October 9, 2008

Preliminary conclusions:

  • Cryphonectria was confirmed by isolation on Castanea mollissima and C. henryi, and cankers or lesions that appeared to be blight were common on all three species (this would have to be confirmed by systematic isolation). However, the cambium appeared to be generally uninjured by these lesions, and trees were thriving despite the presence of the disease.

  • Castanea mollissima in native forest habitats was somewhat more tree-like than we regard it in the United States.Castanea henryi is the largest and most forest-tree-like of the three native chestnuts, but all became timber trees. C. seguinii was larger than is reported in the literature.

  • Potential collaborators at Dalaoling are Dr. Shen Zehao, Dr. He Wei, and Mr. Xu Shen-Dong (who seems eager to raise the status of his forest preserve).

  • Potential collaborators at Ankang (Nan Gongshan National Park) are Dr. Lu Zhoumin, Mr. Chen, and Mr. Liao.

Friday, September 12, 2008

Travel to Yichang, Hubei Province, with Dr. Shen Zehao, Peking University, and Dr. He Wei, forest pathologist at the Beijing Forestry University, and Xu Yan, escort from the Ministry of Agriculture.

Ms. XU Yan
No. 11, Nongzhanguan Nanli Nanli,
100125, Beijing, China
phone: 86 (10) 59192620

Dr. SHEN Zehao
Associate Professor of Ecology
Department of Ecology
Peking University
Beijing, China 100871
Tel/Fax: 86-10-62751179
Mobile: 86-13-810337189

Dr. HE Wei
Professor of Forest Pathology (?)
Department of Forest Protection
Beijing Forestry University
phone (office): 010-62337731-603
phone (cell): 13520517066

Met in Yichang by:

XU Shen-Dong, Director of the Dalaoling Natural Preserve
Hubei Shanxia Dalaoling Natural Preserve
Den Chun, Yi-Ling District
Yichang City, Hubei Province
Phone (office): 0717-6911698
Phone (cell): 13908607349


DU Zhi-Hu, Deputy Director of Forestry for Yichang
Phone (office): 0717-6344726

Saturday, September 13

Travel to Dalaoling Forest Preserve, about 60 miles as the crow flies from Yichang, north of the Yangtze River.

Visited the preserve's herbarium and viewed a relief map of the area. Spent the afternoon walking through two areas of the preserve, scouting for chestnuts.

The preserve is about 25 square miles and has been protected against cutting since 2001. (But we were also given the figure of 5000 acres, about 8 square miles, for the size of the preserve.) The average elevation is about 5580 feet . Temperature ranges from 5°F to 82°F. The elevation at our study areas was about 4920 feet but the highest areas are about 6560 feet. The latitude is 31° north and the longitude 110.9° east. The forest preserve lies astride an unusual granitic outcropping in an otherwise sedimentary (sandstone, siltstone, and/or limestone) rock terrain, and all the chestnuts we observed were on this highly weathered granitic substrate. The local topography resembles karst and might be called "granitic karst" in that geomorphology is determined by deep chemical weathering under thick soil cover; compare with analogous terrain in the uplands of Venezuela.

Species in the herbarium included: Lindera erythrocarpa, Elaeagnus wushanensis, Celastrus orbiculatus, Lithocarpus cleistocarpus, Acer amplum, Acer flobellatum, Ligustrum sp., Rhus chinensis, Ostrya japonica, Carpinus fargesii, Aesculus wilsonii, Liquidambar formosana, Albizia julibrissin, Parthenocissus sp., Acer davidii, Aralia chinensis, Acer henryi, Liriodendron chinense, Magnolia sp., Betula sp. (bark like B. lenta), Castanea mollissima, C. henryi, C. seguinii.

Photos of additional species of possible interest from today and subsequent days: Cornus controversa, Quercus aliena, Quercus serrata, Stewartia sp., Cercidiphyllum sp., Tilia sp., Fagus lucida, Prunus cerassus, Cyclobalanopsis sp., Davidia involucrate, Rhododendron sp., Pinus armandii, Sassafras sp., Tsuga sp., Diospyros sp.

