatively more functional and more susceptible to improvement when compared to the lower-lying landscapes on the plains. The landscape functionality approach (LFA) approach demonstrated that some of the examined vegetation types had insignificant improvement in landscape functionality likely not to improve in the near term due to existing low patchiness, higher fetch space and low LFA indices coupled with the low annual rainfall of the region. The landscape functionality approach has provided a suitable benchmark for assessing and monitoring the diverse vegetation types in this arid part of the world.

Table of Contents

The Rangeland Journal publishes papers of scientific merit for a readership of scientists, educators, managers and users. Contributions may be on any aspect of the ecology, use, management or conservation of rangelands, either within Australia or internationally.

Goat browsing does not induce physical defences but reduces leaf size in Vachellia trees

One aspect of plant-herbivore interactions in African savannas is the browsing impact of mammalian herbivores on plants, which may result in induced physical defences (spines) and changes in leaf morphology in trees experiencing intensive browsing. In these savannas, spinescence is considered to have evolved in response to herbivore pressure from large mammals. We assessed the impact of free-ranging domesticated goats on the spines and leaves of Vachellia karroo, V. nilotica and V. tortilis in Msinga, South Africa. We predicted that there would be fewer and smaller leaves, and longer spines occurring below compared to above 1.5 m for all tree species. We further predicted that the outer parts of the tree canopy would have smaller and fewer leaves, as well as more and longer spines compared to the inner part of the canopy. To determine the response of these trees to goat herbivory, 35 trees of each Vachellia species were selected, the number of leaves and spines found on two randomly selected branches below 1.5 m and one above 1.5 m were measured. We found that leaves were fewer and smaller below compared to above 1.5 m. Interestingly, we found the reduced leaf size to be equal to the size of spines below 1.5 m. We also found that V. karroo had more spines below 1.5 m compared to V. tortilis and V. nilotica. Along the branch segments, we found that spines were longer in the most accessible parts of the branch, the outer canopy. This study showed that browsing by goats, unlike wild herbivores, do not induce plant physical defences but rather limit available foliage. We also showed that physical defences (spine density) of Vachellia trees vary. This has implications for management and ecology of rangelands browsed by domestic mammals.

Fortifying the financial and environmental capital banks in commercially grazed rangelands

Commercial rangeland livestock producers manage a perpetual conflict. They must ensure that the financial and environmental elements of rangeland grazing remain concurrently robust, with neither borrowing excessively from the other. Successfully managing this financial and environmental tension requires sound financial literacy as it applies to pastoralism, an above-average knowledge of rangeland ecology, and intellectual and practical management skills. Achieving these competencies is the starting point for a truly sustainable rangeland grazing business. The degree to which these competencies are achieved is largely under the control of the people who manage the business. However, there are significant external influences that can impede progress towards better financial and environmental outcomes. In this paper, we draw upon more than 50 years of combined professional experience to present our definitions for financial and environmental sustainability, as they pertain to northern Australian grazing enterprises. We summarise what is currently known about the financial and environmental performance of the northern Australian beef industry, and highlight some of the current external factors that are potentially antagonistic to achieving sustainable livestock production. We conclude with a protocol that our most successful clients have used to achieve (and demonstrate) financial and environmental sustainability.

Using Hyperspectral Imagery to Characterize Rangeland Vegetation Composition at Process-Relevant Scales

