Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

Dramatic changes in land use have occurred in arid and semi-arid lands of Asia duringthe 20th century. Grassland conversion into croplands and ecosystem degradation is widespreaddue to the high growth rate of human population and political reforms of pastoral systems. Rangeland degradation made many parts of this region vulnerable to environmental and political changes. The collapse of the livestock sector in some states of central Asia, expansion of livestockin China and intensive degradation of grasslands in China are examples of the responses of pastoral systems to these changes over the past decades. Carbon dynamics in this region is highly variable in space and time. Land use/cover changes with widespread reduction of forest and grasslands increased carbon emission from the region.     

Implications of behavioral change for the resilience of pastoral systems—Lessons from an agent-based model

In many dryland regions, traditional pastoral land use strategies are exposed to various drivers such as demographic or socio-economic change. This may lead to an adjustment of livelihood strategies and behavior of pastoral households, involving a change in attitudes toward livestock, pasture condition and social norms. We use an agent-based model to examine long-term social-ecological consequences and implications for system resilience of such behavioral changes (e.g., giving up a social norm). The model captures feedback between pastures, livestock and household livelihood in a common property grazing system. We systematically compare three stylized household behavioral types (traditional, maximizer and satisficer) that differ in their preferences for livestock, their compliance with social norms on pasture resting and how they are influenced by the behavior of others. Simulation results show that the traditional, norm-abiding household type maintains the pasture condition, provided that overall household numbers do not exceed a critical threshold. In contrast, a switch to a maximizer type that ignores norms may lead to long-term pasture degradation and livestock loss, pushing the system to an undesirable state. A change toward a new satisficing household type that constrains its herd size while diversifying its income sources can lead to improved pasture conditions and higher total livestock numbers, even with increased household numbers. We conclude that changes in household behavior have strong implications for long-term social-ecological system dynamics and have to be considered to assess the resilience of pastoral common property systems.     

Epiphytic lichens as indicators of grazing pressure in the Mongolian forest-steppe

The ecological impact of the traditional land use by pastoral nomads on forest ecosystems is little studied. We analyzed the influence of livestock density on epiphytic lichen diversity in larch forests of the Mongolian forest-steppe, which we selected as a case example because pastoral nomadism is here most widespread within Central Asia. Canonical correspondence analysis showed that the epiphytic lichen vegetation was strongly influenced by the livestock density within a radius of 1 km around the sampled forests. Goats together with horses were most significant at shaping lichen vegetation in the forest edges as were horses alone in the forest interiors. This result matches with the results of interviews with 169 herder families and own field observations, which substantiate that goats preferably graze at the edges, whereas horses often browse the interiors. The livestock impact is thought to be primarily exerted through fertilization by the animals and mechanical abrasion. Based on an indicator species analyses, we propose to use epiphytic lichens as indicators of the grazing impact at different livestock densities in the Mongolian forest-steppe. The proposed indication system can be used as a tool for the rapid assessment of the livestock grazing impact. It has the advantage that it is thought to average the livestock impact of several years, which is important with regard to the nomadic style of livestock husbandry. The use of lichens as indicator species can at least partly substitute the time-consuming interviewing of the herder families to assess livestock densities and their impact on forest biodiversity. The proposed indicator system could thus be used as a planning tool for purposes of nature conservation.     

Efficacy of Integrating Herder Knowledge and Ecological Methods for Monitoring Rangeland Degradation in Northern Kenya

