Post-fire response of bryophytes in association with understory vascular plants in the Lost Pines Ecosystem of Central Texas Ingrid Karklins Ingrid Karklins An Undergraduate Research Scholars Thesis ingrid.karklins@gmail.com
INTRODUCTION Bryophytes (mosses, liverworts and hornworts) are earlyresponders to disturbances such as fire 1 Generally not included in post-fire vascular plant research 2 In 1954, Eula Whitehouse 3 noted the lack of research on Texas moss ecology This is still true today Ditrichum pallidum 1 Duncan and Dalton. 1982 2 Ryoma, R. and S. Laaka-Undberg. 2005 3 Whitehouse 1954
Bryophytes can grow on mineral soil Can reproduce as soon as moisture is available May play an important role in the success of forest restoration Particularly after fire 2,3,1. 1 Kayes et al. 2010 2 de las Heras-Ibáñez et al. 1991 3 Ryoma and Laaka-Undberg. 2005 Funaria hygrometrica
OBJECTIVES
OBJECTIVES 1. What are the site conditions that impact species presence and composition? Hypotheses: a) Litter will limit plant cover b) Canopy shade will limit plant cover c) Soil moisture will limit plant cover
OBJECTIVES 2. Will bryophyte and vascular plant dominance be different in burned and unburned areas? Hypothesis Plant dominance will differ between burned and unburned areas
OBJECTIVES 3. Are there associated groups of species found in burned versus unburned areas? Hypothesis Burned and unburned areas will have distinctly different vascular plant and bryophyte communities and indicator species
METHODS
STUDY AREA Two adjacent watersheds in the Bastrop Lost Pines Ecosystem
The Price Creek watershed study area was heavily burned in the 2011 Bastrop County Complex Fire
The Spicer Creek watershed was unburned, but displayed evidence of pine beetle damage in some areas
TRANSECTS Stratified random sampling method 5 transects in each of the two watersheds 5 quadrats per riparian and upland strata
COVER ESTIMATES Plant cover determined by percent cover estimates in three strata: canopy above 15 feet understory -- 1.5 to 15 feet groundcover below 1.5 feet
RESULTS
LITTER Very poor soil conditions in burned areas Very thin litter Litter up to 6 thick in unburned areas 100 90 80 Litter % cover 70 60 50 40 30 20 10 0 Riparian Burned Upland Burned Riparian Unburned Upland Unburned Litter percent cover in burned and unburned riparian and upland quadrats. Error bars are standard errors (n = 25 quadrats per category).
LITTER HYPOTHESIS Weak positive relationship between litter cover and plant cover in burned areas Groundcover plant % cover 100 90 80 70 60 50 40 30 20 10 0 R² = 0.1075 0 20 40 60 80 100 Litter % cover Litter percent compared to groundcover plant percent cover in burned quadrats. No evidence to support the hypothesis that litter limits plant cover at ground level
SOIL MOISTURE Differences in soil moisture Higher in burned areas than unburned areas Higher in riparian areas than in uplands Soil moisture levels were extremely low at the time of the study 14 12 Soil moisture 10 8 6 4 2 0 Riparian Burned Upland Burned Riparian Unburned Upland Unburned Soil moisture in burned and unburned riparian and upland quadrats. Error bars are standard errors (n = 25 quadrats per category).
SOIL MOISTURE HYPOTHESIS Plant cover at ground level and soil moisture Burned areas: Mixed trend among transects with no clear relationship (p > 0.05). Unburned areas No relationship (p > 0.05). No evidence to support the hypothesis that soil moisture limited plant abundance at ground level
CANOPY SHADE HYPOTHESIS Canopy cover in unburned areas showed a weakly negative relationship to plant cover at ground level that was not significant No evidence to support the hypothesis that increased canopy shade in unburned areas results in low plant cover at ground level
GROUNDCOVER 600 Groundcover species % cover 500 400 300 200 100 0 Burned Riparian Burned Upland Unburned Riparian Unburned Upland Total percent groundcover of bryophytes and most abundant vascular plant species.
