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Rangelands encompass 30–40% of Earth's land surface and support 1 to 2 billion people. Their predominant use is extensive livestock production by pastoralists and ranchers. But rangelands are characterized by ecological, economic, and political marginality, and higher value, more intensive land uses are impinging on rangelands around the world. Earth Stewardship of rangelands must address both livestock management and the broader socioecological dynamics that promote land‐use changes, fragmentation, and degradation. We identify specific gradients on which human–rangeland systems can be arrayed, including issues of variability, adaptation to disturbance, commercialization, land‐use change, land‐tenure security, and effective governance, and we illustrate the gradients' interactions and effects in sites worldwide. The result is a synthetic framework to help in understanding how rangeland Earth Stewardship can be achieved in the face of marginality, globalization, and climate change.

A significant change in the geography of livestock raising over the past 30 years is the southerly movement of FulBe herds into the humid Sudanian and Guinean savannas of West Africa. The literature suggests that the severe droughts of the early 1970s and mid-1980s were the driving force behind this southern expansion of mobile livestock raising. The conventional view is that drought forced herders to seek greener pastures to the south, an area that zebu cattle have previously avoided because of the presence of tsetse flies, the vector of animal sleeping sickness (trypanosomiasis). This "sudden push" hypothesis places Sahelian herds in savanna pastures in a matter of a 1-3 years. This stimulus-response model runs counter to our observations and understanding of the social and ecological processes influencing FulBe herd movements. We challenge the "sudden shift" thesis at the regional scale by arguing that the southerly expansion of FulBe herds has proceeded according to a more complex temporal frame that includes generational, biological, and social historical timeframes and periodicities. We distinguish between short-term shifts ("test movements") and more permanent shifts ("migration movements"). These mobility patterns are linked to contingent factors such as cattle diseases, drought, and political instability, as well as to more structural and adaptive features such as the establishment of social networks, herding contracts, and cattle cross-breeding. Shifts in livestock ownership and the social differentiation among herders are important variables for understanding changes in herd movements. We conclude that the permanent shift of herds to the humid savannas of West Africa has been preceded by a series of social and agroecological adjustments that operate on decadal and generational time scales.

In even—aged monocultures, distributions of seedling mass shift from symmetric to right—skewed as plants grow. One explanation for the shift is that numerous small individuals and few large ones reveal underlying dominance and suppression caused by depletion of resources. A second explanation is that the asymmetry represents a shift from normal to lognormal mass distributions because of variance in exponential growth rate. As a consequence of the first mechanism but not the second, the presence of resource depletion should increase both the skewness and the variance of distributions of individual plant mass. Even—aged populations of the prairie grass Festuca paradoxa were grown in the greenhouse for 44 d with and without competition (dense flats or one individual to a container), and with and without augmented nutrients. At each harvest, plants grown densely were smaller than isolated plants, demonstrating that resource depletion occurred. Distributions of mass of isolated plants skewed first and remained more highly skewed throughout the experiment. At a given mean mass, the standard deviation of mass for crowded and isolated plants did not differ. At a given mean mass, the skewness of mass for crowded plants was not greater than for isolated ones. The second explanation is supported, and shifts in distribution shape can be attributed to growth alone, in the absence of dominance and suppression. Competition in this case did not promote skewing but actually retarded its appearances. Consistency of these results with previous findings is discussed.

To understand the broader epistemological and ontological politics of human dimensions of climate change, this review adopts a political ecology approach, informed by Science and Technology Studies concepts and research on multiple ontologies. We are particularly interested in assessing critical approaches to climate change knowledge as related to adaptation policies. The review addresses three specific areas where more critical engagement could help move debates about knowledge politics in human dimensions research forward in fruitful ways: first, discourse and a focus on the language used to talk about and reflect on human dimensions of climate change; second, co-production and the troubling proliferation of depoliticized "instrumental" co-productions of knowledge for adaptation; and third, the emerging literature on multiple ontologies exposing multiple enactments of climate change processes. We review each of these areas of literature, highlighting where more direct engagement with epistemological, ontological, and ethical questions is underway. In doing so, we subject the knowledge and practices that underlie dominant understandings of climate change to critical political ecology scrutiny.