Spellings will have to be checked against Xu's flora of the area.

Sunday, September 14

Spent the morning examining Castanea henryi (zhui li) and C. mollissima (ban li) along the jeep road that parallels Pig Trough Creek. In the afternoon hiked about 600 feet higher in elevation along a tributary to Pig Trough Creek to Shen Zehao's 5-acre research plot. We found C. henryi and C. seguinii (mao li) on the plot. All the chestnuts on the plot, which lies in a hollow at the head of a stream, were tall and straight, true forest trees. We measured one putative C. seguinii at 87 feet in height and 17.5 inches in DBH, and this is a small tree according to all references. These trees were truly the equal of C. dentata of equal height in "timber form." The trees along the jeep road were shorter and seemed to have more cankering, but they were also more open-grown and are subject to harvesting by the locals, who climb the trees and beat the trunks and branches to dislodge nuts. It should also be mentioned that many of these trees were damaged by a recent (2008?) spring ice storm, which caused significant damage to some tree crowns. This may have been especially true of the open-grown trees along the jeep road.

In general, disturbance has played a large role in the history of these stands. It seemed apparent that there is hardly anywhere in the region that has escaped major disturbance either directly or indirectly from human activities. Probably the most remote and pristine place we visited was Zehao's test plot in the high saddle at Dalaoling. But it was apparent that major disturbance (probably the 1980 selective logging) had a major effect here. Several of the larger chestnut trees had multiple stems and the remains of large (2- to 4-inch diameter) lower branches embedded in the lower trunk. This suggests release of sprouts from a stump or damaged seedling, and an early spurt of growth in nearly open conditions. Subsequent canopy closure would have then shaded out those big side branches. One byproduct of this condition is that we can probably use the size of the trees to estimate growth rate since they have achieved their present 12 - 18 inch diameters in the 28 years since logging. Songlin believes that vegetation in Nan Gongshan near Ankang (discussed below) has had less human impact, especially on the steeper slopes. It is less populated there and near a temple. Forests near temples are less likely to be harvested because of cultural reasons.

We saw a significant number of advance regeneration Quercus seedlings, but very little chestnut. The smaller chestnut trees we saw were all poorly formed sprouts struggling to grow from the base of bigger trees that had been damaged. There were some chestnut seedlings less than a few years old growing in the litter, but a complete absence of larger, "established" seedlings under forest canopies. In contrast, there were numerous healthy chestnut seedlings and small saplings along the edges of the jeep road and on loose soil of small landslides around the road. In fact, the seedling population of these openings was dominated by chestnut and birch.

Fred Paillet points out that the one definite point we have to work from is the recognition that Zehao's plot probably does form the basis of a scientific sampling of chestnut. We verified that the location did have a lot of chestnut, and saw that it was relatively less disturbed than much of the rest of the forest. If the species can be identified, the data set could say a lot about the relative location of the three different chestnut species and their habitat preferences. Since the site was subject to at least one known disturbance event in 1980, we have the possibility of using tree rings to project the stand history back in time. This might be, for example, something like Lorimer's famous reconstruction of the disturbance cycle in the Kilmer Grove. [Lorimer, C., G., 1980, Age structure and disturbance history of a southern Appalachian virgin forest, Ecology, v. 61, no. 5, p. 1169-1184] So it seems that we do have enough of a preliminary sampling to formulate questions, and analysis of the data from Zehao's plots could provide answers to those questions. We could pose the study in just that frame, with the expectation that we would help Zehao and the student who actually ends up doing the analysis publish their results in a western journal such as the Torrey Bulletin or the Canadian Journal of Botany. We should make it clear that this is their data set and we are not attempting to take credit from it in any way.

Monday, September 15

Shen Zehao left us this morning and He Wei will leave tomorrow morning.

