Assessing historical and future habitat models for four conservation‐priority Mojave Desert species

Abstract

Aim: Modelling and quantifying habitat changes using three historical field surveys for four Mojave Desert species and projecting future scenarios. Location: Newberry Mountains, southern Nevada, USA. Methods: Three vegetation field surveys were conducted, ending in 1979, 2008 and 2016, respectively. Field data collection across three time steps resulted in a unique dataset with 100 re-surveyed 0.06-ha plots. Using Maxent ecological niche modelling and 800-m resolution Parameter Elevation Regressions on Independent SlopesModel (PRISM) temperature and precipitation data, habitat was assessed for four high-elevation species. Recognizing that missing location data is a common challenge in species distribution modelling, sensitivity analysis was conducted utilizing three high-elevation plots that species inhabited during the first two field surveys but that were unable to be sampled in 2016. Area under the curve for three species' model runs exceeded 0.95, while one wider-distributed species exceeded 0.79 for all runs. Future scenarios were also modelled under temperature increases and 16% and 0% reductions in precipitation. Results:The number of presence locations and densities for Juniperus californica, Pinus monophylla, Quercus turbinella and Yucca schidigera decreased from 1979 to 2016, while their average elevational distribution increased. Using the 100 plots measured each of the three study years, models for all four species indicated decreases in potential suitable habitat ranging from 10% to 45%. When including the three highest elevation plots not re-sampled in 2016, but likely still containing the modelled species, modelled habitat loss ranged from 0% to 29%. Future model projections show drastic reductions in the suitable habitat of all four modelled species.Main conclusions: While many Maxent ecological modelling studies have been conducted, few have incorporated repeat surveys of identical plots as in our study. Model projections using a unique 100-plot dataset suggest that suitable habitat area is contracting for the species studied, and this correlated with climatic warming and drying in the Mojave Desert. Despite model projections that show nearly complete loss of suitable habitat in 2053, care should be taken given uncertain estimates of the velocity of climate change and the slower pace of habitat contractions measured in the field.

The differential contribution of coyotes and passerines on future biotic carbon storage through juniper seed dispersal

“…Juniper saw minimal losses of their existing range along the trailing edge of their distribution. These results bolster findings that juniper species are projected to be resilient to changing climate conditions (Volder et al 2013), and will exploit higher elevations in response to warming (Guida et al 2019). Future increases in temperatures at higher elevations allowed for maximum dispersal of juniper upslope and into high plains by coyotes in early timesteps, which in turn tapered off through time as climate change reduced suitable niches (Fig.…”

‘Unscrambling’ the drivers of egg production in Agassiz’s desert tortoise: climate and individual attributes predict reproductive output

“…Precipitation will likely be influenced as well. In the last century, some areas of the Mojave Desert have already seen a 20% reduction in precipitation (Guida et al 2019); however, some future climate projections disagree about whether precipitation will increase or decrease for this region (Bachelet et al 2016). Indeed, increasing aridity may already be affecting desert tortoises; over the modeled timeframe (1990−2018) our models predict a gradual but significant decline in range-wide egg production potential.…”

Species distribution modelling supports the study of past, present and future biogeographies

“…It has been shown that correlative SDM, if corrected for dispersal limitations and land use change, reconstructed the broad outlines of changing species distributions of British birds for the last 40 years as well as or better than process‐explicit demographic models—SDMs reconstructed the magnitude of range size change, although not grid cell level range change (Fordham et al, 2018). Another study based on repeated surveys of desert plant communities over the past four decades showed that SDMs calibrated for different time periods indicate declines in suitable habitat corresponding to observed declines and shifts, while projections under future climate change scenarios suggest drastic reductions in habitat for those plants (Guida et al, 2019). A recent example uses SDM to predict current and future habitat under climate change, paired with demographic data from a long‐running reciprocal transplant experiment for a rare herb in Europe (Sanczuk et al, 2022).…”