The world-wide debate on land degradation in arid lands, usually linked to local land use practices, does not reflect methodological advancements in terms of assessments and monitoring that integrate local communities’ knowledge with ecological methods. In this paper, we evaluated the efficacy of three different methods related to herder assessments and monitoring of land degradation; herder knowledge and ecological methods of assessing impacts of livestock grazing along gradients of land use from settlement and joint monitoring of selected marked transects to understand long-term vegetation changes in southwestern Marsabit northern Kenya. The performance of each method was carefully evaluated and interpreted in terms of the indicators used by herders and ecologists. Herder interpretations were then related to ecologists’ empirical analysis of land degradation. The Rendille nomads have a complex understanding of land degradation which combines environmental and livestock productivity indicators, compared to conventional scientific approaches that use plant-based indicators alone. According to the herders, the grazing preference of various livestock species (e.g., grazers versus browsers) influences perceptions of land degradation, suggesting degradation is a relative term. The herders distinguished short-term changes in vegetation cover from long-term changes associated with over-exploitation. They attributed current environmental degradation around pastoral camps, which shift land use between the alternating wet and dry seasons, to year-round grazing. We deduced from long-term observation that herders interpret vegetation changes in terms of rainfall variability, utilitarian values and intensification of land use. Long-term empirical data (23 years) from repeated sampling corroborated herder interpretations. Land degradation was mostly expressed in terms of declines in woody plant species, while spatial and temporal dynamics of herbaceous species reflected the effects of seasonality. The efficacy of the three methods were inferred using explanatory strengths of ecological theory; insightfulness of the methods for describing land degradation and the likelihood of using the methods for promoting local community participation in the implementation of the UN Convention on Combating Desertification (CCD) and the Convention on Biological Diversity (CBD).     

Staging Social Structures: Ritual and Social Organisation in an Egalitarian Society. The Pastoral Pokot of Northern Kenya

The pastoral Pokot of northern Kenya represent their society as highly structured by descent and age grading. Descent groups (clans, lineages) and age grades (age sets, generation sets) are depicted as bounded but related units within a complex hierarchical and coherent system, the essence of Pokot society which is staged and visualised in major rituals. This study shows that they are not important in Pokot economic exchange. The formal analysis of livestock exchange networks centred upon individuals shows that emic representations do not match actual exchange behaviour. Complementing the well-established structuralist representation of pastoral social systems, this paper investigates the agency aspect, which has been largely unexplored. It furthermore documents how social exchange is contained in the various institutions of descent and age grading. Contextualising the case historically it is shown that the pastoral Pokot developed from a fragmented clan-based agro-pastoral society in which descent was the main ordering principle for land tenure and conflict management into a more comprehensive social entity with clearly definable borders to the outside, dense internal exchange networks and strong representations of the corporateness of subgroups. The rapid adoption of mobile livestock husbandry was accompanied by the rise of widespread exchange networks and social interaction with a much wider group of unrelated actors marking the foundations of a pastoral society.     

Biophysical Variability and Pastoral Rights to Resources: West African Transhumance Revisited

This paper focuses on a conundrum that has dominated the literature on pastoral mobility and institutions in dryland regions of the world, where livestock production is the main livelihood system. High spatiotemporal variability of rainfall and forage resources are seen to require flexible rules and porous social boundaries to facilitate pastoral mobility—characteristics that run counter to conventional views of the requirements for effective common property institutions. We seek to explore this paradox by investigating the spatiotemporal variability of forage availability (using satellite derived vegetation indices as a proxy for green forage) in four transhumance zones (“transhumance sheds”) in Mali, West Africa. For each transhumance shed, three characteristics with important institutional implications are evaluated over an eleven-year period between 2000 and 2010: the inter-annual variability of forage phenology, seasonal changes in connectivity of green forage patches, and the degree to which key forage locations exist in the form of consistently early green-up and/or late senescence. Periods of vegetation green-up and senescence, which determine the timing of transhumant livestock movements, are found to be sufficiently regular from year to year to be governed by conventional institutions. Seasonal changes in the north-south connectivity of green patches are sufficiently rapid for customary systems of sharing of pasture information to be effective (rather than more technologically sophisticated systems of pasture information). Moreover, transhumance sheds contain key pastoral forage sites, which because of their consistently early greening or late senescence, are strong candidates for territorial protection from alternative land uses such as agriculture. These findings support local herders’ views of transhumance as composed of regular patterns of herd movements along prescribed corridors between key pastoral sites. The seasonal regularity of key pastoral resources has been obscured by an overemphasis on environmental unpredictability that characterizes dryland systems at certain spatial and temporal scales. This paper suggests that policies directed at improving pastoral resource governance must focus instead on securing pastoralists’ access rights to movement corridors, specific pastures and water points.     