Spent the morning surveying trees along the upper part of the jeep road along Pig Trough Creek, climbing up away from the road at one point along a narrow ridge. Finally found some definite chestnut blight according to Drs. Hebard and He. The trees along the road are C. mollissima and C. henryi and tend to be poorly formed, short, and heavily cankered. Of course, they are also more-or-less open-grown and frequently growing on cut-bank fill. As mentioned, they have probably been damaged by nut collectors and at least one ice storm. Incidentally, C. henryi and C. seguinii are already dropping burs, or beginning to, but the C. mollissima is not yet doing so.

In the afternoon we split into two groups in order to get data on more trees. Hebard's group went farther down the road and dropped downslope to get some larger, taller, straighter trees that we saw yesterday. Sara, Songlin, and Kim ventured across Pig Trough Creek and climbed the steep slope opposite the road to measure some forest-grown chestnuts that we could see from the jeep road. We measured some handsome C. henryi and C. seguinii, as well as two C. mollissima near the top along another jeep trail that we found - and also on a drier ridge. The C. mollissima seem to favor open areas on dry ridge tops, the C. henryi seem to be more cosmopolitan in this area, and the C. seguinii seem to favor the moister habitats - along the stream today and on the moist bench in Zehao's plot yesterday.

After dinner, the team convened in the conference room to record all data on Sara's computer, and we finished about 9:00 p.m.

We have some doubts that the C. mollissima in this area is actually wild. Some appear to have seeded in naturally, but they may be escapes from cultivation at a slightly lower elevation. There is no doubt, though, that the other two species are growing here wild.

Monday, September 16

Mostly a day of touring - a view from a high point in the reserve, Roaring Tiger Falls, a hunter's house for lunch, etc.

We re-visited the second location that we saw on Saturday. Descended the ridge to take data on 10 more trees. Also visited a C. mollissima nut-production plantation below the reserve where the farmer was having trouble with pre-mature browning and death of some of the burs.

Tuesday, September 17

We returned to Yichang from Dalaoling and traveled by train from Yichang to Ankang, Shaanxi Province, arriving at 2:30 a.m. on the 18th.

Wednesday, September 18

Had lunch at noon with our new hosts:

Mr. CAO, Director of Extension for the Ankang Region (ca. 9000 mi2)
no address

Mr. CHEN Yu-Zhao, Director of Forest Regeneration, Ankang
No. 12 Wen-Chang-Lu Xi-Xiang,
Haibing District,
Ankang City, Shaanxi Province
Phone (office): 0915-3112377
Phone (cell): 13991520058

Dr. LU Zhoumin
Associate Professor, College of Forestry
Northwest Agriculture and Forestry University
No. 3 Taicheng Road
Yangling Shaanxi province, China, 712100
Telephone: +86-029-87082210

Madame TANG, the local Communist Party official for forestry
no address

In the afternoon we toured a chestnut orchard in the Bashan Mountains south of the city and were back by 3:30. We definitely identified active blight on some of these trees, often finding other pathogens superimposed on blight. The severity of blight seemed to vary greatly from tree to tree, impacting growth form on some trees but having relatively little effect on survival and nut crop overall. Blight infection at this site might have been influenced by the apparently marginal fertility and poor pruning practices.

Ankang lies at about 980 feet elevation and we will go to 2300 to 2950 feet in the park we will visit tomorrow. Rainfall is generally less than about 40 inches in this area with a minimum temperature of 16°F. (This seems rather high, but that is what we were told.) Annual average temperature for the region is between 54 and 60°F and precipitation is between 30 and 47 inches. The latitude is 32.6° north and the longitude 109° east.

