Simulated distribution of Eragrostis lehmanniana (Lehmann lovegrass): Soil–climate interactions complicate predictions

Abstract

The invasive perennial grass Eragrostis lehmanniana has expanded rapidly throughout the Sonoran Desert (SD) while remaining sparse and patchily distributed in the neighboring Chihuahuan Desert (CD). As temperatures and patterns in precipitation change, identifying the drivers limiting spread in the CD is needed. Our objectives were (1) to identify the climatic and edaphic factors limiting recruitment of E. lehmanniana throughout the CD and (2) to predict the edaphic and climatic locations in the CD where this species is expected to have higher probabilities of recruitment under future climatic conditions. Recruitment was simulated at 57 locations throughout the CD with a daily, multilayer soil water model (SOILWAT) that was parameterized and tested to develop recruitment parameters for E. lehmanniana using long-term data from research stations in the SD and CD. Logistic regression was used to predict recruitment across the CD using climate and soil factors to create a map of simulated recruitment under current and alternative climate scenarios. Simulated recruitment under current climate was low for most of the CD. However, localized areas with high probabilities (>0.8) occurred along the western transition between the CD and the SD, and in the southern extent of the CD. In general, the CD climate is too cool and dry for rapid and widespread invasion. However, increases to temperature and precipitation are likely to increase recruitment success. Interactions among soil, temperature, and precipitation were important to increases in recruitment of E. lehmanniana and are expected to lead to heterogeneous increases in abundance as climate continues to change. This patchy increase in abundance will result in changes in its geographic distribution that will make predictions in the future challenging.

Effect of spatial and temporal “drought legacy” on dust sources in adjacent ecoregions

“…Müller and Bahn (2022) recommended that future studies of drought legacy should look beyond ecosystem‐focused effects to consider interactions of drought legacies with other global change factors including weather and climate extremes, and that accounting for the implications of drought legacies on subsequent droughts is essential for understanding long‐term consequences of a changing climate for ecosystems. Our finding that drought legacy (drought memory) has impacts on aeolian dust sources in North America should be tested for other terrestrial dust source regions, especially those with different land use/land cover types, since different vegetation communities and species have different responses to environmental legacies (Cranko Page et al, 2023) including drought (Luo et al, 2023) and wind erosion (Burruss et al, 2023). We also recommend future investigations of the extended spatiotemporal effects of drought legacy on other aspects of earth‐surface dynamics, including land cover change and wildfire, in a variety of ecoregions.…”

“…In the Southern Great Plains, dust events regularly developed not only during intense drought, but also during low drought conditions. This could be due to the strong sensitivity to drought by aeolian processes in the region as off‐season fallow and the abandonment of drought‐stricken agricultural fields leaves them susceptible to wind erosion (Burruss et al, 2023; Ray et al, 2018). It could also represent the influence of land use on dust initiation being more dominant than the role of drought in this highly agricultural region.…”

Abrupt transitions in a southwest USA desert grassland related to the Pacific Decadal Oscillation

“…However, similar to the mid-century drought, novel plant communities may emerge in recovery, potentially ECOLOGY dominated by non-native species (Diez et al, 2012). It is possible that the next cycle of recovery, especially as the climate warms, will feature a non-native perennial grass, Eragrostis lehmanniana, that is widespread throughout the Southwest (Burruss et al, 2022). Alternatively, future recovery of grasslands may be prevented by competition with woody plants, advanced soil erosion, and warmer temperatures (Schreiner-McGraw et al, 2020).…”

Managing an arid ranch in the 21st century: New technologies for novel ecosystems

“…An invasive perennial grass, Lehmann lovegrass ( Eragrostis lehmanniana ) is also expanding from formerly isolated populations. 23 Wind and water erosion from bare ground areas is a primary resource concern. Our cow-calf research herd was reduced considerably during recent drought years.…”