Abstract
Woody encroachment—the spread of woody vegetation in open ecosystems—is a common threat to grasslands worldwide. Reversing encroachment can be exceedingly difficult once shrubs become established, particularly clonal species that resprout following disturbance. Single stressors are unlikely to reverse woody encroachment, but using multiple stressors in tandem could be successful in slowing or reversing encroachment. We explored whether increasing fire frequency in conjunction with multi-year drought could reduce growth and survival of encroaching shrubs in a tallgrass prairie in northeastern Kansas, USA. Passive rainout shelters (~ 50% rainfall reduction) were constructed over mature clonal shrubs (Cornus drummondii) and co-existing C4 grasses in two fire treatments (1-year and 4-year burn frequency). Leaf- and whole-plant level physiological responses to drought and fire frequency were monitored in shrubs and grasses from 2019 to 2022. Shrub biomass and stem density following fire were unaffected by five years of consecutive drought treatment, regardless of fire frequency. The drought treatment had more negative effects on grass leaf water potential and photosynthetic rates compared to shrubs. Shrub photosynthetic rates were remarkably stable across each growing season. Overall, we found that five consecutive years of moderate drought in combination with fire was not sufficient to reduce biomass production or stem density in an encroaching clonal shrub (C. drummondii). These results suggest that moderate but chronic press-drought events do not sufficiently stress encroaching clonal shrubs to negatively impact their resilience following fire events, even when fire frequency is high.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Data availability
Data will be made available through the Konza Prairie Biological Station (KPBS) Long-Term Ecological Research (LTER) website (http://lter.konza.ksu.edu/data) (Keen and Nippert 2024).
Code availability
Not applicable.
References
Abrams MD (1986) Historical development of gallery forests in northeast Kansas. Vegetation 65(1):29–37
Acharya BS, Kharel G, Zou CB, Wilcox BP, Halihan T (2018) Woody plant encroachment impacts on groundwater recharge: A review. Water 10(10):1466. https://doi.org/10.3390/w10101466
Allen MS, Palmer MW (2011) Fire history of a prairie/forest boundary: more than 250 years of frequent fire in a North American tallgrass prairie. J Veg Sci 22(3):436–444. https://doi.org/10.1111/j.1654-1103.2011.01278.x
Anadón JD, Sala OE, Turner BL, Bennett EM (2014) Effect of woody-plant en- croachment on livestock production in North and South America. Proc Natl Acad Sci USA 111(35):12948–12953. https://doi.org/10.1073/pnas.1320585111
Bachle S, Griffith DM, Nippert JB (2018) Intraspecific trait variability in Andropogon gerardii, a dominant grass species in the US Great Plains. Front Ecol Evol 6:217
Brandt JS, Haynes MA, Kuemmerle T, Waller DM, Radeloff VC (2013) Regime shift on the roof of the world: Alpine meadows converting to shrublands in the southern Himalayas. Biol Conserv 158:116–127. https://doi.org/10.3389/fevo.2018.00217
Briggs JM, Knapp AK, Brock BL (2002) Expansion of woody plants in tallgrass prairie: a fifteen-year study of fire and fire-grazing interactions. Am Midl Nat 147(2):287–294. https://doi.org/10.1674/0003-0031
Briggs JM, Knapp AK, Blair JM, Heisler JL, Hoch GA, McCarron LMS (2005) An ecosystem in transition: causes and consequences of the conversion of mesic grassland to shrubland. Bioscience 55(3):243–254. https://doi.org/10.1641/0006-3568(2005)055[0243:AEITCA]2.0.CO;2
Brunsell NA, Nippert JB, Buck TL (2014) Impacts of seasonality and surface heterogeneity on water-use efficiency in mesic grasslands. Ecohydrology 7(4):1223–1233. https://doi.org/10.1002/eco.1455
Carroll CJ, Slette IJ, Griffin-Nolan RJ, Baur LE, Hoffman AM, Denton EM, Gray JE, Post AK, Johnston MK, Yu Q, Collins SL (2021) Is a drought a drought in grasslands? Productivity responses to different types of drought. Oecologia 197(4):1017–1026. https://doi.org/10.1007/s00442-020-04793-8