All 3 species of chestnut grow wild in this area with C. mollissima at lower elevations and up to 6.6 feet in diameter and 82 feet in height. C. henryi and C. seguinii grow at higher elevations and do not get as tall, but (again) C. seguinii is not shrubby in this part of the country. The northern limit of C. henryi is said to be in the mountains to the south of Ankang (the Bashan Mountains, where we will be going) and the northern limit of C. seguinii is said to be in the mountains to the north (the Qinling Mountains that we later traversed on the way to Xi'an). All this information comes from Mr. Chen (see below), who appears to be very knowledgeable about chestnut. He has surveyed wild C. mollissima in other parts of China in a World Bank supported project and has made selections for introduction to the horticultural trade. (Fred P. believes, and Songlin agrees, that these notes about the ranges may be wrong in the opposite way. That is, that C. seguinii has its range limit in the northern edge of the Bashan Mountains south of the Han River, whereas C. henryi reaches its northern limit on the southern side of the Qinling range north of Ankang. This seems to make sense because C. henryi also has a higher elevation range limit, and elevation should correlate with latitude, all else being equal. Songlin is checking.)

Friday, September 19

We were joined today by:

Mr. LIAO, Deputy Director for Forestry in Ankang

Drove southwest into the mountains for 3 hours, finally ending up at Nan Gongshan National Park. After looking at chestnut at lower elevations, we had lunch at the park restaurant. We drove higher into the park in the afternoon, stopping only when the fog made it useless to proceed further. We surveyed chestnut by walking back along the road perhaps one-half mile or so and encountered all three species and our first unequivocally wild C. mollissima. Elevations were in the range of 4400 to 4700 feet. Surveying was difficult here because of the steepness of the slopes above and below the road, measured once at almost exactly 100%.

Notes from conversations with Mr. Chen and Mr. Liao:
(Both persons appear to be very knowledgeable about chestnut.)

C. mollissima occurs at lower elevations in the mountains but C. henryi only shows up above 3280 feet. C. mollissima and C. seguinii occur up to 5250 feet but C. henryi goes up to 5910 feet and is probably more cold tolerant than C. seguinii, at least. C. seguinii tends to prefer valleys and moisture. The maximum height for C. seguinii is about 66 feet, and for C. henryi and C. mollissima about 131 feet, and the latter can get up to about 6.6 feet in diameter. (A Chinese dendrology text we later consulted in Dr. He's office puts the maximum height of C. henryi at 98 feet and the maximum height of C. mollissima and C. seguinii at 66 feet each.) C. mollissima is the most susceptible to blight. C. seguinii rarely gets chestnut blight and C. henryi "never" gets it. C. seguinii tends to fork, so in their experience it is not as good for timber, and C. henryi is considered the best for timber. It is harvested mostly for wood flooring. C. henryi does well in closely spaced plantations, grows with less heavy branching and sprouting, and is "more responsive to sunlight."

Mr. Chen has done selection for nut production in C. mollissima, and they have released two cultivars, An-Li #1 and #2 (An for Ankang and Li for chestnut). He says that nut cultivars are generally more susceptible to blight than naturally occurring C. mollissima, but whether this is because of genetics or growing conditions was not clear.

Chen and Liao are very interested in learning more about the distribution of the three species in the park, their habitat preferences, genetic variation, and the occurrence of blight. This might be a possible avenue of collaboration with Dr. Lu of the Northwest Agricultural and Forestry University - for example, if Lu could send a bright graduate student to University of Kentucky who could do his research in the Bashan. Chen and Liao explicitly invited us back.

Chen and Liao think the occurrence of blight has more to do with incidental factors that increase susceptibility (e.g., insect attacks), than with variation in the pathogenicity of the fungus. The region had a major outbreak of blight in 1997, probably not because of a sudden change (shortly reversed) in the genetic systems of the host and parasite.

According to Chen, who has seen them, there are many more stands of C. mollissima in the Hua Long Shan, a subset of the Bashan Mountains, Zhen Ping County, and also in the Qiling Mountains to the north of Ankang in Ning Shan County. But to access these stands (which are at elevations of 2620 to 3940 feet) one has to walk several miles from the road. Some of these stands are almost pure chestnut (80% or more of total basal area). Chen has cored C. mollissima of 4.3 feet diameter (not clear whether that tree was in these two areas). He has measured every tree and seedling in a plot of 4300 to 5380 square feet and will send data. He has surveyed the entire country for C. mollissima and suggests four form types. The species is very variable according to him and some individuals are quite tree-like (as we saw).

