Coweeta (CWT)

Coweeta (CWT)

1992 – present

Coweeta has been a USFS Experimental Forest since 1934.  In recent decades it has hosted the Coweeta LTER.  Long-term demographic studies began in 1992, including seed traps, and sampling continues to the present.  Logistics at the site have been facilitated by Jim Vose, Chelcy Miniat, and Jason Love.  PhD theses using the long-term demographic data include those of Brian Beckage, Dave Bell, Mike Dietze, Janneke HilleRisLambers, Ines Ibanez, Emily Moran, and Mike Wolosin.

The watershed extends from Piedmont forests to northern hardwoods at the highest elevations.  Moisture gradients span xeric Pinus rigida stands to riparian forest.  Long-term demography began with the installation of “gradient” plots (CWT118, …, CWT527) in 1992, to be followed by experimental “gap” plots in 2000.  Seedling experiments (Beckage, Ibanez) and microsatellite studies (Moran) were conducted on gap sites.

Monthly effective precipitation over the last five years (left) and annual values since 1960 (right). At left are shown winter surpluses in blue and summer deficits in orange. At right are annual anomalies in minimum winter temperature and annual deficit.
CWT118
tree_years seed_count
amelArbo 832 0
amelUNKN 0 26
betuAlle 0 2
betuLent 156 283
betuUNKN 0 1586
caryOvalGlab 1482 0
caryTome 52 0
caryUNKN 0 78
cornFlor 1222 81
faguGran 312 0
liriTuli 338 0
magnAcum 182 0
magnFras 1430 0
magnUNKN 0 2
nyssSylv 2756 0
oxydArbo 1742 0
pinuRigi 936 246
pinuStro 78 0
pinuUNKN 0 224
querAlba 390 58
querCocc 1222 0
querFalc 0 41
querMari 104 0
querPrin 2470 7
querRubr 390 23
querUNKN 0 612
querVelu 1326 81
robiPseu 364 0
sassAlbi 2496 0
tsugCana 208 0

The following sites occupy control watershed 18, the Grady Branch Watershed, which has been undisturbed since 1927:

CWT-118 is a xeric ridge supporting mature Pinus rigida dating to past fire, with a dense understory of Quercus spp. and Kalmia latifolia.   Part of plot was destroyed by establishment of a landing for a logging operation, but most remains intact.

CWT218
tree_years seed_count
amelArbo 78 0
amelUNKN 0 10
betuAlle 26 142
betuLent 1040 5774
betuUNKN 0 35703
caryOvalGlab 910 0
caryUNKN 0 126
cornFlor 2002 16
faguGran 26 0
ilexMont 26 0
ilexUNKN 0 4
liriTuli 1872 0
magnAcum 52 0
magnFras 2132 0
magnUNKN 0 3
nyssSylv 572 0
oxydArbo 1248 0
pinuRigi 0 7
pinuStro 754 0
pinuUNKN 0 9
querAlba 0 9
querCocc 182 0
querFalc 0 29
querPrin 962 65
querRubr 104 14
querUNKN 0 186
querVelu 182 18
robiPseu 130 0
sassAlbi 156 0
tiliAmer 182 2024
tsugCana 780 0

CWT-218 is a sheltered cove site, dominated by Quercus spp., Liriodendron, Fraxinus, and Betula lenta.  This mesic forest has some recruitment of Pinus strobus in the understory.

The genus Acer at CWT-LG. Symbols proportional to tree diameter.
CWT318
tree_years seed_count
amelArbo 260 0
betuAlle 26 4
betuLent 338 1907
betuUNKN 0 15964
caryOvalGlab 1196 0
caryUNKN 0 257
cornFlor 702 2
fraxAmer 26 3
liriTuli 312 0
magnAcum 26 0
magnUNKN 0 26
nyssSylv 2808 0
oxydArbo 2054 0
querAlba 0 26
querCocc 26 0
querFalc 0 31
querPrin 2730 111
querRubr 546 46
querUNKN 0 163
querVelu 156 6
robiPseu 78 0
sassAlbi 52 0
tsugCana 234 0

CWT-318 is a mixed hardwood stand, with a dense Rhododendron understory on steep terrain.  It is dominated by Quercus spp. and includes Nyssa sylvatica.

The following sites occupy control watershed 27, the Hard Luck Creek Watershed. This has been a control watershed at least since 1946.

CWT427
tree_years seed_count
amelArbo 130 0
amelUNKN 0 3
betuAlle 0 12
betuLent 104 778
betuUNKN 0 3858
caryOvalGlab 442 0
caryUNKN 0 34
cornFlor 260 5
fraxAmer 52 4
ilexMont 260 3
ilexUNKN 0 4
liriTuli 260 0
magnAcum 26 0
magnFras 650 0
magnUNKN 0 8
nyssSylv 3380 0
oxydArbo 2522 0
querAlba 0 116
querCocc 390 0
querFalc 0 97
querPrin 2782 183
querRubr 1196 137
querUNKN 0 1641
querVelu 260 72
robiPseu 260 0
sassAlbi 234 0
tsugCana 2028 0

CWT-427 occupies a higher elevation, also on a slope.  It is contiguous with CWT-UG, which was installed later and includes experimental gaps.

