Cooperative Institute for Research in Environmental Sciences

Carol A. Wessman

Carol A. Wessman

Research Interests

Ecosystem ecology, landscape ecology, regional and global biogeochemical cycling, ecological applications of remote sensing and geographic information systems. Current research includes studies of ecosystem controls over biophysical fluxes (CO2, water and energy) within global grasslands and semiarid lands utilizing remotely sensed spectral data in conjunction with simulation models; scaling site-level ecology to landscape and regional scales in the alpine; quantitative methods that link spatial patterns and ecological processes at broad spatial and temporal scales.


Current Research

Multiple forest disturbances, their interactions, and cumulative effects on carbon dynamics in forest ecosystems

Disturbances have a strong role in the carbon balance of many ecosystems, and the cycle of vegetation growth, disturbance, and recovery is very important in determining the net carbon balance of terrestrial biomes. Despite potentially large losses of carbon in disturbance events (due to combustion, decomposition, or other mechanisms), resilient systems can recover that balance to remain neutral over the disturbance return interval. Conversely, lack of recovery may initiate alternate regimes with a different carbon balance. Compound disturbances are phenomena of growing concern and can further impact ecosystems in novel ways, altering disturbance intensity, severity, and recovery trajectories.

This research focuses on carbon stocks in a compound disturbance environment, with special attention on black carbon (charcoal). Black carbon is a potential source of long-term carbon sequestration, as it is very resistant to decomposition, formed in fires, and has numerous other benefits such as increasing soil fertility. We extensively surveyed a compound disturbance event (wind, logging, and fire) in a Colorado subalpine forest for impacts on carbon stocks, black carbon, and regeneration. We considered all major pools, including organic and mineral soil, and contrasted them with neighboring undisturbed forests as a reference.

The disturbances had an additive effect on carbon loss, with increasing numbers of disturbances resulting in progressively decreasing carbon/black carbon stocks. We interpret this as resulting from substrate availability and fire intensity, and there was no significant difference between unburned and burned plots in terms of total black carbon. Given literature-derived decay rates, it appears that high-intensity fires may actually reduce net black carbon in these forests over the entire fire return interval, with additional disturbances compounding the loss.

Overall, high-intensity disturbances remove a large amount of carbon, and multiple disturbances compound this effect. Differences in regeneration have a small but significant difference on current carbon stocks, a difference that likely will get larger as time progresses due to differential species characteristics. Disturbances, and their interactions, will have long-lasting legacies for carbon, black carbon, and ecosystem structure and function.

 