Christensen JH, Hewitson B, Busuioc A, Chen A, Gao X, Held I, Jones R, Kolli RK, Kwon WT, Laprise R, Magaña Rueda V (2007) Regional climate projections. Chapter 11
Collins SL (1992) Fire frequency and community heterogeneity in tallgrass prairie vegetation. Ecology 73(6):2001–2006
Collins SL, Calabrese LB (2012) Effects of fire, grazing, and topographic variation on vegetation structure in tallgrass prairie. J Veg Sci 23:563–575. https://doi.org/10.1111/j.1654-1103.2011.01369.x
Collins SL, Nippert JB, Blair JM, Briggs JM, Blackmore P, Ratajczak Z (2021) Fire frequency, state change and hysteresis in tallgrass prairie. Ecol Lett 24(4):636–647. https://doi.org/10.1111/ele.13676
Connell RK, Nippert JB, Blair JM (2020) Three decades of divergent land use and plant community change alters soil C and N content in tallgrass prairie. J Geophys Res. https://doi.org/10.1029/2020JG005723
Cook BI, Ault TR, Smerdon JE (2015) Unprecedented 21st century drought risk in the American Southwest and Central Plains. Sci Adv 1(1):e1400082. https://doi.org/10.1126/sciadv.1400082
Craine JM, Nippert JB (2014) Cessation of burning dries soils long term in a tallgrass prairie. Ecosystems 17(1):54–65. https://doi.org/10.1007/s10021-013-9706-8
Dai A (2013) Increasing drought under global warming in observations and models. Nat Clim Chang 3:52–58. https://doi.org/10.1038/NCLIMATE1633
DeSantis RD, Hallgren SW, Stahle DW (2010) Historic fire regime of an upland oak forest in south-central North America. Fire Ecology 6(3):45–61. https://doi.org/10.4996/fireecology.0603045
Easterling DR, Meehl GA, Parmesan C, Changnon SA, Karl TR, Mearns LO (2000) Climate extremes: observations, modeling, and impacts. Science 289:2068–2074. https://doi.org/10.1126/science.289.5487.2068
Eldridge DJ, Bowker MA, Maestre FT, Roger E, Reynolds JF, Whitford WG (2011) Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis. Ecol Lett 14(7):709–722. https://doi.org/10.1111/j.1461-0248.2011.01630.x
Engle DM, Bodine TN, Stritzke JF (2006) Woody plant community in the cross timbers over two decades of brush treatments. Rangel Ecol Manage 59(2):153–162. https://doi.org/10.2111/05-112R2.1
Fay PA, Carlisle JD, Danner BT, Lett MS, McCarron JK, Stewart C, Knapp AK, Blair JM, Collins SL (2002) Altered rainfall patterns, gas exchange, and growth in grasses and forbs. Int J Plant Sci 163(4):549–557. https://doi.org/10.1086/339718
Fay PA, Carlisle JD, Knapp AK, Blair JM, Collins SL (2003) Productivity responses to altered rainfall patterns in a C4-dominated grassland. Oecologia 137(2):245–251. https://doi.org/10.1007/s00442-003-1331-3
Fay PA, Kaufman DM, Nippert JB, Carlisle JD, Harper CW (2008) Changes in grassland ecosystem function due to extreme rainfall events: implications for responses to climate change. Glob Change Biol 14(7):1600–1608. https://doi.org/10.1111/j.1365-2486.2008.01605.x
Ford TW, Chen L, Schoof JT (2021) Variability and transitions in precipitation extremes in the Midwest United States. J Hydrometeorol 22(3):533–545. https://doi.org/10.1175/JHM-D-20-0216.1
Formica A, Farrer EC, Ashton IW, Suding KN (2014) Shrub expansion over the past 62 years in Rocky Mountain alpine tundra: possible causes and consequences. Arctic Antarctic Alpine Research 46(3):616–631. https://doi.org/10.1657/1938-4246-46.3.616
Fox J, Weisberg S (2019) An R companion to applied regression, 3rd edn. Sage, Thousand Oaks CA
Gibbens RP, McNeely RP, Havstad KM, Beck RF, Nolen B (2005) Vegetation changes in the Jornada Basin from 1858 to 1998. J Arid Environ 61(4):651–668. https://doi.org/10.1016/j.jaridenv.2004.10.001
Hoover DL, Rogers BM (2016) Not all droughts are created equal: the impacts of interannual drought pattern and magnitude on grassland carbon cycling. Glob Change Biol 22(5):1809–1820
Hoover D, Knapp AK, Smith MD (2014a) Contrasting sensitivities of two dominant C4 grasses to heat waves and drought. Plant Ecol 215:721–731.
