SHRUBLANDS OR GRASSLANDS TO NOVEL ECOSYSTEMS Deb Peters, Jin Yao

Temporal context (legacies, lags, feedbacks, past & recent management practices, climate, disturbance) Past Present Perennial grassland Woody plant invaded grassland Coppice duneland Environmental drivers (climate, grazing) Urban, suburban, agricultural Future states plant plant assemblage landscape unit Soil-geomorphic template Transport vectors Resource redistribution Spatial context Ag land Shrubland Novel systems (exotic grasses) Perennial grassland Jornada LTER framework (alternative states, multiple scales, spatial and temporal context)

Lehmann lovegrass occurrence at Jornada McGlone CM Response of an introduced grass, Eragrostis Lehmanniana, to a prescribed burn in the Northern Chihuahuan Desert: Implications for community dynamics. NMSU Master Thesis. ERLE patches and presence GPSed during by McGlone CM. G SUMM C CALI C SAND in the 1950s and 1960s, JER staff seeded Lehmann lovegrass for restoration or spring forage with limited success. Current populations are probably from seeds transported downslope from seeded populations.

Lehmann lovegrass increased on long-term NPP plots in wet period ( ; die off with freeze in 2011) McGlone CM Response of an introduced grass, Eragrostis Lehmanniana, to a prescribed burn in the Northern Chihuahuan Desert: Implications for community dynamics. NMSU Master Thesis. % of quadrat with ERLE G SUMM C CALI C SAND Frequency data from NPP locations

Regionally, Lehmann lovegrass has expanded throughout the Southwest (county-level reporting) Data source: USDA plants database Frequency (%) Santa Rita, AZ Lehmann lovegrass expansion (exploded) in Sonoran Desert in 1990s; maintained thru time Frequency (%) Basal cover (%) Invasive grass from South Africa

Objectives I. To quantify the climatic and edaphic controls on Lehmann lovegrass seedling establishment and survival for: 1. the Jornada landscape 2. the Chihuahuan Desert II. To predict its future geographic distribution under alternative climate scenarios. Collaboration with EF – ( ) Lehmann lovegrass invasion as a novel ecosystem in the Chihuahuan Desert

SOILWAT  Daily time step, multi-layer model of soil water dynamics and seedling establishment  Parameterized using literature values for Lehmann lovegrass and similar native grass species Model validation  Field observations vs. simulated results  Jornada (Chihuahuan Desert) vs. Santa Rita (Sonoran Desert) SOILWAT model parameterization and validation

1.Establishment simulated for 57 weather stations representing Chihuahuan Desert 2.Current daily precipitation and temperature 3.Alternative climate scenarios Temperature increase by 2.5 o C Vary precipitation amount (no change, decrease or increase by 10%) 4. 6 soil types 5. Extrapolate to entire region using regression equations and PRISM climate data Chihuahuan Desert simulated seedling establishment

Regression equations for extrapolation - Loamy sand and sandy loam (examples) SoilY_intMAPPPT _Jul PPT _Sep Tmean _Dec Tmin _Jan R2R2 Current climate Loamy sand Sandy loam T increases by 2.5 o C, PPT stays same Loamy sand Sandy loam T increases by 2.5 o C, PPT decreases by 10% Loamy sand Sandy loam T increases by 2.5 o C, PPT increases by 10% Loamy sand Sandy loam N = 57, model p < for all cases.

PRISM data for current climate Mean annual precipitationMean annual temperature

Current climate Hotter, PPT no change Regional variation in change in seedling establishment on loamy sand soils (mesquite) Hotter and wetterHotter and drier

Current climate Sandy loam soils greater change in establishment than loamy sand soils sandy loam (grassland) loamy sand (mesquite) Hotter and drier Current climate Hotter and drier

Objectives - future I. To quantify the climatic and edaphic controls on Lehmann lovegrass seedling establishment and survival for: 1. the Jornada landscape – future plans are to simulate the Jornada under climate change scenarios 2. the Chihuahuan Desert II. To predict its future geographic distribution under alternative climate scenarios. III. Continue long-term monitoring of Lehmann’s populations IV. Model results lead to mechanistic field studies Lehmann lovegrass invasion as a novel ecosystem in the Chihuahuan Desert