University of Colorado, Boulder CU Scholar Ecology & Evolutionary Biology Graduate Theses & Ecology & Evolutionary Biology Dissertations Spring 1-1-2015 Long Term Restoration Projects: Invasive Species Caused Feedbacks Above and Belowground Akasha May Faist University of Colorado Boulder, [email protected] Follow this and additional works at:https://scholar.colorado.edu/ebio_gradetds Part of theEcology and Evolutionary Biology Commons, and theForest Biology Commons Recommended Citation Faist, Akasha May, "Long Term Restoration Projects: Invasive Species Caused Feedbacks Above and Belowground" (2015).Ecology & Evolutionary Biology Graduate Theses & Dissertations. 67. https://scholar.colorado.edu/ebio_gradetds/67 This Dissertation is brought to you for free and open access by Ecology & Evolutionary Biology at CU Scholar. It has been accepted for inclusion in Ecology & Evolutionary Biology Graduate Theses & Dissertations by an authorized administrator of CU Scholar. For more information, please contact [email protected]. LONG TERM RESTORATION PROJECTS: INVASIVE SPECIES CAUSED FEEDBACKS ABOVE AND BELOWGROUND by AKASHA FAIST B.S., Southern Oregon University, 2004 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirement for the degree of Doctor of Philosophy Department of Ecology and Evolutionary Biology 2015 This dissertation entitled: Long term restoration projects: Invasive species caused feedbacks above and belowground written by Akasha Faist has been approved for the Department of Ecology and Evolutionary Biology (Sharon K. Collinge) (Nichole N. Barger) (Kendi F. Davies) (Paula J. Fornwalt) (Timothy R. Seastedt) Date The final copy of this thesis has been examined by the signatories, and we Find that both the content and the form meet acceptable presentation standards Of scholarly work in the above mentioned discipline. Faist, Akasha (Ph.D., Ecology and Evolutionary Biology) Long term restoration projects: Invasive species caused feedbacks above and belowground Dissertation directed by Professor Sharon K. Collinge ABSTRACT Invasive species are considered one of the top five threats to biodiversity worldwide and when established can quickly degrade a system. In response to this degradation a large number of ecological restoration projects have been implemented to mitigate the effects of invasion. Using a long term vernal pool restoration project that has documented invasive encroachment over time, I sought to tease apart the mechanisms underlying exotic plant invasion through exploration of positive feedbacks in both above and belowground plant communities. My results demonstrated that a thick litter layer deposited by the invasive species not only decomposed at a slower rate than native litter, but also strongly hindered native species abundance. This invasive litter layer created a positive feedback that allowed for invasive species recruitment while hindering the majority of natives from reaching the aboveground vegetation. However, vernal pool native species were maintained at continually high densities in the seed bank and the abundant aboveground invasives had a much lower presence belowground. These results were corroborated by my comparisons of the existing seed bank community to the historical aboveground vernal pool vegetation (5-8 years prior) versus more recent aboveground vegetation (1-3 years prior). Here I found a strong legacy effect in seed banks; i.e., seed banks had a composition with greater similarity to the historical aboveground vegetation than to the more recent aboveground vegetation. Finally, to test if similar relationships as those observed for iii above and belowground vernal pool vegetation were present in other, more widespread systems, I conducted a seed bank study in three Colorado conifer forests types. The forests had all undergone a mechanical fuels reduction treatment aimed at restoring historical fire regimes. Under thick mulch layers of treated woody materials, the seed banks tended toward increased density when compared to the untreated, but seed banks generally did not differ among treatments. These results coupled with the vernal pool findings show that the aboveground vegetation and seed banks are often quite divergent. Therefore when implementing and monitoring a long