Forest dynamics following eastern hemlock mortality in the southern Appalachians

Oikos - Tập 121 Số 4 - Trang 523-536 - 2012
Chelcy R. Ford1, Katherine J. Elliott1, Barton D. Clinton1, Brian D. Kloeppel1, James M. Vose1
1USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory, Otto, NC 28763, USA

Tóm tắt

Understanding changes in community composition caused by invasive species is critical for predicting effects on ecosystem function, particularly when the invasive threatens a foundation species. Here we focus on dynamics of forest structure, composition and microclimate, and how these interact in southern Appalachian riparian forests following invasion by hemlock woolly adelgid, HWA, Adelges tsugae. We measured and quantified changes in microclimate; canopy mortality; canopy and shrub growth; understory species composition; and the cover and diversity in riparian forests dominated by eastern hemlock Tsuga canadensis over a period of seven years. Treatments manipulated hemlock mortality either through invasion (HWA infested stands) or girdling (GDL) hemlock trees.

Mortality was rapid, with 50% hemlock tree mortality occurring after six years of invasion, in contrast to more than 50% mortality in two years following girdling. Although 50% of hemlock trees were still alive five years after infestation, leaf area lost was similar to that of girdled trees. As such, overall responses over time (changes in light transmittance, growth, soil moisture) were identical to girdled stands with 100% mortality. Our results showed different growth responses of the canopy species, shrubs and ground layer, with the latter being substantially influenced by presence of the evergreen shrub, rhododendron Rhododendron maximum. Although ground layer richness in the infested and girdled stands increased by threefold, they did not approach levels recorded in hardwood forests without rhododendron. Increased growth of co‐occurring canopy trees occurred in the first few years following hemlock decline, with similar responses in both treatments. In contrast, growth of rhododendron continued to increase over time. By the end of the study it had a 2.6‐fold higher growth rate than expected, likely taking advantage of increased light available during leaf‐off periods of the deciduous species. Increased growth and dominance of rhododendron may be a major determinant of future responses in southern Appalachian ecosystems; however, our results suggest hemlock will be replaced by a mix of Acer, Betula, Fagus and Quercus canopy genera where establishment is not limited by rhododendron.

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Tài liệu tham khảo

10.1016/j.foreco.2009.09.001

10.2307/1939835

10.1038/nature05038

10.1016/S0378-1127(98)00259-X

10.1139/x00-075

10.1139/x01-199

Cattelino P. J., 1986, Construction and installation of homemade dendrometer bands, North. J. Appl. For., 3, 73, 10.1093/njaf/3.2.73

Clarke R, 1986, The handbook of ecological monitoring

10.1016/S0378-1127(03)00277-9

10.2307/2426587

10.1111/j.1600-0706.2009.18308.x

Costa S. D., 2008, 4th Symp. on Hemlock Woolly Adelgid in the eastern US, 47

10.1890/070151

10.1146/annurev.ecolsys.34.011802.132403

10.1139/X07-045

10.1016/j.foreco.2005.02.064

10.1007/s11258-007-9352-3

10.1016/j.foreco.2010.03.010

10.2307/2997316

10.1007/978-94-007-1620-9_7

Ellison A. M., 2005, Loss of foundation species: consequences for the structure and dynamics of forested ecosystems, Front. Ecol. Environ., 9, 479, 10.1890/1540-9295(2005)003[0479:LOFSCF]2.0.CO;2

10.1126/science.285.5435.1834

10.1139/x06-050

10.1007/s00442-010-1697-y

10.1890/06-0027

10.2307/1940468

10.1890/0012-9658(2006)87[2959:ACDFAM]2.0.CO;2

Fritts H. C, 1976, Tree rings and climate

10.21135/893273651.001

10.1890/1051-0761(1998)008[0975:EOINIP]2.0.CO;2

10.1093/treephys/22.15-16.1079

10.1111/j.1600-0587.2009.05838.x

10.1139/x03-001

10.1111/j.1365-2664.2008.01600.x

10.1890/06-1097

Johnson E. A., 1956, Effect on streamflow of cutting a forest understory, For. Sci., 2, 82

10.1007/s10530-008-9318-y

10.3159/07-RA-018.1

10.1007/s11258-008-9431-0

10.1046/j.1365-2699.2002.00766.x

10.1111/j.1365-2486.2007.01512.x

Laseter S. H., Long‐term temperature and precipitation trends at the Coweeta Hydrologic Laboratory, Otto, North Carolina, USA, Hydrol. Res.

10.1111/j.1654-1103.2003.tb02175.x

10.1093/treephys/28.4.629

Little R. C., 1996, SAS system for mixed models

10.1641/0006-3568(2006)056[0395:FERTEP]2.0.CO;2

10.1007/s10021-010-9381-y

Magurran A. E, 2004, Measuring biological diversity

Manion P. D, 1981, Tree disease concepts

10.1093/aesa/82.1.50

McGee C. E., 1967, Undisturbed rhododendron thickets are not spreading, J. For., 65, 334

10.2179/08-049.1

Norris M. D., 2001, Land cover change in eastern Kansas: litter dynamics of closed‐canopy eastern redcedar forests in tallgrass prairie, Can. J. Bot., 79, 214

10.1007/s10021-008-9215-3

10.2307/2997232

10.1046/j.1365-2699.2002.00765.x

10.1890/1540-9295(2004)002[0131:BBWAAO]2.0.CO;2

Parker B. L., 1998, Survival of hemlock woolly adelgid (Homoptera : Adelgidae) at low temperatures, For. Sci., 44, 414

10.1093/ee/28.6.1085

10.2307/2996120

10.1007/s00267-009-9317-5

10.1111/j.1365-2435.2008.01534.x

10.1603/0046-225X-32.3.523

10.3159/1095-5674(2005)132[458:CIAHFF]2.0.CO;2

10.1007/s10530-010-9704-0

10.1007/s10021-003-0092-5

10.1890/0012-9658(2006)87[1792:TEOEAN]2.0.CO;2

10.3159/1095-5674(2006)133[393:TSBOHF]2.0.CO;2

10.1007/978-1-4612-3732-7_3

10.1603/022.038.0309

10.2307/1310667

10.1146/annurev.ecolsys.35.021103.105708

10.1016/j.pedobi.2006.10.001

10.1111/j.1365-2745.2009.01487.x

10.1139/x03-073

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Oikos

Tập 121 Số 4

523-536

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