After the success of the Communist revolution in 1949, China closed its boundaries to Westerners, ending collaboration between Chinese and American botanists until the 1970s. With the invitation in 1978 to a delegation of American botanists to visit the People’s Republic of China, ties broken three decades earlier were renewed. After the month-long visit, the Americans in turn invited their Chinese colleagues to visit the United States the next year. During that visit plans were made for a collaborative expedition to western Hubei Province the 1980 Sino-American Botanical Expedition—conducted under the auspices of Academia Sinica and the Botanical Society of America.*
As members of that expedition, the authors of this report did fieldwork in western Hubei Province in the late summer and early fall of 1980. Most of their time was spent in the Shennongjia Forest District, but they also made a brief visit, October 5 to 10, to the region where Metasequoia still grows wild, the first foreigners to visit since 1948.
After a visit to Modaoqi to see the tree that was the source of the type specimen of Metasequoia glyptostroboides, they continued on to Lichuan. For the next three days, they traveled to Metasequoia Valley, three hours each way. They sought out noteworthy trees of M. glyptostroboides and interviewed local officials about their work in inventorying and conserving the naturally occurring trees and about their program of seed collection and propagation. This excerpt relates their observations of the condition of wild-growing Metasequoia and of the vegetation associated with it.
Almost all of the naturally occurring trees of Metasequoia grow in the central valley of Xiaohe Commune. Since 1974 the Bureau of Forestry of Lichuan Xian [county] has maintained a staff of five people in the Commune, with one of their objectives being to measure each tree every four years. The Forest Bureau has counted and numbered 5,420 trees with a diameter (at breast height) of at least 20 centimeters [8 inches]. We were told that approximately 1,700 to 1,800 of these are mature, seed-producing trees. The tallest recorded trees in the valley are on the east side in the vicinity of Hongshaxi: several reach a height of about 50 meters [165 feet]. . . .
In its natural habitat Metasequoia is now protected by the government, and not even small trees may be cut. The trees that we saw (including the two ancient ones at Modaoqi and Xiaohe) all appeared to be in good health. However, we did not see any small seedlings. This differs from the situation in 1948, when Chu and Cooper found seedlings in thickets surrounding older Metasequoia trees. In 1980 vegetation was either absent around the trees of Metasequoia, or very closely cropped, presumably by the local people and not by animals. The lack of governmental protection of the habitat (and thus the lack of associated vegetation) probably accounts for the lack of seedling establishment.
The “Metasequoia Flora”
The habitat of Metasequoia is reminiscent of that of Taxodium distichum in the southeastern United States, a parallel previously drawn by Chaney. Metasequoia is a riparian species, and before habitation the valley floor may well have been a Metasequoia forest. Metasequoia trees that occur away from the valley floor are restricted to the moist bottoms of ravines and draws that drain into the main valley. Taxodium commonly occurs in flat, poorly drained depressions behind natural levees along slow-moving rivers. Based on this similarity of habitats, on reports of the species associated with Metasequoia (Chaney, Chu & Cooper, Gressitt), on [Shuiying] Hu’s enumeration of the “Metasequoia Flora,” and on our own observations, both in the southeastern United States and in the Metasequoia Valley in 1980, it is possible to hypothesize a past Metasequoia forest analogous to present-day Taxodium distichum forests.
Among the dominant tree species usually found with Taxodium distichum are Nyssa aquatica, N. sylvatica var. biflora, Populus heterophylla, Quercus spp., Liquidambar styraciflua, Carpinus caroliniana, Betula nigra, Acer rubrum, Ulmus americana, Carya spp., Fraxinus spp., and Salix spp. The associated shrubs include Ilex spp.. Viburnum spp., Itea virginica, Cornus spp., and Lindera benzoin. . . . While each of the species of this group has specific microhabitat requirements, all are usually found growing in close proximity to Taxodium.
In their list of plants growing with Metasequoia, Chu and Cooper included species of many of the same genera. We noted several large trees of Liquidambar acalycina and species of Salix, Acer, Pterocarya, and Quercus in habitats similar to those occupied by Metasequoia, but not on the adjacent slopes. Moreover, it seems likely that at one time the floor of the Metasequoia Valley was occupied by trees that were tolerant of periodic flooding, could grow in poorly drained soils, and occupied more or less specific microhabitats. Among the species listed as being associated with Metasequoia glyptostroboides by Chu and Cooper, Gressitt, and Hu, the following grow in habitats similar to those of their American counterparts associated with Taxodium: Houttuynia cordata (in place of Saururus cernuus in the southeastern United States); Populus adenopoda; Salix spp.; Pterocarya hupehensis; P. paliurus and P. stenoptera (all in place of Carya spp.); Betula luminifera; Carpinus fargesii; Quercus spp.; Morus sp.; Cocculus orbiculatus; Ulmus multinervis; Lindera glauca; Liquidambar acalycina (L. formosana in Chu and Cooper); Ilex spp.; Berchemia spp.; Nyssa sinensis; Cornus controversa and C. macrophylla; Clethra fargesii; Styrax bodinieri and S. suberifolius; Viburnum spp.; and Smilax spp. . . .
