Cover-based allometric estimate of aboveground biomass of a non-native, invasive annual grass (Bromus tectorum L.) in the Great Basin, USA

Cheatgrass (Bromus tectorum L.) presence in the Great Basin is associated with an increase in fire frequency andsize, likely due to increased spatial continuity of fine fuel biomass. Measurements of the extent and cover ofcheatgrass are steadily improving, but the strength of the relationship between cover and aboveground biomass(AGB) is unclear. An allometric equation that can reliably convert cover to AGB of cheatgrass would allow forimproved incorporation of regional estimates of cover into models of fire activity, carbon storage, and net pri&shy;mary productivity, all of which rely on biomass. We measured cover and AGB of cheatgrass at 60 locations in thenorth-central Great Basin and used these measurements to model the relationship. We found a strong, linearrelationship between the percent cover and AGB, which was improved after square root transformation of bothcover and AGB, and after incorporating the number of days after peak NDVI that the biomass and cover weremeasured. These results show that AGB of cheatgrass can be reliably estimated from cover. It is likely thatallometric equations based on cover will be effective for other grass species, but care must be taken to account forphenology (e.g., peak NDVI) in the estimation.</p

Elevational movement ecology and vegetational associations of birds in the Great Basin

There is strong evidence that climate change has caused many species to shift their geographical distributions as suitable habitat changes both spatially and temporally. Determining mechanisms behind distributional shifts and understanding why some species are shifting while others are not, may offer clues about adaptive capacity and species persistence into the future. The research presented here examines shifts and variability in species’ distributions in a community of birds in the Great Basin, USA using a long-term data set on avian abundance and novel occupancy and abundance modeling techniques. Chapter one examined within breeding season elevational movement of 25 species of birds across two subregions of the Great Basin. This chapter examined the hypothesis that some species of birds disperse upslope as the breeding season progresses to track the distribution of higher-quality, late-season habitat as lower elevations become relatively hot and dry. Through the use of multinominal N-mixture models I examined 25 bird species over 7 years in two distinct regions of the Great Basin. I found evidence of upslope elevational dispersal in six species, and evidence of downslope elevational dispersal in one species, Green-tailed Towhee (Pipilo chlorurus). The results largely were consistent with the idea that environmental heterogeneity can drive dispersal. Changes in availability of six of the seven species (all except Broad-tailed Hummingbird [Selasphorus platycercus]) that dispersed within the season were associated significantly with shifts in primary productivity and food. The results of this chapter add to a growing body of research suggesting that within-breeding season dispersal is much more common than previously thought.Chapter two assessed shifts in the elevational distribution of birds from 2001-2020. Although montane species are generally predicted to respond to climate change via upslope elevational movement, many populations and species are not moving in synchrony with increasing temperatures. This chapter examined 32 species of birds for evidence of elevational shifts at the upper and lower 25% of their elevational distribution as well as across the full elevational distribution. The elevational distributions of 19 species shifted, and the four shifts along the full elevational gradient were downslope. About half (46%) of the distributional shifts at the lower or upper elevational edges were upslope. Chapter two found evidence that elevational shifts in bird distributions may be a response to climate change, a signal detected over a relatively short time series (9 and 19 years). Finally, chapter three examined associations of bird species with two different types of vegetational traits, plant physiognomy (characterized by functional groups) and plant floristics (characterized by plant species), in five biogeographically distinct subregions of the Great Basin. I hypothesized that plant physiognomy was significantly associated with bird occupancy across the Great Basin, while plant floristics were associated with occupancy within an individual subregion. This chapter found considerable variation among subregions with respect to which covariates were significantly associated with occupancy, and that the number and strength of bird-vegetation associations varied substantially between subregions. The results of this work suggest that for many bird species, vegetational associations are not transferrable across subregions, and that there is distinct geographical variation in vegetational preferences for some Great Basin bird populations

Fire, livestock grazing, topography, and precipitation affect occurrence and prevalence of cheatgrass (Bromus tectorum) in the central Great Basin, USA