term restoration project it is important to understand drivers of both the above and belowground responses to fully understand restoration success. iv ACKNOWLEDGEMENTS First and foremost I would like to thank my major advisor Dr. Sharon Collinge for all of her support and guidance. Her ability to accomplish amazing feats while maintaining an admirable humility and genuine kindness is second to none. Her support goes well beyond her strong ecological understanding of vernal pool systems as she has been a mountain of encouragement in every step of my tenure of this doctoral program. I would also like to thank Dr. Nichole Barger for her help with not only structuring my research, but serving to broaden my teaching and writing skills with which I will undoubtedly refer back to for the rest of my career. I thank Dr. Tim Seastedt for his ability to look at the big picture of a question which has been incredibly helpful in developing my research questions. I thank Dr. Kendi Davies for her deep knowledge of theory and practice in plant ecology which has motivated me to integrate these topics into my own research. I would also like to thank Dr. Paula Fornwalt for her countless hours spent helping write grants, develop research ideas and all of our times botanizing in the field. I have been fortunate to receive a number of grants that have aided in my research and would like to acknowledge the Garden Club of America, Society of Wetland Scientists, California Native Plant Society, American Association of University Women, The University of Colorado EBIO departmental research grant and the National Science Foundation. I also thank all of the undergraduate student help I have received with field and lab work. Finally, the contents of this document were substantially improved by suggestions from Dr. Scott Ferrenberg and the University of Colorado EBIO graduate writing cooperative. v CONTENTS CHAPTER 1 INTRODUCTION 1.1. Restoration Ecology…………………………………………………………………………………………1 1.2 Ecological Theory……………………………………………………………………………...…………….2 1.2.1 Alternative States…………………………………………………………………...………….…2 1.2.2 Storage Effect and Ecological Filtering……………………………………….………………….3 1.3 Study Systems…………………………………………………………………………………………….….4 1.3.1 Seed Banks……………………………………………………………...………………………...5 1.3.2 Vernal Pools……………………………………………………………...……………………….6 1.3.3 Colorado Conifer Forest Mastication…………………………………….……………………….7 1.4 Research Outline……………………………………………………………………..………………………8 CHAPTER 2 POSITIVE FEEDBACKS OF LITTER PROMOTE ALTERNATIVE STATES 2.1 Abstract………………………………………………………………………………………………………9 2.2. Introduction……………………………………...……………………………………………………..…..10 2.3 Methods…………………………………………………………………………………………………..…14 2.3.1 Study Site and Experimental Design………………………………………………………..…...14 2.3.2 Inundation……………………………………………………………………………………..…16 2.3.3 Litter Decomposition………………………………………………………………………..…...17 2.3.4 Litter Manipulations………..……………………………………………………..……………..18 2.3.5 Soil Properties……….……………………………………………………………….………….19 2.3.6 Statistical Analyses……………………………………………………………………………....20 2.4 Results…………………………………………………………………………………………………..…..23 2.4.1 Inundation……………………………………………………………………………………..…23 2.4.2 Litter Decomposition………………………………………………………………………….....24 2.4.3 Litter Manipulations……………………………………………………………………….…….26 2.4.4 Soil Properties…………….……………………………………………………………………..27 2.5 Discussion…………………………………………………………………………………………..………29 2.5.1 Inundation………………………………………………………………………………..………29 2.5.2 Litter Decomposition………………………………………………………………..…………...30 2.5.3 Litter Manipulations…………………………………………………………………….……….31 2.5.4 Soil Properties……………………………………………………………………………….…..33 2.6 Conclusions……………………………………………………………………………………………..…..33 CHAPTER 3 SEED BANK COMPOSITION VARIES ALONG INVASION AND INUNDATION GRADIENTS IN VERNAL POOL WETLANDS 3.1 Abstract………………………………………………………………………………………………....…..36 3.2 Introduction……………………………………………………………………………………………..…..37 3.3. Materials and Methods………………………………………………………………………..……………40 3.3.1 Study Area…………………………………………………………………………………….....40 3.3.2 Study Design……………………………………………………………………………….……40 3.3.3 Data Collection (field and greenhouse)……………………………………………………..…...41 3.3.4 Statistical Analyses……………………………………………………………………..………..42 3.4 Results…………………………………………………………………………………………………..