1 Sarah Kimball, Megan Lulow, Quinn Sorenson Native Functional Groups, Seeding Methods, and Maintenance Methods Determine Native Establishment in Trait-Based RestorationThis project was conducted by CEB in collaboration with IRC. Megan and Quinn did much of this work.Sarah Kimball, Megan Lulow, Quinn Sorenson
2 Functional Groups (species grouped by their traits) Ruderals: early seral, colonizers, annuals, high relative growth ratePerennials: late seral, competitors or stress tolerators, slower growth rateWe’re particularly interested in the performance of different functional groups of native plants used in restoration.
3 Plant Traits and Restoration Select plants based on traits (Pywell et al. 03)Communities resistant to invasion contain natives with traits similar to invasives (limiting similarity hypothesis, Emery 07)Plant natives with a range of traits and esp. with traits similar to invasives (Funk et al. 08)In restoration, plant traits are important to consider in deciding what species to use in projects. For example, one might think about where a plant falls on Grime’s triangle, does it have traits that allow it to be a good colonizer, a stress-tolerator, or a good competitor.In trait-based restoration, plants are selected based on whether they have traits that enable them to establish and persist in the community.Intact communities are thought to be more resistant to invasion by non-native, invasive species when they contain natives with traits similar to invasives, this has been tested in restoration projects where communities are assembled that have different trait combinations.
4 Research QuestionsWhat native functional group (ruderals, perennials, or a mix) results in the best native establishment?Mechanics of restoration (Seeding Method? Weed removal methods?)Although people are investigating how different functional groups used in restoration may interact with invasive species, we’re not aware of many studies focusing on how the different native functional groups may interact with one another during establishment of the native community.There are also on-going questions in restoration about the best method of seeding and of reducing the cover of non-natives. These may differ depending on the native functional group and may be complicated by mixing groups.
5 West Loma Ridge Grow and kill cycle: Mow Nov 2009 Spray Feb2010 Mow June 2010Spray Nov 2010Seed Dec 2010West Loma Ridge on the Irvine Ranch, area that was grazed and burned in the past and had a high cover of non-native species.
8 Maintenance Treatments Every 4 weeks-standardized time/plot 1. Man/Mow: Hand Weeding (Manual) & weed-eating (Mow)First hand weeding, later weed eating to height of natives2. Wick: Herbicide-Wicking
9 6 replicates of all treatment combinations Experimental Design6 replicates of all treatment combinationsNative annuals: Malacothrix, Deinendra, Calandrinia, Phacelia, Escholtzia, LupinusNative perennials: Artemisia, Eriogonum, Encelia, Salvia, Lotus, Leymus
10 Data Collection & Analysis Emergent Seedlings- One month post-seedingNumber of individuals- Late springCover- Late spring (point intercepts)Seed set & height - SummerMixed-model ANOVAs with block as a random factor and seeding method, maintenance treatment, and seed mix as fixed factors
11 Emergent Seedlings in Feb. Hand seeding resulted in greater emergence than drill seeding (F1,102=24.03, P<0.0001).More perennial seedlings than ruderals (F1,102=5.9, P=0.004).
12 Emergent Seedlings: Seed Mixes Consider changing axis of native ruderals to point out higher germination of perennials.• More perennials when seeded alone than in mixed group (F1,63=5.87, P=0.0183).
13 Emergent Non-Native Seedlings in Feb. Hand seeding resulted in greater germination of BRNI (F1,97=55.37, P<0.001).Drill seeding resulted in greater germination of invasive grasses (F1,97=11.58, P=0.01).
14 Cover in Late Spring: Maintenance Techniques Wick was most effective at reducing non-natives.Native Cover increased with weed removal (F2,85=42.06, P<0.0001).
15 Late Spring Cover: Seed Mixes Ruderals had greater overall cover during first growing seasonEach functional group had greater cover when planted alone (Perennials F1,55=36.31, P<0.0001, Ruderals F1,55=10.38, P=0.002)
16 Late Spring Density: Seed Mixes Perennials had greater overall density during first growing seasonEach group had greater density when planted alone (Perennials F1,55=29.67, P<0.0001, Ruderals F1,60=8.62, P=0.005)
17 Late Spring: Ordination of Plots in Species Space Salvia apiana correlated with axis 1 (r=0.962)Phacelia ciliata negatively correlated with axis 1 (r=-0.72)
18 Native Species Seed Production Also mention that annuals had higher reproduction in the wich treatment plots.Phacelia had reduced seed production when grown with perennials (F1,40=6.68, P=0.014)Malacothrix had reduced seed production when grown with perennials (F1,40=11.9, P=0.002).
19 Reproduction & Size of Perennials Eriogonum only reproduced in the wick treatment plots without ruderals.ERFA individuals were taller in plots without ruderals (F1,32=9.21, P=0.005).Lemus was larger in plots without ruderals (F1,23=4.63, P=0.04).
20 Conclusions Each native functional group did best alone Hand Seeding resulted in more native seedlings (and more BRNI)Wick herbicide removed more non-natives and resulted in higher reproduction of native species, but man/mow resulted in higher cover and density of natives
21 Implications for Trait-based Restoration Importance of considering interactions among native functional groups (not just between natives and invasives)Contrary to coexistence theory, greater trait diversity increased competitionSeeding methods
22 Next Steps Collecting data this year on germination in plots. Return to marked perennials to measure survivorship, size, & fecunditySeeded much larger area surrounding initial experiment.