Chu and Cooper stated that Metasequoia appears to grow naturally only in sandy soil derived from Jurassic sandstone, and that only cultivated trees grow over limestone. They also mentioned that the valley floor is derived mainly from sandstone, providing rather strong suggestive evidence that the floor could have been occupied — and perhaps dominated—by much more extensive stands of Metasequoia. Additional evidence of a once more widespread Metasequoia forest on the valley floor is provided by several large trunks of Metasequoia that we saw that had recently been unearthed in the center of paddy fields far from the nearest slopes and ravines where the trees now grow. Altogether more than 200 of these trunks, many over two meters [6 1/2 feet] in diameter, have been found in the paddies along the level floodplain of the main river and side streams (T. S. Ying, pers. comm.). Also (according to Liu et ah), some of the houses in the valley were constructed of boards cut from Metasequoia. These houses are believed to be 200 to 300 years old and date roughly from the time of the original settlers. . . .
The high population density [of the valley containing the main Metasequoia population] has resulted in considerable damage to the local vegetation. Both Chu and Cooper and Gressitt reported that the forests had largely been destroyed by the time of their visits, and even the Metasequoia communities showed signs of alteration due to man’s activities. We found that conditions had deteriorated even more since these reports. Our observations indicate that there has been so much human and domestic animal disturbance that there are very few plants now associated with Metasequoia. However, there are areas in Xiaohe Commune, particularly in side ravines and on slopes on the east side of the main valley, where secondary forests are developing. Although these areas are close to the Metasequoia groves, they are separated by cut-over slopes and cultivated fields from the riparian areas occupied by Metasequoia. Comparison of the present condition of the forests with photographs taken in 1948 shows considerable destruction during the past 32 years. We were told that many large trees, particularly Castanea henryi and C. mollissima were cut in the mid to late 1950s during the Great Leap Forward to make charcoal for smelting iron. However, no significant amount of iron was ever produced.
The protected status currently given by the government to the remaining naturally occurring trees of Metasequoia will probably insure their survival for the immediate future, but the lack of protection for the surrounding habitat will likely result in little, if any, natural reproduction. The thickets that Chu and Cooper mentioned as being around many of the trees are no longer there, and it was in those habitats that they reported finding seedlings and small trees of Metasequoia. The efforts to monitor the natural populations of Metasequoia may have resulted in disturbance and clearing of other vegetation, thereby contributing to the destruction of suitable germination sites.
References
Chaney, R. W. 1948. The bearing of the living Metasequoia on problems of Tertiary paleobotany. Proceedings of the National Academy U.S.A. 34; 503-515.
Chu, K. L., and W. C. Cooper. 1950. An ecological reconnaissance in the native home of Metasequoia glyptostioboides. Ecology 31: 260-278.
Gressitt, J. L. 1953. The California Academy-Lingnan dawn-redwood expedition. Proceedings of the California Academy of Science 28: 25-58.
Hu, S. Y. 1980. The Metasequoia flora and its phytogeographic significance. Journal of the Arnold Arboretum 61: 41-94 (also, http:// www.herbaria.harvard.edu/china/ HarvardPapers/hu-shui-yingl980.htm).
Liu, Y. C., X. T. Zhou, and P. L. Su. 1978. Shuisha. Hubei: Hubei People’s Press (in Chinese).
Bruce Bartholomew, leader of the expedition in 1980, was then at the University of California Botanical Garden in Berkeley. Presently he is at the California Academy of Sciences. David Boufford was at the Carnegie Museum of Natural History in 1980, but soon thereafter moved to the Harvard University Herbaria. Stephen A. Spongberg, then at the Arnold Arboretum, has recently moved to Martha’s Vineyard, Massachusetts, where he is director of the Polly Hill Arboretum.
Excerpted from “ Metasequoia glyptostroboides—Its Present Status in Central China,” Journal of the Arnold Arboretum (1983) 64: 105-128.
*Richard Howard’s account of his 1978 visit to China was published in Arnoldia (Nov./Dec. 1978) 38(6): 218-237. See also Stephen A. Spongberg, A Reunion of Trees (Cambridge: Harvard University Press, 1990), 238-239.
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