Hoover DL, Knapp AK, Smith MD (2014b) Resistance and resilience of a grassland ecosystem to climate extremes. Ecology 95(9):2646–2656. https://doi.org/10.1890/13-2186.1
Hoover DL, Wilcox KR, Young KE (2018) Experimental droughts with rainout shelters: a methodological review. Ecosphere 9(1):e02088. https://doi.org/10.1002/ecs2.2088
IPCC (2021) Climate Change 2021: The physical science basis. contribution of working group I to the Sixth assessment report of the intergovernmental panel on climate change. Cambridge University Press
Isbell F, Craven D, Connolly J, Loreau M, Schmid B, Beierkuhnlein C, Bezemer TM, Bonin C, Bruelheide H, De Luca E, Ebeling A (2015) Biodiversity increases the resistance of ecosystem productivity to climate extremes. Nature 526(7574):574–577. https://doi.org/10.1038/nature15374
Jones MB (2019) Projected climate change and the global distribution of grasslands. Grasslands and Climate Change. Cambridge University Press, Cambridge, UK, pp 67–81
Keen R, Nippert J (2024) SRM01 ShRaMPs (Shrub Rainout Manipulation Plots): interactive effects of drought and fire on grass and shrub physiology and productivity at Konza Prairie. Environ Data Initiative. https://doi.org/10.6073/pasta/d77b1696b198e152e12b87e8e8996777
Keen RM, Nippert JB, Sullivan PL, Ratajczak Z, Ritchey B, O’Keefe K, Dodds WK (2022) Impacts of Riparian and Non-riparian woody encroachment on tallgrass Prairie Ecohydrology. Ecosystems. https://doi.org/10.1007/s10021-022-00756-7
Knapp AK (1984) Water relations and growth of three grasses during wet and drought years in a tallgrass prairie. Oecologia 65(1):35–43
Knapp AK (1985) Effect of fire and drought on the ecophysiology of Andropogon gerardii and Panicum virgatum in a tallgrass prairie. Ecology 66(4):1309–1320
Knapp AK, Medina E (1999) Success of C4 photosynthesis in the field: lessons from communities dominated by C4 plants. In: Sage RF, Monson RK (eds) C4 Plant Biology. Academic Press, San Diego, California, pp 251–283
Knapp AK, Briggs JM, Collins SL, Archer SR, Bret-Harte MS, Ewers BE, Peters DP, Young DR, Shaver GR, Pendall E, Cleary MB (2008) Shrub encroachment in North American grasslands: shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global Changes Biol 14(3):615–623. https://doi.org/10.1111/j.1365-2486.2007.01512.x
Knapp AK, Carroll CJ, Denton EM, La Pierre KJ, Collins SL, Smith MD (2015) Differential sensitivity to regionalscale drought in six central US grasslands. Oecologia 177:949–957
Kuznetsova A, Brockhoff PB, Christensen RH (2017) lmerTest package: tests in linear mixed effects models. J Stat Softw 82:1–26
Lenth R (2020) emmeans: estimated marginal means, aka least-squares means. R Package Version 1(5):4
Lett MS, Knapp AK, Briggs JM, Blair JM (2004) Influence of shrub encroachment on aboveground net primary productivity and carbon and nitrogen pools in a mesic grassland. Can J Botany 82(9):1363-1370
Liu F, Liu J, Doug M (2016) Ecological consequences of clonal integration in plants. Front Plant Sci 7:770. https://doi.org/10.3389/fpls.2016.00770
Logan KE, Brunsell NA (2015) Influence of drought on growing season carbon and water cycling with changing land cover. Agric for Meteorol 213:217–225. https://doi.org/10.1016/j.agrformet.2015.07.002
Luo W, Zuo X, Griffin-Nolan RJ, Xu C, Sardans J, Yu Q, Wang Z, Han X, Peñuelas J (2020) Chronic and intense droughts differentially influence grassland carbon-nutrient dynamics along a natural aridity gradient. Plant Soil. https://doi.org/10.1007/s11104-020-04571-8