CWT527
tree_years seed_count
amelArbo 494 0
amelUNKN 0 17
betuAlle 4680 3155
betuLent 1534 59108
betuUNKN 0 443573
caryOvalGlab 52 0
caryUNKN 0 15
cornFlor 130 1
faguGran 780 0
fraxAmer 1742 5432
ilexMont 3822 0
ilexUNKN 0 6
magnAcum 52 0
magnUNKN 0 2
oxydArbo 26 0
prunSero 26 0
querAlba 26 18
querFalc 0 173
querPrin 0 2
querRubr 598 300
querUNKN 0 1697
querVelu 26 0
tiliAmer 3432 1355
tsugCana 78 0

CWT-527 is a northern hardwoods stand, dominated by Acer saccharum and Betula alleghaniensis.

These sites occupy watershed 28, which accommodates manipulative experiments:

CWT-LG occupies a hill slope dominated by Quercus spp., Liriodendron, Nyssa sylvatica, and Acer rubrum.  It includes experimental gaps, 30 m in diameter, installed in 2000.

CWTLG
tree_years seed_count
amelArbo 1377 0
amelUNKN 0 6
betuAlle 187 20
betuLent 1921 1565
betuUNKN 0 4203
caryOvalGlab 3213 0
caryTome 1224 0
caryUNKN 952 64
cornAlte 68 0
cornFlor 2244 5
faguGran 255 0
fraxAmer 1819 5
ilexMont 187 0
ilexUNKN 0 8
liriTuli 23103 0
magnAcum 1955 0
magnFras 5491 0
magnUNKN 0 2
nyssSylv 5746 0
oxydArbo 2975 0
prunSero 102 0
prunUNKN 51 0
querAlba 51 66
querCocc 765 17
querFalc 0 51
querPrin 3927 65
querRubr 17238 209
querUNKN 0 480
querVelu 2516 23
robiPseu 1564 0
sassAlbi 1394 0
tiliAmer 34 54
tiliHete 306 0
tsugCana 4352 0
ulmuAlat 0 1
ulmuAmer 17 0

CWT-UG, contiguous with CWT-427, is dominated by Quercus spp., Nyssa sylvatica, ….  It includes canopy gaps installed in 2000.

CWTUG
tree_years seed_count
amelArbo 1955 0
amelUNKN 0 727
betuAlle 17 84
betuLent 1938 652
betuUNKN 0 5175
caryOvalGlab 204 0
caryTome 68 0
caryUNKN 68 14
cornAlte 17 0
cornFlor 153 5
ilexMont 1547 0
ilexUNKN 0 32
liquStyr 17 0
liriTuli 374 0
magnAcum 153 0
magnFras 510 0
nyssSylv 6579 0
oxydArbo 3536 0
pinuTaed 68 0
pinuUNKN 0 18
prunPens 68 0
prunUNKN 0 44
querAlba 0 23
querCocc 1309 0
querFalc 0 58
querPrin 3332 43
querRubr 1377 84
querUNKN 0 360
querVelu 272 42
robiPseu 714 0
sassAlbi 612 0
tsugCana 663 0
Mast and non-mast year for Acer at CWT-LG.

Climate data were obtained from stations along the LTER elevation gradient, the main CWT climate station, supplemented by precipitation data from the USFS.

Mast data are described in publications, including:

  • Berdanier, A. and J.S. Clark. 2016. Divergent reproductive allocation trade-offs with canopy exposure across tree species in temperate forests. Ecosphere, DOI:10.1002/ecs2.1313.
  • Bell, D.M. and J.S. Clark 2015. Seed predation and climate impacts on reproductive variation in temperate forests of the southeastern USA. Oecologia, 180, 1223–1234bell2016
  • Clark, J.S., D.M. Bell, M.C. Kwit, and K. Zhu. 2014. Competition-interaction landscapes for the joint response of forests to climate change. Global Change Biology, 20, 1979-1991.
  • Clark, J.S., D. Bell, C. Chu, B. Courbaud, M. Dietze, M. Hersh, J. HilleRisLambers, I. Ibanez, S. L. LaDeau, S. M. McMahon, C.J.E. Metcalf, J. Mohan, E. Moran, L. Pangle, S. Pearson, C. Salk, Z. Shen, D. Valle, and P. Wyckoff. 2010. High dimensional coexistence based on individual variation: a synthesis of evidence. EM2010, 80, 569–608. EM2010appendix-A, EM2010appendix-B
  • Clark, J.S. 2010. Individuals and the variation needed for high species diversity. Science 327, 1129-1132, science2010. scienceAppend2010
  • Clark, J.S., S. LaDeau, and I. Ibanez. 2004. Fecundity of trees and the colonization-competition hypothesis, Ecological Monographs, 74:415-442Appendix.
  • Hille Ris Lambers, J. and J.S. Clark. 2003. Effects of dispersal, shrubs, and density-dependent mortality on seed and seedling distributions in temperate forests. Canadian Journal of Forest Research 33: 783-795.
  • Clark, J.S., M. Silman, R. Kern, E. Macklin, and J. Hille Ris Lambers. 1999. Seed dispersal near and far: generalized patterns across temperate and tropical forests.  Ecology 80:1475-1494.
  • Clark, J. S., E. Macklin, and L. Wood.  1998. Stages and spatial scales of recruitment limitation in southern Appalachian forests.  Ecological Monographs 68:213-235.