Rangelands are composed of patchy, highly dynamic herbaceous plant communities that are difficult to quantify across broad spatial extents at resolutions relevant to their characteristic spatial scales. Furthermore, differentiation of these plant communities using remotely sensed observations is complicated by their similar spectral absorption profiles. To better quantify the impacts of land management and weather variability on rangeland vegetation change, we analyzed high resolution hyperspectral data produced by the National Ecological Observatory Network (NEON) at a 6500-ha experimental station (Central Plains Experimental Range) to map vegetation composition and change over a 5-year timescale. The spatial resolution (1 m) of the data was able to resolve the plant community type at a suitable scale and the information-rich spectral resolution (426 bands) was able to differentiate closely related plant community classes. The resulting plant community class map showed strong accuracy results from both formal quantitative measurements (F1 75% and Kappa 0.83) and informal qualitative assessments. Over a 5-year period, we found that plant community composition was impacted more strongly by weather than by the rangeland management regime. Our work displays the potential to map plant community classes across extensive areas of herbaceous vegetation and use resultant maps to inform rangeland ecology and management. Critical to the success of the research was the development of computational methods that allowed us to implement efficient and flexible analyses on the large and complex data.

Curbing overstocking on rangeland through subsidies, rewards, and herders’ social capital: Lessons from Qinghai province, China

Restoring rangeland ecology, a goal set by the Rangeland Ecological Protection Subsidy and Reward (REPSR) scheme of China, depends on how effectively livestock overload can be curbed. Besides subsidies and rewards, herders' individual social capital also bears an important weight on their willingness to lower stocking rate. Social network offers an invisible conduit for herders to build up social capital, thus quantifying social capital through social network analysis is more straightforward than simply using proxy indicators, an approach commonly adopted so far. Based on a questionnaire survey on 288 households in Qinghai province, the effects of social capital and the REPSR compensation on stocking rate are empirically examined, replacing the traditional proxies of social capital with herders' ability to obtain information and resources as well as the restrictions imposed by social norms from social networks. Social capital is found to have a statistically significant impact on stocking rate, but tradeoffs exist among various network pathways. Herders’ acquisition of policy information and stall-feeding skills through social networks contributes to lower stocking rate, but acquisition of grazing experience, funds and machinery service exerts counteracting effects. A U-shaped relationship occurs between stocking rate and compensation amount offered by the REPSR: with the increase of compensation amount, herders lower stocking rate first and then increase it. To improve the effectiveness of the REPSR scheme, a refinement on the compensation scheme tailored to differential scales of household rangeland operation is the key, meanwhile weaving and harnessing social network to improve policy publicity and enforcement as well as knowledge sharing and production cooperation between herdsmen also deserve more attention.

The Society for Range Management: Bridging gaps and setting directions

• The Society for Range Management and the profession of rangeland ecology were founded about 80 years ago to bring scientific information to the management of rangelands. Sustaining a strong connection between science and management set the foundation for the rangeland profession, though this connection has been challenging to sustain. • An era of collaborative research and conservation has fueled projects that include a diversity of individuals and organizations and confirm the importance of information from both experimentation and experience. • Successfully addressing contemporary challenges to rangelands will depend on old-fashioned actions like conversation, a commitment to rangelands communities and landscapes, and engaging a wide variety of backgrounds and experiences to find solutions.

Effects of large herbivore grazing on relics of the presumed mammoth steppe in the extreme climate of NE-Siberia

The Siberian mammoth steppe ecosystem changed dramatically with the disappearance of large grazers in the Holocene. The concept of Pleistocene rewilding is based on the idea that large herbivore grazing significantly alters plant communities and can be employed to recreate lost ecosystems. On the other hand, modern rangeland ecology emphasizes the often overriding importance of harsh climates. We visited two rewilding projects and three rangeland regions, sampling a total of 210 vegetation relevés in steppe and surrounding vegetation (grasslands, shrublands and forests) along an extensive climatic gradient across Yakutia, Russia. We analyzed species composition, plant traits, diversity indices and vegetation productivity, using partial canonical correspondence and redundancy analysis. Macroclimate was most important for vegetation composition, and microclimate for the occurrence of extrazonal steppes. Macroclimate and soil conditions mainly determined productivity of vegetation. Bison grazing was responsible for small-scale changes in vegetation through trampling, wallowing and debarking, thus creating more open and disturbed plant communities, soil compaction and xerophytization. However, the magnitude of effects depended on density and type of grazers as well as on interactions with climate and site conditions. Effects of bison grazing were strongest in the continental climate of Central Yakutia, and steppes were generally less affected than meadows. We conclude that contemporary grazing overall has rather limited effects on vegetation in northeastern Siberia. Current rewilding practices are still far from recreating a mammoth steppe, although large herbivores like bison can create more open and drier vegetation and increase nutrient availability in particular in the more continental Central Yakutian Plain.