McDowell NG (2011) Mechanisms linking drought, hydraulics, carbon metabolism, and vegetation mortality. Plant Physiol 155(3):1051–1059. https://doi.org/10.1111/j.1469-8137.2008.02436.x
McDowell N, Pockman WT, Allen CD, Breshears DD, Cobb N, Kolb T, Plaut J, Sperry J, West A, Williams DG, Yepez EA (2008) Mechanisms of plant survival and mortality during drought: why do some plants survive while others succumb to drought? New Phytol 178(4):719–739. https://doi.org/10.1111/j.1469-8137.2008.02436.x
Muench AT, O’Keefe K, Nippert JB (2016) Comparative ecohydrology between Cornus drummondii and Solidago canadensis in upland tallgrass prairie. Plant Ecol 217(3):267–276. https://doi.org/10.1007/s11258-016-0567-z
Mureva A, Ward D, Pillay T, Chivenge P, Cramer M (2018) Soil organic carbon in- creases in semi-arid regions while it decreases in humid regions due to woody–plant encroachment of grasslands in South Africa. Sci Rep 8(1):15506. https://doi.org/10.1038/s41598-018-33701-7
Nelson LR, Ezell AW, Yeiser JL (2006) Imazapyr and triclopyr tank mixtures for basal bark control of woody brush in the southeastern United States. New for 31(2):173–183. https://doi.org/10.1007/s11056-005-0925-5
Nippert JB (2023) APT01 Daily precipitation amounts measured at multiple sites across konza prairie. Environ Data Initiative. https://doi.org/10.6073/pasta/743c6b205e38a087bc54925ed258f549
Nippert JB, Knapp AK (2007) Linking water uptake with rooting patterns in grassland species. Oecologia 153(2):261–272. https://doi.org/10.1007/s00442-007-0745-8
Nippert JB, Fay PA, Knapp AK (2007) Photosynthetic traits in C3 and C4 grassland species in mesocosm and field environments. Environ Exp Bot 60:412–420. https://doi.org/10.1016/j.envexpbot.2006.12.012
Nippert JB, Fay PA, Carlisle JD, Knapp AK, Smith MD (2009) Ecophysiological responses of two dominant grasses to altered temperature and precipitation regimes. Acta Oecologica 35(3):400–408. https://doi.org/10.1016/j.actao.2009.01.010
Nippert JB, Wieme RA, Ocheltree TW, Craine JM (2012) Root characteristics of C4 grasses limit reliance on deep soil water in tallgrass prairie. Plant Soil 355(1):385–394. https://doi.org/10.1007/s11104-011-1112-4
Nippert JB, Ocheltree TW, Orozco GL, Ratajczak Z, Ling B, Skibbe AM (2013) Evidence of physiological decoupling from grassland ecosystem drivers by an encroaching woody shrub. PLoS ONE 8(12):e81630. https://doi.org/10.1371/journal.pone.0081630
Nippert JB, Telleria L, Blackmore P, Taylor JH, O’Connor RC (2021) Is a prescribed fire sufficient to slow the spread of woody plants in an infrequently burned grassland? A case study in tallgrass prairie. Rangel Ecol Manage 78:79–89. https://doi.org/10.1016/j.rama.2021.05.007
O’Connor RC, Taylor JH, Nippert JB (2020) Browsing and fire decreases dominance of a resprouting shrub in woody encroached grassland. Ecology 101(2):e02935. https://doi.org/10.1002/ecy.2935
O’Keefe K, Nippert JB (2017) Grazing by bison is a stronger driver of plant ecohydrology in tallgrass prairie than fire history. Plant Soil 411(1):423–436. https://doi.org/10.1007/s11104-016-3048-1
O’Keefe K, Bell DM, McCulloh KA, Nippert JB (2020) Bridging the flux gap: Sap flow measurements reveal species-specific patterns of water use in a tallgrass prairie. J Geophys Res. https://doi.org/10.1029/2019JG005446
Ott JP, Klimešová J, Hartnett DC (2019) The ecology and significance of below-ground bud banks in plants. Ann Bot 123:1099–1118. https://doi.org/10.1093/aob/mcz051