…..44 3.4.1 Community Metrics………………………………………………………………………..…….44 vi 3.4.2 Total Seed Densities……………………………………………………………………..………46 3.4.3 Invasive and Native Seed Densities………………………………………………………….….48 3.4.4 Greenhouse Inundation Treatments………………………………..………………………..….50 3.5 Discussion…………………………………………………………………………………………………..52 3.5.1 Community Metrics……………………………………………………………..……………….52 3.5.2 Total Seed Densities………………………………………………………………………..……53 3.5.3 Invasive and Native Species Densities………………………………………………………..…54 3.5.4 Greenhouse Inundation Treatments……………………….……………………………..…….56 3.6 Conclusions………..………………………………………………………………………………………..57 CHAPTER 4 BANKING ON THE PAST: SEED BANKS AS A RESERVOIR FOR RARE AND NATIVE SPECIES IN RESTORED VERNAL POOLS 4.1 Abstract…………………………………………………………………………………………………..…59 4.2 Introduction………………………………………………………………………………………………....60 4.3 Methods………………………………………………………………………………………………..……63 4.3.1 Study Site and Experimental Design………………………………………………………..…...63 4.3.2 Seed Bank Sampling……………………………………………………………………..………64 4.3.3 Seedling Emergence…………………………………………………………………….....…….64 4.3.4 Aboveground Plant Community………………………………………………………..………..65 4.3.5 Data Analysis…………………………………………………………………………………….66 4.4 Results…………………………………………………………………………………………………..…..68 4.4.1 Species Accumulation and Diversity…………………………………………………..………...68 4.4.2 Community Structure and Species Abundance………………….………………………………70 4.4.3 Introduced and Native Species Abundance…………………………………………………..….73 4.5 Discussion………………………………………………………………………………………..…………74 4.5.1 Species Accumulation and Diversity………………………………………………………..…...75 4.5.2 Community Structure and Species Abundance……………………………………………….…77 4.5.3 Introduced and Native Species Abundance………………………………………………..…….78 4.6 Conclusions………………………………………………………………………………………………....79 CHAPTER 5 IMPACTS OF MASTICATION, A FUEL REDUCTION TREATMENT, ON SOIL SEED BANKS IN THREE COLORADO (USA) CONIFER FOREST TYPES 5.1 Abstract……………………………………………………..………………………………………..……..80 5.2 Introduction………………………………………………..……………………………………………..…80 5.3 Methods……………………………………………………..……………………………………………....84 5.3.1 Study Area and Design……………………………………….……………………………..…...84 5.3.2 Field Sampling….…………………………………………….……………………………..…...85 5.3.3 Greenhouse Methods………………………………………….………………………………....86 5.3.4 Molecular Methods…………………………………………………………….……………..….87 5.3.5 Statistical Analyses…………………………………………………………….………………...88 5.4 Results……………………………………………………………………………………..…………..……89 5.4.1 Seed Banks…………………………………………………………………….…………….…..89 5.4.2 Aboveground Vegetation and Mulch Depths………………………………….……………..….93 5.5 Discussion…………………………………………………………………………………..……………....95 5.5.1 Seed Banks……………………………………………………………………….………….…..95 5.5.2 Aboveground Vegetation and Mulch Depths…………………………………….…………….97 CHAPTER 6 CONCLUSIONS………………………………………………………………………….....…99 BIBLIOGRAPHY………………………………………………………………………………………..…..102 vii LIST OF TABLES Table 2.1 Plant tissue percent Nitrogen, Carbon, Cellulose and Lignin and associated Carbon:Nitrogen and Lignin:Nitrogen ratios for common species found within the confines of the vernal pools and adjacent edges……………………………………………………….……..26 Table 2.2 Invasive and native richness and percent abundance by pool type as determined by the presence or absence of a measurable litter layer. Each species group, invasive or native, divided by pool type was tested for differences through a Mann Whitney U test………………………..27 Table 2.3 Soil metrics for field collected soil samples as determined by pool type. Letters indicate comparisons that displayed a significant difference between pool types as determined by a post hoc Tukey HSD test. If no significant differences were observed no letters were added..28 Table 3.1 Comparison testing through a PERMANOVA to understand the effect of three factors (pool type, plot location and inundation treatment) on seed bank communities……………..….45 Table 3.2 Determining seed density variation with a three factor ANOVA where Pool type, location within a pool and greenhouse treatments were the determining variables and seed density (seeds / kg soil) the response variable. Only Pool type and Location were significant factors and no interaction terms were present (P ≤ 0.05)…………………………………..