Funaria hygrometrica and Ditrichum pallidum most abundant Known disturbance species BRYOPHY TES BURNED Ditrichum pallidum Funaria hygrometrica
BRYOPHY TES UNBURNED Dominated by Leucodon julaceus and Weissia controversa L. julaceus typically grows on bark substrate 1 1 Reese 1984 Leucodon julaceus
PLANT SPECIES HYPOTHESIS Species dominance in burned and unburned areas distinctly different Supports the hypotheses that bryophyte and vascular plant dominance will be different
INDICATOR SPECIES PC-ORD analysis, based on frequency for all three strata, identified 11 indicator species (Indicator value >30, p-value <0.05) MOSSES: Funaria hygrometrica* Ditrichum pallidum* Leucadon julaceus Weissia controversa GRASSES & FORBS Dichanthelium Polypremum procumbens Burned Unburned Both SHRUBS Baccharis Ilex vomitoria Juniperus virginiana* Vaccinium arboreum *Indicator value >50, p-value <0.05
Mostly unburned Unburned Mostly burned Burned PC-ORD cluster analysis
DISCUSSION Atrichum angustatum
DISCUSSION SPECIES DIVERSIT Y Groundcover in burned areas dominated by r-selected type species Aggressive colonizers High incidence of annual species 1 Vascular plant diversity higher in burned watershed Bryophyte diversity higher in unburned watershed Overall trend: groundcover vegetation diversity increased after 2011 Bastrop fires 1 During 1979
DISCUSSION BRYOPHY TES Early responders to disturbance Clearly part of ecosystem recovery processes Pioneer primary producers retain water cycle nutrients adapt to various habitats Act as nurse plants Facilitate the reintroduction of vascular plants in disturbed ecosystems 1 F. hygrometrica & D. pallidum = early seral disturbance species pave the way for post-disturbance vascular succession 1 Ren et al. 2010
Bryophyte and vascular plant interactions have an important role in the post-fire Bastrop Lost Pines Ecosystem recovery process Bryophyte association patterns can be used to determine species that are appropriate for restoration of damaged or stressed environments. 1 Bryophytes can serve as a restoration tool Primary producers set the stage for other species Particularly in riparian zones 1 Fensham and Streimann 1997
REFERENCES Brown, D. J., W. H. Nowlin, E. Ozel, I. Mali, D. Episcopo, M. C. Jones, and M. R. J. Forstner. 2014. Comparison of shor t term low, moderate, and high severity fire impacts to aquatic and terrestrial ecosystem components of a southern USA mixed pine/hardwood forest. Forest Ecology and Management 312:179-192. de las Heras-Ibáñez, J., J. Guerra, and J. M. Herranz. 1991. Changes in floristic diversity and fugacity of br yophytes in burnt sites of SE Spain. Lindbergia 17:11-16. Dietert, M. F. 1979. Studies on the gametophyte nutrition of the cosmopolitan species Funaria hygrometrica and Weissia controversa. The Br yologist 82:417-431. Duncan, D. and P. L. Dalton. 1982. Recolonisation by br yophytes following fire. Journal of Br yology 1 2:53-63. During, H. J. 1979. Life strategies of br yophytes: a preliminar y review. Lindbergia 5:2-18. Fensham, R. J. and H. Streimann. 1997. Broad landscape relations of the moss flora from inland dr y rainforest in nor th Queensland, Australia. Br yologist 100:56-64. Hardman, A. and B. McCune. 2010. Br yoid layer response to soil disturbance by fuel reduction treatments in a dr y conifer forest. Br yologist 113:235-245.
REFERENCES Kayes, L. J., P. D. Anderson, and K. J. Puettmann. 2010. Vegetation succession among and within structural layers following wildfire in managed forests. Journal of Vegetation Science 21:233-247. Reese, W. D. 1984. Mosses of the Gulf South: from the Rio Grande to the Apalachicola. Louisiana State University Press. Ren, H., G. Ma, Q. Zhang, Q. Guo, J. Wang, and Z. Wang. 2010. Moss is a key nurse plant for reintroduction of the endangered herb, Primulina tabacum Hance. Plant Ecology 209:313-320. Ryoma, R. and S. Laaka-Undberg. 2005. Br yophyte recolonization on burnt soil and logs. Scandinavian Journal of Forest Research 20: 5-6. Shaw, A. J. and B. Gof finet. 2000. Br yophyte biology. Cambridge University Press. Whitehouse, E. 1954. The mosses of Texas : foreword. Br yologist 57:53-63.
GREAT THANKS TO Dr. Georgianne W. Moore, Associate Professor, Department of Ecosystem Science and Management Dale A. Kruse, Curator, S. M. Tracy Herbarium