R Core Team (2021) R: a language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing
Ransom MD, Rice CW, Todd TC, Wehmueller WA (1998) Soils and soil biota. In: Knapp AK, Briggs JM, Hartnett DC, Collins SL (eds) Grassland Dynamics—Long-Term Ecological Research in Tallgrass Prairie. Oxford University Press, New York, pp 48–66
Ratajczak Z, Nippert JB, Hartman JC, Ocheltree TW (2011) Positive feedbacks amplify rates of woody encroachment in mesic tallgrass prairie. Ecosphere 2:art121. https://doi.org/10.1890/ES11-00212.1
Ratajczak Z, Nippert JB, Collins SL (2012) Woody encroachment decreases diversity across North American grasslands and savannas. Ecology 93(4):697–703. https://doi.org/10.1890/11-1199.1
Ratajczak Z, Nippert JB, Briggs JM, Blair JM (2014a) Fire dynamics distinguish grasslands, shrublands and woodlands as alternative attractors in the Central Great Plains of North America. J Ecol 102(6):1374–1385. https://doi.org/10.1111/1365-2745.12311
Ratajczak Z, Nippert JB, Ocheltree TW (2014b) Abrupt transition of mesic grass- land to shrubland: evidence for thresholds, alternative attractors, and regime shifts. Ecology 95(9):2633–2645. https://doi.org/10.1890/13-1369.1
Ratajczak Z, Briggs JM, Goodin DG, Luo L, Mohler RL, Nippert JB, Obermeyer B (2016) Assessing the potential for transitions from tallgrass prairie to woodlands: are we operating beyond critical fire thresholds? Rangel Ecol Manage 69(4):280–287. https://doi.org/10.1016/j.rama.2016.03.004
Reichma OJ (1987) Konza Prairie: a tallgrass natural history. University Press of Kansas, Lawrence, Kansas
Rodriguez-Dominguez CM, Forner A, Martorell S, Choat B, Lopez R, Peters JM, Pfautsch S, Mayr S, Carins-Murphy MR, McA SA, Richardson F (2022) Leaf water potential measurements using the pressure chamber: Synthetic testing of assumptions towards best practices for precision and accuracy. Plant Cell Environ 45(7):2037–2061. https://doi.org/10.1111/pce.14330
Slette IJ, Hoover DL, Smith MD, Knapp AK (2022) Repeated extreme droughts decrease root production, but not the potential for post-drought recovery of root production, in a mesic grassland. Oikos. https://doi.org/10.1111/oik.08899
Stambaugh MC, Guyette RP, Marschall J (2013) Fire history in the Cherokee Nation of Oklahoma. Hum Ecol 41:749–758. https://doi.org/10.1007/s10745-013-9571-2
Stevens N, Lehmann CE, Murphy BP, Durigan G (2017) Savanna woody encroachment is widespread across three continents. Global Changes Biol 23(1):235–244. https://doi.org/10.1111/gcb.13409
Strydom T, Smit IPJ, Govender N, Coetsee C, Singh J, Davies AB, van Wilgen BW (2023) High-intensity fires may have limited medium-term effectiveness for reversing woody plant encroachment in an African savanna. J Appl Ecol 60:661–672. https://doi.org/10.1111/1365-2664.14362
Sullivan PL, Zhang C, Behm M, Zhang F, Macpherson GL (2020) Toward a new conceptual model for groundwater flow in merokarst systems: Insights from multiple geophysical approaches. Hydrol Process 34(24):4697–4711. https://doi.org/10.1002/hyp.13898
Tooley EG, Nippert JB, Bachle S, Keen RM (2022) Intra-canopy leaf trait variation facilitates high leaf area index and compensatory growth in a clonal woody encroaching shrub. Tree Physiol 42(11):2186–2202. https://doi.org/10.1093/treephys/tpac078
