Sustaining Working Rangelands: Insights from Rancher Decision Making

Grazed rangeland ecosystems encompass diverse global land resources and are complex social-ecological systems from which society demands both goods (e.g., livestock and forage production) and services (e.g., abundant and high-quality water). Including the ranching community's perceptions, knowledge, and decision-making is essential to advancing the ongoing dialogue to define sustainable working rangelands. We surveyed 507 (33% response rate) California ranchers to gain insight into key factors shaping their decision-making, perspectives on effective management practices and ranching information sources, as well as their concerns. First, we found that variation in ranch structure, management goals, and decision making across California's ranching operations aligns with the call from sustainability science to maintain flexibility at multiple scales to support the suite of economic and ecological services they can provide. The diversity in ranching operations highlights why single-policy and management "panaceas" often fail. Second, the information resources ranchers rely on suggest that sustaining working rangelands will require collaborative, trust-based partnerships focused on achieving both economic and ecological goals. Third, ranchers perceive environmental regulations and government policies-rather than environmental drivers-as the major threats to the future of their operations

Plant growth enhancement by elevated CO2 eliminated by joint water and nitrogen limitation

http://www.nature.com/ngeo/Rising atmospheric CO2 concentrations can fertilize plant growth. The resulting increased plant uptake of CO2 could, in turn, slow increases in atmospheric CO2 levels and associated climate warming. CO2 fertilization e ects may be enhanced when water availability is low, because elevated CO2 also leads to improved plant water-use e ciency. However, CO2 fertilization e ects may be weaker when plant growth is limited by nutrient availability. How variation in soil nutrients and water may act together to influence CO2 fertilization is unresolved. Here we report plant biomass levels from a five-year, open-air experiment in a perennial grassland under two contrasting levels of atmospheric CO2, soil nitrogen and summer rainfall, respectively. We find that the presence of a CO2 fertilization e ect depends on the amount of available nitrogen and water. Specifically, elevated CO2 levels led to an increase in plant biomass of more than 33% when summer rainfall, nitrogen supply, or both were at the higher levels (ambient for rainfall and elevated for soil nitrogen). But elevated CO2 concentrations did not increase plant biomass when both rainfall and nitrogen were at their lower level. We conclude that given widespread, simultaneous limitation by water and nutrients, large stimulation of biomass by rising atmospheric CO2 concentrations may not be ubiquitous

Remote detection of invasive alien species

The spread of invasive alien species (IAS) is recognized as the most severe threat to biodiversity outside of climate change and anthropogenic habitat destruction. IAS negatively impact ecosystems, local economies, and residents. They are especially problematic because once established, they give rise to positive feedbacks, increasing the likelihood of further invasions and spread. The integration of remote sensing (RS) to the study of invasion, in addition to contributing to our understanding of invasion processes and impacts to biodiversity, has enabled managers to monitor invasions and predict the spread of IAS, thus supporting biodiversity conservation and management action. This chapter focuses on RS capabilities to detect and monitor invasive plant species across terrestrial, riparian, aquatic, and human-modified ecosystems. All of these environments have unique species assemblages and their own optimal methodology for effective detection and mapping, which we discuss in detail

Increasing flexibility in rangeland management during drought

Extreme droughts like the recent 2011-2013 drought impacting the central and western United States present a challenge to sustaining livestock ranching operations and the ecosystem goods and services they produce. Wyoming ranchers manage half of this drought-prone state and are at the forefront of this challenge. We examined Wyoming ranchers' drought management strategies and how ranch characteristics affect drought management flexibility, a key component of resilience, through a mail survey. We find that many survey respondents manage drought in similar ways, by selling livestock and buying feed, highlighting the market risks associated with drought. Ranches that are larger, include yearling livestock, use shorter grazing periods, and/or incorporate alternative on-ranch activities (e.g., hunting) use more drought management practices and thus have greater flexibility. Larger ranches experience fewer drought impacts, highlighting advantages of a larger resource base. Our findings suggest three components of national drought policy that encourages flexibility and thus increases resilience of ranches to drought: (1) encouraging forage-sharing mechanisms; (2) promoting income diversification that is independent of climatic variability; and (3) facilitating a shift to diversified livestock production systems. These measures could increase sustainability of ranching livelihoods and provision of ecosystem services despite predicted increases in intensity and duration of future droughts. © 2014 Kachergis et al

Increasing flexibility in rangeland management during drought

Extreme droughts like the recent 2011-2013 drought impacting the central and western United States present a challenge to sustaining livestock ranching operations and the ecosystem goods and services they produce. Wyoming ranchers manage half of this drought-prone state and are at the forefront of this challenge. We examined Wyoming ranchers' drought management strategies and how ranch characteristics affect drought management flexibility, a key component of resilience, through a mail survey. We find that many survey respondents manage drought in similar ways, by selling livestock and buying feed, highlighting the market risks associated with drought. Ranches that are larger, include yearling livestock, use shorter grazing periods, and/or incorporate alternative on-ranch activities (e.g., hunting) use more drought management practices and thus have greater flexibility. Larger ranches experience fewer drought impacts, highlighting advantages of a larger resource base. Our findings suggest three components of national drought policy that encourages flexibility and thus increases resilience of ranches to drought: (1) encouraging forage-sharing mechanisms; (2) promoting income diversification that is independent of climatic variability; and (3) facilitating a shift to diversified livestock production systems. These measures could increase sustainability of ranching livelihoods and provision of ecosystem services despite predicted increases in intensity and duration of future droughts. © 2014 Kachergis et al