The challenge of participatory natural resource management with mobile herders at the scale of a Sub-Saharan African protected area

In Sub-Saharan Africa, the management of rangelands used by mobile populations, such as transhumant herders, must include large scale, sometimes cross-border, components. This mobility, common and significant in transhumant livestock production systems is, in most cases, not taken into account in conservation and natural resources management strategies around protected areas. Most conservation projects which include a development goal are designed to provide support to sedentary subsistence agricultural populations. Securing “pastoral lands” is seldom included as part of protected areas land management approaches. This paper focuses on the difficulty of integrating pastoral, agricultural and conservation issues into a regional land management plan. Based on a case study in Chad (Zakouma National Park), we pay particular attention to local mechanisms of land tenure negotiation, the mobile actors and the complex political landscape that this creates.     

Edge and land-use effects on epiphytic lichen diversity in the forest-steppe ecotone of the Mongolian Altai

Epiphytic lichen diversity was studied in forests of Siberian larch (Larix sibirica) in the forest-steppe ecotone of the Mongolian Altai. These forests are utilized for livestock grazing, fuelwood collection and occasional logging by pastoral nomads. The density of nomad households in the proximity of the forests influences epiphytic lichen diversity more strongly than the position of sample trees in the forest interior or at the forest line to the steppe. This suggests that land use exerts a stronger effect on lichen diversity than the distinct gradient in microclimate between the forest interior and the forest edge. The co-occurrence of nitrophytes with anitrophytic acidophytes on a small spatial scale as well as higher N and Ca concentrations and pH values in the bark of larch trees at the forest edge than in the forest interior indicate that moderate livestock grazing increases the epiphytic lichen diversity due to an increase of the diversity of chemically different microhabitats. Preference of many lichen species (and of rare species in particular) for overmature and decaying trees suggests that logging and fuelwood collection has adverse effects on epiphytic lichen diversity. This adverse effect is likely to be more crucial for lichen diversity than the putatively positive effect of livestock grazing, since more lichens with a preference for old and decaying trees than for nitrogen-enriched bark were found. The present study is the first one investigating the impact of pastoral nomadism in Central Asia on epiphyte diversity.     

Livestock Settlement Dynamics in Drylands: Model application in the Monte desert (Mendoza,Argentina)

Human settlements in arid environments are becoming widespread due to population growth, and without planning, they may alter vegetation and ecosystem processes, compromising sustainability. We hypothesize that in an arid region of the central Monte desert (Mendoza, Argentina), surface and groundwater availability are the primary factors controlling livestock settlements establishment and success as productive units, which affect patterns of degradation in the landscape. To evaluate this hypothesis we simulated settlement dynamics using a Monte Carlo based model of Settlement Dynamics in Drylands (SeDD), which calculates probabilities on a gridded region based on six environmental factors: groundwater depth, vegetation type, proximity to rivers, paved road, old river beds, and existing settlements. A parameter sweep, including millions of simulations, was run to identify the most relevant factors controlling settlements. Results indicate that distances to rivers and the presence of old river beds are critical to explain the current distribution of settlements, while vegetation, paved roads, and water table depth were not as relevant to explain settlement distribution. Far from surface water sources, most settlements were established at random, suggesting that pressures to settle in unfavorable places control settlement dynamics in those isolated areas. The simulated vegetation, which considers degradation around livestock settlements, generally matched the spatial distribution of remotely sensed vegetation classes, although with a higher cover of extreme vegetation classes. The model could be a useful tool to evaluate effects of land use changes, such as water provision or changes on river flows, on settlement distribution and vegetation degradation in arid environments.