Twidwell D, Rogers WE, Fuhlendorf SD, Wonkka CL, Engle DM, Weir JR, Kreuter UP, Taylor CA Jr (2013) The rising Great Plains fire campaign: citizens’ response to woody plant encroachment. Front Ecol Environ 11(s1):e64–e71. https://doi.org/10.1890/130015
Twidwell D, Rogers WE, Wonkka CL, Taylor CA Jr, Kreuter UP (2016) Extreme prescribed fire during drought reduces survival and density of woody resprouters. J Appl Ecol 53(5):1585–1596. https://doi.org/10.1111/1365-2664.12674
Van Auken OW (2000) Shrub invasions of North American semiarid grasslands. Ann Rev Ecol System 31(1):197–215. https://doi.org/10.1146/annurev.ecolsys.31.1.197
Vero SE, Macpherson GL, Sullivan PL, Brookfield AE, Nippert JB, Kirk MF, Datta S, Kempton P (2017) Developing a conceptual framework of landscape and hydrology on Tallgrass Prairie: a critical zone approach. Vadose Zone J 17(1):1–11. https://doi.org/10.2136/vzj2017.03.0069
Viglizzo EF, Nosetto MD, Jobbágy EG, Ricard MF, Frank FC (2015) The ecohydrology of ecosystem transitions: A meta-analysis. Ecohydrology 8(5):911–921. https://doi.org/10.1002/eco.1540
Wedel ER, O’Keefe K, Nippert JB, Hoch B, O’Connor RC (2021a) Spatio-temporal differences in leaf physiology are associated with fire, not drought, in a clonally integrated shrub. AoB Plants 13(4):plab037. https://doi.org/10.1093/aobpla/plab037
Wedel ER, Nippert JB, Hartnett DC (2021b) Fire and browsing interact to alter intra-clonal stem dynamics of an encroaching shrub in tallgrass prairie. Oecologia 196(4):1039–1048. https://doi.org/10.1007/s00442-021-04980-1
Wehner MF, Arnold JR, Knutson T, Kunkel KE, LeGrande AN (2017) Droughts, floods, and wildfires. In: Wuebbles DJ, Fahey DW, Hibbard KA, Dokken DJ, Stewart BC, Maycock TK (eds) Climate science special report: fourth national climate assessment, vol I. US Global Change Research Program, Washington, pp 231–256
Wilcox KR, Koerner SE, Hoover DL, Borkenhagen AK, Burkepile DE, Collins SL, Hoffman AM, Kirkman KP, Knapp AK, Strydom T, Thompson DI (2020) Rapid recovery of ecosystem function following extreme drought in a South African savanna grassland. Ecology 101(4):e02983. https://doi.org/10.1002/ecy.2983
Zou CB, Twidwell D, Bielski CH, Fogarty DT, Mittelstet AR, Starks PJ, Will RE, Zhong Y, Acharya BS (2018) Impact of eastern redcedar proliferation on water resources in the Great Plains USA –current state of knowledge. Water 10(12):1768. https://doi.org/10.3390/w10121768
Acknowledgements
The authors would like to thank the site management and staff at the Konza Prairie Biological Station for maintenance of fire treatments and access to ShRaMPs. In particular, the authors would like to thank Patrick O’Neal and Jim Larkins for organizing and leading prescribed burns each year, as well as the many volunteers for helping on burn crews. The authors would like to thank Mark Sandwick and Micke Ramirez for assisting with ShRaMPs site maintenance, as well as the LTER undergraduate students for helping remove and re-apply shelter roofs. The authors also thank Jeff Taylor who measured species composition each year from 2017 to 2022. Substantial help with fieldwork was provided by Emily Wedel and Greg Tooley throughout the project, for which we are very grateful. The authors also thank the undergraduate lab technicians (Lauren Gill, Sarah Schaffer, and Meghan Maine) in the EcoPhys lab for assisting with field- and lab-work associated with ShRaMPs. Funding for this project was provided by the U.S. Department of Energy (DOE-BER Program; DE-SC0019037) and the Long-Term Ecological Research (LTER) program (NSF 1440484).