View Publications

  • Beals, SC, DL Preston, CA Wessman and TR Seastedt (2015), Resilience of a novel ecosystem after the loss of a keystone species: plague epizootics and urban prairie dog management. Ecosphere Version: 1 6 (9) , Art. No. 157, issn: 2150-8925, ids: CS5MF, doi: 10.1890/ES15-00244.1
  • Gartner, MH, TT Veblen, S Leyk and CA Wessman (2015), Detection of mountain pine beetle-killed ponderosa pine in a heterogeneous landscape using high-resolution aerial imagery. Int. J. Remote Sens. Version: 1 36 (21) 5353-5372, issn: 0143-1161, ids: CW6DA, doi: 10.1080/01431161.2015.1095369
  • Livneh, B, JS Deems, B Buma, JJ Barsugli, D Schneider, NP Molotch, K Wolter and CA Wessman (2015), Catchment response to bark beetle outbreak and dust-on-snow in the Colorado Rocky Mountains. J. Hydrol. Version: 1 523 196-210, issn: 0022-1694, ids: CE6TS, doi: 10.1016/j.jhydrol.2015.01.039
  • Buma, B, RE Poore and CA Wessman (2014), Disturbances, Their Interactions, and Cumulative Effects on Carbon and Charcoal Stocks in a Forested Ecosystem. Ecosystems Version: 1 17 (6) 947-959, issn: 1432-9840, ids: AN4JU, doi: 10.1007/s10021-014-9770-8
  • Buma, B and CA Wessman (2013), Forest resilience, climate change, and opportunities for adaptation: A specific case of a general problem. For. Ecol. Manage. Version: 1 306 216-225, issn: 0378-1127, ids: 228MI, doi: 10.1016/j.foreco.2013.06.044
  • Buma, B, ET Pugh and CA Wessman (2013), Effect of the current major insect outbreaks on decadal phenological and LAI trends in southern Rocky Mountain forests. Int. J. Remote Sens. Version: 1 34 (20) 7249-7274, issn: 0143-1161, ids: 196IL, doi: 10.1080/01431161.2013.817717
  • Madronich, MB, JP Greenberg, CA Wessman and AB Guenther (2012), Monoterpene emissions from an understory species, Pteridium aquilinum. Atmos. Environ. Version: 1 54 308-312, issn: 1352-2310, ids: 971JQ, doi: 10.1016/j.atmosenv.2012.02.047
  • Hinners, SJ, CA Kearns and CA Wessman (2012), Roles of scale, matrix, and native habitat in supporting a diverse suburban pollinator assemblage. Ecol. Appl. Version: 1 22 (7) 1923-1935, issn: 1051-0761, ids: 031GA, PubMed ID: 23210309
  • Buma, B and CA Wessman (2012), Differential species responses to compounded perturbations and implications for landscape heterogeneity and resilience. For. Ecol. Manage. Version: 1 266 25-33, issn: 0378-1127, ids: 898OM, doi: 10.1016/j.foreco.2011.10.040
  • Buma, B and CA Wessman (2011), Disturbance interactions can impact resilience mechanisms of forests. Ecosphere Version: 1 2 (5) , Art. No. UNSP 64, issn: 2150-8925, ids: V30IV, doi: 10.1890/ES11-00038.1
  • Golubiewski, NE and CA Wessman (2010), Discriminating urban vegetation from a metropolitan matrix through partial unmixing with hyperspectral AVIRIS data. Can. J. Remote Sens. Version: 1 36 (3) 261-275, issn: 1712-7971, ids: 681VZ
  • Kokaly, RF, GP Asner, SV Ollinger, ME Martin and CA Wessman (2009), Characterizing canopy biochemistry from imaging spectroscopy and its application to ecosystem studies. Remote Sens. Environ. Version: 1 Session on the State of Science of Environmental Applications of Imaging Spectroscopy held in honor of Alexander FH Goetz 113 S78-S91, Denver, CO, 2006, issn: 0034-4257, ids: 478CG, doi: 10.1016/j.rse.2008.10.018
  • Browning, DM, SR Archer, GP Asner, MP McClaran and CA Wessman (2008), Woody plants in grasslands: Post-encroachment stand dynamics. Ecol. Appl. Version: 1 18 (4) 928-944, issn: 1051-0761, ids: 306JD, doi: 10.1890/07-1559.1, PubMed ID: 18536253
  • Hughes, RF, SR Archer, GP Asner, CA Wessman, C McMurtry, J Nelson and RJ Ansley (2006), Changes in aboveground primary production and carbon and nitrogen pools accompanying woody plant encroachment in a temperate savanna. Glob. Change Biol. Version: 1 12 (9) 1733-1747, issn: 1354-1013, ids: 077CM, doi: 10.1111/J.1365-2486.2006.01210.x