Evaluation of APEX modifications to simulate forage production for grazing management decision-support in the Western US Great Plains

Context: Understanding how grazing management decisions influence the productivity and composition of rangeland plant communities is essential for the development of effective strategies to sustainably produce multiple ecosystem goods and services. Informed with experimental measurements, simulation models can advance our understanding and stewardship of rangeland ecosystems. Objective: Our main objective was to evaluate the APEX (Agricultural Policy/Environmental eXtender) plant growth modules and grazing animal selectivity in simulating forage production using experimental data collected from both traditional season-long grazing and adaptive rotational grazing management on western rangelands. Specifically, we evaluated APEX's capability to simulate forage productivity and its response to soil types and climate conditions under grazing management options. Methods: Capitalizing on a comparative field study with 20 large pastures (> 123 ha each), APEX modifications were evaluated by comparing simulated forage production with experimental data. The field study evaluated traditional grazing (season long grazing on a single pasture) and an alternative grazing system that utilized collaborative adaptive rangeland management with stakeholders engaged in decision making (such as when and where to rotate a single herd). APEX was modified to include rotational grazing based on a user-defined sequence and automatic rotational grazing based on user-defined forage grazing limits and minimum/maximum grazing durations. Results and conclusions: The APEX model was able to simulate the relative differences in forage production between grazing treatments, across years, and among soil types; however, APEX underestimated forage production in 2015 and 2017 due to overestimating drought stress for the warm season perennial grass functional group. Simulation of grazing management scenarios showed that the collaborative adaptive management decision criteria resulted in grazing durations that produced more forage than consistent 7- or 14-day rotation intervals. Significance: These modifications were needed to capture the complexity of semiarid environments and thus enhance APEX to better assess grazing management decisions on forage production in regions such as the Western US Great Plains

Regional contingencies in the relationship between aboveground biomass and litter in the world’s grasslands

Based on regional-scale studies, aboveground production and litter decomposition are thought to positively covary, because they are driven by shared biotic and climatic factors. Until now we have been unable to test whether production and decomposition are generally coupled across climatically dissimilar regions, because we lacked replicated data collected within a single vegetation type across multiple regions, obfuscating the drivers and generality of the association between production and decomposition. Furthermore, our understanding of the relationships between production and decomposition rests heavily on separate meta-analyses of each response, because no studies have simultaneously measured production and the accumulation or decomposition of litter using consistent methods at globally relevant scales. Here, we use a multi-country grassland dataset collected using a standardized protocol to show that live plant biomass (an estimate of aboveground net primary production) and litter disappearance (represented by mass loss of aboveground litter) do not strongly covary. Live biomass and litter disappearance varied at different spatial scales. There was substantial variation in live biomass among continents, sites and plots whereas among continent differences accounted for most of the variation in litter disappearance rates. Although there were strong associations among aboveground biomass, litter disappearance and climatic factors in some regions (e.g. U.S. Great Plains), these relationships were inconsistent within and among the regions represented by this study. These results highlight the importance of replication among regions and continents when characterizing the correlations between ecosystem processes and interpreting their global-scale implications for carbon flux. We must exercise caution in parameterizing litter decomposition and aboveground production in future regional and global carbon models as their relationship is complex

Long-term impacts of season of grazing on soil carbon sequestration and selected soil properties in the arid Eastern Cape, South Africa

BACKGROUND AND AIMS : The karoo biomes of South Africa are major feed resources, yet soil nutrient depletion and degradation is a major problem. The objective of this study was to assess impacts of long-term (>75 years) grazing during spring (SPG), summer (SUG), winter (WG) and exclosure (non-grazed control) treatments on soil nutrients, penetration resistance and infiltration tests. METHODS : A soil sampling campaign was carried out to collect soil to a depth of 60 cm to analyse bulk density, soil physical and chemical parameters as well as soil compaction and infiltration. RESULTS : Generally, grazing treatments reduced soil organic C (SOC) stocks and C:N ratios, and modified soil properties. There was higher SOC stock (0.128 Mg ha-1 yr-1) in the exclosure than in the SPG (0.096 Mg ha-1 yr- 1), SUG (0.099 Mg ha-1 yr-1) and WG (0.105 Mg ha-1 yr-1). The C:N ratios exhibited similar pattern to that of C. From the grazing treatments, the WG demonstrated 7 to 10% additional SOC stock over the SPG and SUG, respectively. CONCLUSIONS : Short period animal exclusion could be an option to be considered to improve plant nutrients in sandy soils of South Africa. However, this may require a policy environment which supports stock exclusion from such areas vulnerable to land degradation, nutrient and C losses by grazing-induced vegetation and landscape changes.Department of Science and Technology University of Pretoria) and the European Communities, 7th framework program under the grant agreement No. 266018, ANIMALCHANGE project.http://link.springer.com/journal/111042016-12-31hb201