Funding
Funding for this project was provided by the U.S. Department of Energy (DOE-BER Program; DE-SC0019037) and the Long-Term Ecological Research (LTER) program (NSF 1440484).
Author information
Authors and Affiliations
Contributions
JBN established the experimental design at ShRaMPs. Data collection was led by RMK, with assistance from JBN and SB. MB developed the allometric equations necessary to estimate shrub biomass. Data analysis and writing were led by RMK, with substantial input from JBN, SB, and MB. All authors critically examined and edited the manuscript and gave final approval before publication.
Corresponding author
Ethics declarations
Conflict of interest
The author declare that they have no conflict of interest.
Ethics approval
Not applicable.
Consent to participate
Not applicable.
Consent for publication
Not applicable.
Additional information
Communicated by Melinda D. Smith.
Supplementary Information
Below is the link to the electronic supplementary material.
Appendix 1
Appendix 1
Combined effects of fire and drought are not sufficient to slow shrub encroachment in tallgrass prairie.
Cornus drummondii Allometric Equations
Allometric equations were developed to estimate C. drummondii aboveground biomass based on stem counts and measurement of basal stem diameters. This method is non-destructive and prevents the removal of perennial aboveground shrub biomass, allowing for the measurement of year-to-year changes in shrub biomass. A previous study by Lett et al. (2004) developed similar equations for C. drummondii in northeastern Kansas and found strong relationships between stem basal area and both leaf and woody biomass. These additional equations were developed (by M. Bartmess) to span a wider range of stem diameters than those included in Lett et al. 2004, making them appropriate to use in larger, well-established C. drummondii shrub islands (Figs.
Allometric regression for the natural log of C. drummondii total biomass (leaves + stems) and the natural log of C. drummondii basal stem diameter
7,
Allometric regression for the natural log of C. drummondii woody biomass (stems) and the natural log of C. drummondii basal stem diameter
8,
Allometric regression for the natural log of C. drummondii leaf biomass and the natural log of C. drummondii basal stem diameter
9).
To develop these allometric equations, C. drummondii stems were collected in July of 2019 (the estimated time of peak foliar biomass for C. drummondii). A total of 62 stems with a range of 1–55 mm basal diameter were harvested near ground-level using bypass pruners and a pruning saw. All individual stems were then labelled, basal diameter was measured at each cut end, and leaves were removed. Leaves and stems were dried at 60 °C for roughly five days, or until the mass of each sample stabilized between measurements. The mass of each stem and associated leaf biomass was weighed after drying was complete. Least-squares regressions were performed for total biomass (leaves + stems), leaves only, and stems only. In all models, ln(mass) (where ‘mass’ is the mass of stems, leaves, or stems + leaves) was included as the response variable and ln(basal stem diameter) was included as the independent variable. The natural log transformation was selected based on the curve shape of the linear plotted data. Developed equations for total biomass (leaves + stems; Fig. 1), leaves only (Fig. 2), and stems only (Fig. 3) can be found below.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Keen, R.M., Bachle, S., Bartmess, M. et al. Combined effects of fire and drought are not sufficient to slow shrub encroachment in tallgrass prairie. Oecologia (2024). https://doi.org/10.1007/s00442-024-05526-x
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00442-024-05526-x