Anthropogenic erosion-induced small-scale soil heterogeneity in South African rangelands

Land-use-induced soil erosion in semi-arid drylands induced by land-use changes creates patchworks of soils and vegetation different from those of natural conditions. Knowledge of the highly dynamic spatial heterogeneity in soil properties, not depicted in conventional soil maps, is important for managing land uses sustainably, and for understanding soil-climate interactions. This analysis of soil redistribution in a degraded rangeland in South Africa assessed the significance of anthropogenic soil heterogeneity within a small catchment with a silted reservoir. This study carries out analysis of soil redistribution in a degraded rangeland in South Africa, to assess the significance of anthropogenic soil heterogeneity within a small catchment with a silted-up reservoir. Surface soil (N = 51) and soil profile (N = 29) samples were collected from areas of various degrees of degradation and analysed for texture, pH, total nitrogen (TN), total organic carbon (TOC), available phosphorus (P), and potassium (K). Diverse vegetation cover is reflected in a high soil heterogeneity, showing differences in soil texture. Average surface soil nutrient content was significantly higher in vegetated areas (grassland: TOC 1.08 %, TN 0.10 %, P 20.12 mg kg −1 , mixed vegetation: TOC 0.93 %, TN 0.08 %, P 13.54 mg kg −1 , depositional: TOC 1.68 %, TN 0.18 %, P 34.67 mg kg −1 ) than at degraded sites (TOC 0.47 %, TN 0.06 %, P 7.52 mg kg −1 ). K content was low to moderate but did not show any significant difference between landscape units. Potential exists for the formation of distinct young anthropogenic soils on the silted-up reservoir where deposited sediments differed in TOC, TN, P, and profile depth from the shallow natural soils. Consequently, azonal soils on dam-deposits are different from those occurring naturally, and not depicted on conventional soil maps. Their different water and nutrient cycling may affect vegetation and biogeochemical fluxes. Land-use management should consider such soils, as they play an important role in rangeland ecology.

Indigenous knowledge of South African bird and rangeland ecology is effective for informing conservation science

South Africa's communal rangelands constitute ~25% of the country's land cover and are largely managed for livestock grazing. These habitats play an important role in rural livelihoods and cultural practices. Using semi-structured interviews, we documented indigenous local ecological knowledge (LEK) held by rural dwellers linked to natural resource utilisation, environmental health and cultural keystone indicator species (CKIS) in the grassland communities of southern KwaZulu-Natal, South Africa. Our main objective was to examine the ability for LEK to inform conservation management. We found that people who were heavily reliant on natural resources attained a higher LEK score, indicating a greater breadth of ecological knowledge, which in turn shaped their perceptions of environmental change. Community members confirmed the presence of conservation concern species within this area, highlighting the limitations of only using citizen science databases for conservation management, as their observations within these databases are biased towards major road routes and protected or urban areas. LEK can play an important role in identifying habitats crucial to species' persistence and delineating population trends over time. Our surveys highlighted the importance of the Southern Ground-hornbill Bucorvus leadbeateri as a CKIS that acts as an early warning system of changing weather, notably rain. However, LEK is context-specific, and some CKIS species such as the Southern Ground-hornbill have wide distribution ranges. Consequently, the cultural associations and implications differ based on local belief systems that are often defined by the language spoken and the community's geographical location. Our study demonstrated the importance of including indigenous LEK in conservation planning for threatened species and habitats and the importance of traditional family values responsible for transferring oral knowledge.