……46 Table 3.3 Seed bank diversity estimates of pool type. All calculations represent mean diversity indices with letters indicationd significant differences (ANOVA followed by a Tukey’s HSD pariwise test, P<0.05)……………………………………………………………………….……48 Table 3.4 Species level responses to greenhouse inundation germination trials. Species in bold indicate significant differences in treatment types (Wilcoxon rank-sum test, P<0.05)………….51 Table 4.1 Mantel test for association between seed bank and aboveground vegetation communities……………………………………………………………………………………...71 Table 4.2 Percentage of the community comprised of native and introduced plant species categorized as rare (species combined), intermediate abundance, and common in aboveground and seed bank vernal pool vegetation………………………………………………..…………..73 Table 5.1 Raw counts of seeds segregated by family and genus (identified to species if positive identification was available). Each family has the total number of seeds observed including individuals that were identified further. *Denotes identified non-native species………………..92 viii LIST OF FIGURES Figure 1.1 Ball-in-cup diagram where the ball represents the biotic state characteristics (variables) and the surface represents the environmental conditions (parameters). To reach an alternative stable state the two primary pathways are either a shift in the variables or the parameters (Adapted from Beisner et al. 2003)…………………………………………………...3 Figure 2.1 Invasive and native species cover and richness by the three difference pool types. Letters indicate significant difference as determined by a non-parametric pairwise Wilcoxon rank sum tests corrected by False Discovery Rate test to reduce type I error. Center line represents the median value of the metric tested and the box surrounding the median represents the second and third quartiles…………………………………………………………………………………….16 Figure 2.2 Mean inundation differences between pool types and location by winter wet season. Capital letters indicate significant differences between pool types for the associated year and lower case letters indicate significant differences between inundation locations within a single pool type. All data were determined through an ANOVA and post hoc Tukeys HSD test. Error bars indicate a SE of ±1………………………………………………………………………….23 Figure 2.3 Percent mass of L. multiflorum lost due to decomposition for the a) winter wet season (2012-2013) and b) summer dry season (2013). Inundation gradient placement was not significant for either of these tests so displayed pool type and litter placement. Capital letters indicate significant differences across all pool types and lowercase letters indicate differences in litter placement. Litter placement did not have any significance for the winter wet season so no letters are present. All analyses utilized an ANOVA and a post-hoc Tukeys HSD test for significance. Error bars represent a SE of ±1. …………………………………………………..26 Figure 3.1 NMDS plots showing how vegetation communities vary in relation to pool type, location within a pool and greenhouse inundation treatments. After eight runs the stress solution was reached at 0.196 using a Bray Curtis distance matrix………………………………………45 Figure 3.2 Total seed densities as determined by pool type and location. Panel “b” and “c” are both naturally occurring pools with the aboveground dominated by either invasive or native species while the constructed pools “a” were created for restoration purposes and are primarily dominated by invasive species aboveground. Constructed pools contained significantly lower seed densities than either of the naturally occurring pools. Letters indicate significance (ANOVA with Tukey’s HSD pairwise tests, P<0.05) with a standard error of ±1…………………………47 Figure 3.3 Invasive species seed densities as determined by pool type and location. Panel a and b are both naturally occurring pools with the aboveground dominated by either invasive or native species while the constructed pools were created for restoration purposes and are primarily dominated by invasive species aboveground. For invasive seeds each pool type was significantly different from one another. Lowercase letters indicate significance between pool location within a pool type (ANOVA with Tukey’s HSD pairwise tests, P<0.05) with a standard error of ±1….49 ix