  • Mangan, JM, JT Overpeck, RS Webb, C Wessman and AFH Goetz (2004), Response of Nebraska Sand Hills natural vegetation to drought, fire, grazing, and plant functional type shifts as simulated by the century model. Clim. Change Version: 1 63 (2-Jan) 49-90, issn: 0165-0009, ids: 800BZ, doi: 10.1023/B:CLIM.0000018516.53419.90
  • Hudak, AT, CA Wessman and TR Seastedt (2003), Woody overstorey effects on soil carbon and nitrogen pools in South African savanna. Austral Ecol. Version: 1 28 (2) 173-181, issn: 1442-9985, ids: 665HH, doi: 10.1046/j.1442-9993.2003.01265.x
  • Asner, GP, S Archer, RF Hughes, RJ Ansley and CA Wessman (2003), Net changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937-1999. Glob. Change Biol. Version: 1 9 (3) 316-335, issn: 1354-1013, ids: 652TX, doi: 10.1046/j.1365-2486.2003.00594.x
  • Hudak, AT and CA Wessman (2001), Textural analysis of high resolution imagery to quantify bush encroachment in Madikwe Game Reserve, South Africa, 1955-1996. Int. J. Remote Sens. Version: 1 22 (14) 2731-2740, issn: 0143-1161, ids: 473DC, doi: 10.1080/01431160119030
  • Bateson, CA, GP Asner and CA Wessman (2000), Endmember bundles: A new approach to incorporating endmember variability into spectral mixture analysis. IEEE T Geosci. Remote Version: 1 38 (2) 1083-1094, issn: 0196-2892, ids: 304TG, doi: 10.1109/36.841987
  • Asner, GP, CA Wessman, CA Bateson and JL Privette (2000), Impact of tissue, canopy, and landscape factors on the hyperspectral reflectance variability of arid ecosystems. Remote Sens. Environ. Version: 1 74 (1) 69-84, issn: 0034-4257, ids: 356NA, doi: 10.1016/S0034-4257(00)00124-3
  • Vierling, LA and CA Wessman (2000), Photosynthetically active radiation heterogeneity within a monodominant Congolese rain forest canopy. Agric. For. Meteorol. Version: 1 103 (3) 265-278, issn: 0168-1923, ids: 322VQ, doi: 10.1016/S0168-1923(00)00129-5
  • Asner, GP, CA Wessman, DS Schimel and S Archer (1998), Variability in leaf and litter optical properties: Implications for BRDF model inversions using AVHRR, MODIS, and MISR. Remote Sens. Environ. Version: 1 63 (3) 243-257, issn: 0034-4257, ids: YX797, doi: 10.1016/S0034-4257(97)00138-7
  • Asner, GP, BH Braswell, DS Schimel and CA Wessman (1998), Ecological research needs from multiangle remote sensing data. Remote Sens. Environ. Version: 1 63 (2) 155-165, issn: 0034-4257, ids: YM346, doi: 10.1016/S0034-4257(97)00139-9
  • Asner, GP, CA Wessman and S Archer (1998), Scale dependence of absorption of photosynthetically active radiation in terrestrial ecosystems. Ecol. Appl. Version: 1 8 (4) 1003-1021, issn: 1051-0761, ids: 141EL, doi: 10.1890/1051-0761(1998)008[1003:SDOAOP]2.0.CO;2
  • Asner, GP, CA Bateson, JL Privette, N El Saleous and CA Wessman (1998), Estimating vegetation structural effects on carbon uptake using satellite data fusion and inverse modeling. J. Geophys. Res.-Atmos. Version: 1 103 (D22) 28839-28853, issn: 2169-897X, ids: 142JB, doi: 10.1029/98JD02459
  • Asner, GP, CA Wessman and DS Schimel (1998), Heterogeneity of savanna canopy structure and function from imaging spectrometry and inverse modeling. Ecol. Appl. Version: 1 8 (4) 1022-1036, issn: 1051-0761, ids: 141EL
  • Hudak, AT and CA Wessman (1998), Textural analysis of historical aerial photography to characterize woody plant encroachment in South African savanna. Remote Sens. Environ. Version: 1 66 (3) 317-330, issn: 0034-4257, ids: 142CX, doi: 10.1016/S0034-4257(98)00078-9
