Effects of Tanglehead ( Heteropogon contortus ) Invasion on Soil Microbial Communities in the Texas Coastal Sandsheet Joshua Grace 1 Invasive Grass Research Specialist D. B. Wester 1, V. Acosta-Martinez 2, S. Rideout-Hanzak 1, J.A. Ortega-S1 1 Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, TX 2 USDA-ARS-Cropping Systems Research Laboratory, USDA, Lubbock, TX Introduction • Biological species invasion poses a great threat to biodiversity – Exotic species – Native species acting invasively • Grasses – Competitive dominance ↓ Nave plant growth Species diversity Species richness Introduction Cascading effects on ecosystems • South exas – Old World bluestem – Buffelgrass – $leingrass – Lehmann’s lovegrass Potential impacts on livestock production – Guineagrass anglehead (Heteropogon contortus (L.* Link, Introduction • anglehead (Heteropogon contortus (L.* Link, • Native. warm season. perennial bunchgrass • Dense monotypic stands0 litter accumulation • Provides key wildlife habitat • 1ni2ue situation for So. exas landowners – Bobwhite 3uail http400www.texasbeyondhistory.netl – Whitetail Deer C$WRI anglehead Research • Current Research – Control and management – Production and phenology – Seed viability and longevity – Ecosystem processes • Nutrient processes • Soil microbial dynamics – Community Si6e (biomass C. N, – Community Composition Study Area • C$WRI cooperating ranch – 8im 9ogg County – Approx. 29 miles south of 9ebbronville. X Native Community Tanglehead/Native Mix Tanglehead Dominated 8 Native. 7 Mix. 3 Invaded ( n A 18, Methodology • Collected 3 soil cores from each site – AC9ori6on (0C10E,. Delmita and Nueces – Mixed to form 1. 450 g combined sample from each site (nA18, for analysis – 2013. 2014. 2015 Native Community Tanglehead/Native Mix Tanglehead Dominated MethodologyMSoil Analyses • Microbial Biomass Carbon ( MBC , and Nitrogen ( MBN, – Chloroform fumigation extractionCmethod • (Brookes et al. 1985 H Iance et al. 1987, – mg C kg -1 soil . and mg N kg -1 soil • Microbial Community Composition – Fatty Acid Methyl Ester ( FAME , profiling • (SchutterH Dick 2000, – Fatty acids identified H compared by retention times and peak areas to components of MIDI standards – %L based on nmol gC1 soil ResultsC Microbial Community Si6e 1. Repeated Measures, Mixed Model ANOVA • MBC4 Treatment x Year: P = 0.0077 – reatment x Near interaction Treatment x Year: P = 0.0077 soil) 1 P = 0.0001 P = 0.0263 – In 2013 H 2015. MBC was − lower in invaded sites than P = 0.9053 native sites a b c a a a a ab ab 0 100 200 300 MBC (mg kg MBC (mg 2013 2014 2015 Tanglehead Mixture • MBN4 Native – Iery weak interaction effects Treatment x Year: P = 0.0688 soil) P = 0.1320 1 – MBN was greater in native − P = 0.0039 P = 0.7978 sites than invaded sites during 2013 a a b a a a a a a 0 2 4 6 8 MBN (mg kg MBN (mg 2013 2014 2015 ResultsC Microbial Community Composition • Nonmetric Multidimensional Scaling Ordination • 1sing microbial indicators • GO. GC. Actinomycetes. Fungi 2013 2014 2015 MDS Axis 2 MDS Axis 2 MDS Axis 2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 MDS Axis 1 MDS Axis 1 MDS Axis 1 ResultsC Microbial Community Composition • Nonmetric Multidimensional Scaling Ordination 2013 Gn 2014 2015 N M M GPAc FUN N M MDS MDS 2 Axis MDS Axis 2 Axis MDS N 2013 2014 2015 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 -0.2 -0.1 0.0 0.1 0.2 MDS Axis 1 MDS Axis 1 2013 2014 2015 Native Mixture anglehead ResultsC Microbial Community Comp. Multivariate Analyses • MANOIA Fu Fungi – reatment4 P A 0.0487 • Invaded A Native4 P A 0.0120 GOGpeg – Near4 P P 0.0001 Ac GCGneg 0.10.1 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 1 2 3 Fu Fungi 2013 2014 2015 2013 2014 2015 GOGpeg • GO. Actinomycetes. and fungi increase • Likely a precipitation factor AcAc GCGneg Native Mixture Tanglehead 0.10.1 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 1 2 3 • GO and Actinomycetes decrease and fungi Heco Mixture Native increases ResultsC Fungi4Bacteria Ratio Repeated Measures, Mixed Model ANOVA • Fungi4Bacteria Ratio Fungi:Bacteria Ratio • reatment effects ( P = 0.0183, – Invaded A Mixture Native Mixture – Invaded > Native Heco – Mixture > Native a b b 0.60 0.70Native 0.80 Mixture Heco • Near effects ( P A 0.0001, – 2013 A 2014 20132013 – 2015 Q 2013 20142014 20152014 – 2015 Q 2014 a a b 0.5 0.7 0.9 201320122014 20132015 2014 Conclusions • Along this invasion gradient4 Microbial Community si6e and composition differed in tanglehead vs. native sites • angleheadCinvaded sites showed lower microbial biomass C and N in 2 of the 3 years • (smaller microbial community si6e, • Implications on soil health and functions (soil respiration. soil productivity. and health, Conclusions • Along our invasion gradient. we did see differences in microbial community si6e and composition in tanglehead sites vs. native sites – 9ad higher fungi4bacteria ratios than native sites • Shift to more fungiCdominated microbial communities may represent changes in nutrient levels • Can result in shifting of the system. including conditions favoring invasive plants Conclusions • We observed changes in mean microbial composition Native Mixture anglehead G+, Actinomycetes Fungi ↑MBC and MBN ↓MBC and MBN • Patterns in variation of microbial composition – Both a RyearE and RinvasionE pattern – Invasion pattern consistent within years – LeftCtoCright gradient Conclusions • Soil organisms4 – Play vital roles in carrying out ecosystem processes such as decomposition and nitrogen cycling – Changes in soil community composition and si6e may be particularly important in S. X ecosystems due to fluctuations in resource availability – Compositional changes may indicate changes in microbial diversity • Results indicate negative changes in soil 2uality and microbial functioning that are key factors when undergoing restoration practices Current Research • What causes this change in microbial communitiesS – Residual dry matterS – Introduction of individual plantS • 9ow can we manage and controlS – Gra6ing. burning. disking. herbicideS – All of the aboveS Acknowledgements • 1SDACARSCCSR Laboratory • he Rotary Club of Corpus ChristiC9arvey Weil • Mr. 9enry 9ammon • Mr. Renee’ Barrientos • he Coates family • South exas 3uail Coalition • he Brown Foundation 3uestionsS.