The Bashan Mountains have the highest diversity of subtropical flora in China because they lie at the intersection of subtropical and temperate climatic zones. Boars are abundant, and bears, wolves, and leopards are present.

Saturday, September 20

We returned to Ankang, by the same twisty road, another 3-hour drive, but we took a side trip first to visit a small stand of sapling C. mollissima growing wild in a small patch of forest growing on a 93% slope just above a small village. Mr. Chen and Mr. Liao left us today. After lunch in Ankang, we drove on by bus to Xi'an, where we again met Mr. Cao and Madame Tang. Dr. Lu left us on the 19th.

Sunday, September 21

Tour of the terra cotta soldiers in Xi'An.

Monday, September 22

Return flight to Beijing.

Tuesday, September 23

Tour of the Great Wall. Dinner with Bruce Levine.

Bruce Levine
(MD-TACF member; works for State Dept. in Beijing)
American Embassy Beijing - Econ
PSC 461 Box 50
FPO AP 96521
Home [86](10) 6532-6855
Work [86](10) 6532-3831 ext 6046
Mob [86](13)801289534

Wednesday, September 24

Ersatz debriefing at the U.S. Embassy, reconnection with Dr. He Wei at Beijing Forestry University, reconnection with Dr. Shen Zehao at Peking University, and seminar to faculty and students at Peking University. Dinner with Wei, Zehao, and dinner with all + Dr. Fang Jing-Yun, head of the Department of Urban and Environmental Science.

At Beijing Forestry University, we observed several cultured plates of what appeared to be Cryphonectria parasitica from samples Dr. He had taken from Dalaoling. These cultures seemed to confirm the presence of chestnut blight on at least 2 trees where stroma were not present.

Dr. FANG Jing-Yun
Professor of Plant Ecology
Department of Urban and Environmental Science
Peking University, Beijing 100871 PRC

Additional Notes from Fred Hebard following the International Chestnut Conference

There should be enough good SSR and SNP markers coming out of the NSF Fagaceae genome project to make it feasible to detect whether a population of C. mollissima is native or planted. From a utilitarian point of view, this would seem to me to be a worthwhile project to

undertake, since alleles from wild populations may be useful in cultivar development. TACF also might get access to better alleles for resistance (although C. henryi seems more promising for this at the moment). Parallel collection and analysis of C. parasitica populations on wild C. mollissima also could be informative.

At the International Chestnut Symposium, there were a number of papers on the population genetics of wild Chinese chestnut, so this was definitely on people's minds, at least from the host (C. mollissima) side if not the fungus side. Again, I wonder what the criteria are for assessing that a population is wild. These papers were limited in the number of markers used.

The two most prominent ones were by personnel at the Beijing Academy of Agricultural and Forestry Sciences. The first was by Cheng Li-li and Huang Wu-gang of the Beijing Institute of Forestry and Pomology. They studied genetic diversity using 10 SSRs for wild C. mollissima from the Da Bie Shan, in Ling, and Lian Hua Feng mountainous regions. A fourth region was studied, but a misprint duplicated Da Bie Shan for it. The second paper was by Lan Yan-ping, Zhou Lian-di, Yao Yan-wu, Zhou Jia-hua and Wang Shang-de of the Institute of Agricultural Integrated Development. They used allozymes and morphometric traits to study diversity in 9 populations, including the Yanshan district and the Dabie Mountains. The provinces were Beijing, Hebei, Shandong, Zhejiang, Shanxi (not our Shaanxi), Hubei, Henan, Jiangsu and Anhui. Since Shandong is included, I doubt all these populations were wild, but....