Managing California rangelands: implications of weather patterns on plant composition

Transcription

1 Managing California rangelands: implications of weather patterns on plant composition Joan Dudney, Loralee Larios, Lauren Hallett, Erica Spotswood and Katharine Suding University of California, Berkeley

2 Overview Background Study description Results Broader applications

3 Rangelands & climate change Source:

4 What We Know Precipitation = grass year Temperature and timing matter Photo: Nomadic Lass

5 Questions 1. Functional groups: how do functional groups respond to annual weather and seasonal weather? 2. Lagged effects: how does previous year s weather affect current year abundance?

6 Exotic Grasses Previous year: High Rainfall Exotic Forbs

7 Exotic Grasses Previous year Exotic Forbs

8 Exotic Grasses Previous year Current year Exotic Forbs

9 Methods Vasco Caves Pleasant Ridge Sunol Regional

10 Five Functional Groups 1. Native Annual Forbs (NAF) 2. Native Perennial Grasses (NPG) 3. Native Perennial Forbs (NPF) Photo: Teddy Llovet Photo: Olive O. 4. Exotic Annual Grasses (EAG) 5. Exotic Annual Forbs (EAF) Photo: Manuel M.V. Photo: Pancrazio Campagna

11 Multiple regression models 4 models per functional group with current and lagged weather: Model 1: Annual weather Model 2: Fall weather Model 3: Winter weather Model 4: Spring weather

12 Results Overview

13 Regression coefficient Regression coefficient Lagged Current Lagged Exotic annual GRASS Exotic annual FORBS Current Lagged Lagged Precipitation (in) Min Temperature ( F) Max Temperature ( F)

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15 Lagged weather seems particularly important 0.5 Exotic A. Forbs Native P. Grass Native P. Forbs Regression coefficient Exotic A. Grass Native A. Forbs

16 Lagged weather patterns drive abundance patterns 0.5 Exotic A. Forbs Native P. Grass Native P. Forbs Regression coefficient Exotic A. Grass Native A. Forbs Green bars = lagged weather

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18 Precipitation and minimum temperatures drive winter responses Regression coefficient Exotic A. Forbs Exotic A. Grass Native A. Forbs Native P. Grass Native P. Forbs Current Precip Lagged Precip Current Min Temp Lagged Min Temp Current Max Temp Lagged Max Temp

19 Lagged effects & current weather equally important 0.2 Exotic A. Forbs Native A. Forbs Exotic A. Grass Native P. Grass Native P. Forbs Regression coefficient Green bars = lagged weather

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21 Lagged precipitation and current temperatures drive spring functional group response Regression coefficient Exotic A. Forbs Exotic A. Grass Native A. Forbs Native P. Grass Native P. Forbs Current Precip Lagged Precip Current Min Temp Lagged Min Temp Current Max Temp Lagged Max Temp

22 0.4 Spring lagged precipitation is very important Exotic A. Forbs Native A. Forbs Regression coefficient Exotic A. Grass Green bars = lagged weather

23 Current and lagged weather equally important Fall Season Winter Current Weather Lagged Weather Spring 0% 20% 40% 60% 80% 100% % of total significant effects summed across season

24 What We Know Now lagged effects = weather + indirect effects community composition= current effects + lagged effects Photo: Nomadic Lass

25 Overview Broader applications

26 Environmental niche Hotter, drier Exotic Annual Forbs Native Perennial Grasses Native Perennial Forbs Climate change and functional groups? Native Annual Forbs Exotic Annual Grasses Colder, wetter

27 Managing for production Functional Group Fall Winter Spring Exotic A. Grass Warm Lagged Temp Low Precip, Low Temp High Precip, Mild Temp Exotic A. Forb Low Precip, Extreme Temps Mild Temp Low Precip, High Temp

28 Managing for diversity Functional Group Fall Winter Spring Native A. Forbs - High Precip Low Rainfall, Low Temp Native P. Forbs Lagged High Precip Low Precip + Low temp - Native P. Grasses High Precip and more Extreme Weather Low Precip & Low temp -

29 Thank you!! Dr. Emily Farrer, Dr. James Bartolome, Bartolome s lab, Dr. Suding s lab, URAP students, and East Bay Parks