  • Asner, GP, CA Wessman and JL Privette (1997), Unmixing the directional reflectances of AVHRR sub-pixel landcovers. IEEE Trans. Geosci. Remote Sensing Version: 1 1996 International Geoscience and Remote Sensing Symposium (IGARSS 96) - Remote Sensing for a Sustainable Future 35 (4) 868-878, LINCOLN, NE, MAY 21-31, 1996, issn: 0196-2892, ids: XL049, doi: 10.1109/36.602529
  • Wessman, CA, CA Bateson and TL Benning (1997), Detecting fire and grazing patterns in tallgrass prairie using spectral mixture analysis. Ecol. Appl. Version: 1 7 (2) 493-511, issn: 1051-0761, ids: WW233, doi: 10.2307/2269515
  • Asner, GP and CA Wessman (1997), Scaling PAR absorption from the leaf to landscape level in spatially heterogeneous ecosystems. Ecol. Model. Version: 1 103 (1) 81-97, issn: 0304-3800, ids: YE663, doi: 10.1016/S0304-3800(97)00080-X
  • NEL, EM, CA WESSMAN and TT VEBLEN (1994), DIGITAL AND VISUAL ANALYSIS OF THEMATIC MAPPER IMAGERY FOR DIFFERENTIATING OLD-GROWTH FROM YOUNGER SPRUCE-FIR STANDS. Remote Sens. Environ. Version: 1 48 (3) 291-301, issn: 0034-4257, ids: NV604, doi: 10.1016/0034-4257(94)90003-5
  • NEL, EM and CA WESSMAN (1993), CANOPY TRANSMITTANCE MODELS FOR ESTIMATING FOREST LEAF-AREA INDEX. Can. J. For. Res.-Rev. Can. Rech. For. Version: 1 23 (12) 2579-2586, issn: 0045-5067, ids: MV940, doi: 10.1139/x93-319
  • WALKER, DA, JC HALFPENNY, MD WALKER and CA WESSMAN (1993), LONG-TERM STUDIES OF SNOW-VEGETATION INTERACTIONS. Bioscience Version: 1 43 (5) 287-301, issn: Jun-68, ids: KX575, doi: 10.2307/1312061
  • WESSMAN, CA (1992), IMAGING SPECTROMETRY FOR REMOTE-SENSING OF ECOSYSTEM PROCESSES. Version: 1 REMOTE SENSING OF THE EARTHS SURFACE AND ATMOSPHERE 2ND SYMP AND THE TOPICAL MEETING OF THE INTERDISCIPLINARY SCIENTIFIC COMMISSION OF THE COSPAR 28TH PLENARY MEETING : REMOTE SENSING OF THE EARTHS SURFACE AND ATMOSPHERE2ND SYMP AND THE TOPICAL MEETING OF THE INTERDISCIPLINARY SCIENTIFIC COMMISSION OF THE 12 361-368, THE HAGUE, NETHERLANDSTHE HAGUE, NETHERLANDS, JUN 25-JUL 06, 1990JUN 25-JUL 06, 1990, Ed. SINGH, RP; TABBAGH, A; GOWER, JFR; SMITH, WL; MACDONALD, AE; MANTON, MJ; PAILLEUX, J; TSUCHIYA, K; DOZIER, J, isbn: 0-08-041853-8, doi: 10.1016/0273-1177(92)90241-O
  • WESSMAN, CA (1992), SPATIAL SCALES AND GLOBAL CHANGE - BRIDGING THE GAP FROM PLOTS TO GCM GRID CELLS. Annu. Rev. Ecol. Syst. Version: 1 23 175-200, issn: 0066-4162, ids: JZ281, doi: 10.1146/annurev.es.23.110192.001135
  • USTIN, SL, CA WESSMAN, B CURTISS, E KASISCHKE, J WAY and VC VANDERBILT (1991), OPPORTUNITIES FOR USING THE EOS IMAGING SPECTROMETERS AND SYNTHETIC APERTURE RADAR IN ECOLOGICAL MODELS. Ecology Version: 1 72 (6) 1934-1945, issn: Dec-58, ids: GV769
  • WESSMAN, CA (1991), REMOTE-SENSING OF SOIL PROCESSES. Agric. Ecosyst. Environ. Version: 1 34 (4-Jan) 479-493, issn: 0167-8809, ids: FD132, doi: 10.1016/0167-8809(91)90131-G
  • WESSMAN, CA, JD ABER and DL PETERSON (1989), AN EVALUATION OF IMAGING SPECTROMETRY FOR ESTIMATING FOREST CANOPY CHEMISTRY. Int. J. Remote Sens. Version: 1 10 (8) 1293-1316, issn: 0143-1161, ids: AN327
  • WESSMAN, CA, JD ABER, DL PETERSON and JM MELILLO (1988), FOLIAR ANALYSIS USING NEAR-INFRARED REFLECTANCE SPECTROSCOPY. Can. J. For. Res.-Rev. Can. Rech. For. Version: 1 18 (1) 6-11, issn: 0045-5067, ids: M5818
  • WESSMAN, CA, JD ABER, DL PETERSON and JM MELILLO (1988), REMOTE-SENSING OF CANOPY CHEMISTRY AND NITROGEN CYCLING IN TEMPERATE FOREST ECOSYSTEMS. Nature Version: 1 335 (6186) 154-156, issn: 0028-0836, ids: P9647, doi: 10.1038/335154a0
  • PETERSON, DL, JD ABER, PA MATSON, DH CARD, N SWANBERG, C WESSMAN and M SPANNER (1988), REMOTE-SENSING OF FOREST CANOPY AND LEAF BIOCHEMICAL CONTENTS. Remote Sens. Environ. Version: 1 24 (1) 85-&, issn: 0034-4257, ids: M2254, doi: 10.1016/0034-4257(88)90007-7