Cheatgrass (Bromus tectorum) has increased the extent and frequency of fire and negatively affected native plant and animal species across the Intermountain West (USA). However, the strengths of association between cheatgrass occurrence or abundance and fire, livestock grazing, and precipitation are not well understood. We used 14 years of data from 417 sites across 10,000 km2 in the central Great Basin to assess the effects of the foregoing predictors on cheatgrass occurrence and prevalence (i.e., given occurrence, the proportion of measurements in which the species was detected). We implemented hierarchical Bayesian models and considered covariates for which  \u3e  0.90 or  \u3c  0.10 of the posterior predictive mass for the regression coefficient ≥  0 as strongly associated with the response variable. Similar to previous research, our models indicated that fire is a strong, positive predictor of cheatgrass occurrence and prevalence. Models fitted to all sample points and to only unburned points indicated that grazing and the proportion of years grazed were strong positive predictors of occurrence and prevalence. In contrast, in models restricted to burned points, prevalence was high, but decreased slightly as the proportion of years grazed increased (relative to other burned points). Prevalence of cheatgrass also decreased as the prevalence of perennial grasses increased. Cheatgrass occurrence decreased as elevation increased, but prevalence within the elevational range of cheatgrass increased as median winter precipitation, elevation, and solar exposure increased. Our novel time-series data and results indicate that grazing corresponds with increased cheatgrass occurrence and prevalence regardless of variation in climate, topography, or community composition, and provide no support for the notion that contemporary grazing regimes or grazing in conjunction with fire can suppress cheatgrass

Building Trust with Agricultural and Rural Decision-Makers through Engaged Climate Educational Models in the Rural U.S. Central Great Plains

Potential climate change impacts on Central Great Plains (CGP) agricultural production are profound and highly likely to affect both national and global food supplies and related social and economic systems. Predicted climate changes include increasing temperatures with more variability including, greater precipitation events, longer and more frequent heat waves. These changes will impact agricultural production, water supply, and human health. Three annual crops, corn, sorghum, and wheat, which collectively account for 81 million hectares of agricultural land in the U.S., are concentrated in the Midwest and Central Great Plains. These crops are the mainstay for U.S. agriculture and account for $30.1 billion of agricultural production annually. The CGP also has been identified as one of the few regions around the globe that has a high degree of coupling of climate to soil moisture conditions, suggesting that any changes in precipitation will amplify climate feedbacks. This increases the level of uncertainty regarding the effects of climate change on production agriculture. Despite the fact that both Nebraska and Kansas are heavily dependent upon agriculture for their economic well-being, rural citizens’ responses to climate change remain mixed. Regional research has found that most rural Nebraskans felt at least fairly well informed about climate change (71%), believed climate change was happening (58%), and were concerned or very concerned about climate change impacting the U.S. (60%), but other research indicates that sizable numbers of producers say that weather and climate forecasts do not influence their agricultural decisions (e.g., ranging from 9% to 42% depending on the specific forecast product and agricultural decision). Focus groups from our Phase I partnership conducted with three sets of stakeholders (agricultural producers, rural community members, and agriculture/science educators representing future agricultural producers/rural community members) suggest these stakeholder group members were eager to learn more about climate and how it might change, but that their purposes, goals and attitudes toward the information vary widely. Different stakeholder groups want access to different types of information as well as how to use that information for different purposes. Moreover, they want increased access to data such that it allows them to decide for themselves how the data could be useful to them. Despite these differences, all the focus group stakeholders desire information that they can trust, is frequently and quickly updated, and easy to access. Most of all, they want locally relevant information. Conclusions from Phase I emphasize locally relevant, inquiry-based approaches with multiple points of access to the development and delivery of educational programs on climate change. We have developed a larger research and implementation framework outlining these multiple points of entry for different stakeholder audiences and a plan for programming across the three stakeholder groups based on this framework. Information about project personnel, partners, and other project information can be found at the project website: www.ksu.edu/cgp-cce