Integrated Conservation for Parakmeria Omeiensis (Magnoliaceae), a Critically Endangered Plant Species Endemic to South-West China

Integrated conservation for Parakmeria omeiensis (Magnoliaceae), a Critically Endangered plant species endemic to south-west China

D AOPING Y U ,XIANGYING W EN,CEHONG L I ,TIEYI X IONG,QIXIN P ENG X IAOJIE L I ,KONGPING X IE,HONG L IU and H AI R EN

Abstract Parakmeria omeiensis is a Critically Endangered tree attractive and large, and their seed arils are orange, making species in the family Magnoliaceae, endemic to south-west the tree an attractive ornamental plant. However, the species China. The tree is functionally dioecious, but little is known has a restricted range. It has been considered a Grade-I about the species’ status in the wild. We investigated the Key-Protected Wild Plant Species in China since  and range, population size, age structure, habitat characteristics has been categorized as Critically Endangered on the and threats to P. omeiensis. We located a total of  individuals IUCN Red List since  (China Expert Workshop, ), in two populations on the steep slopes of Mount Emei, Sichuan the Chinese Higher Plants Red List since  (Yin, ), and province, growing under the canopy of evergreen broadleaved the Red List of Magnoliaceae since  (Malin et al., ). forest in well-drained gravel soil. A male-biased sex ratio, lack The tree has also been identified as a plant species with an of effective pollinating insects, and habitat destruction result extremely small population (Ren et al., ; State Forestry in low seed set and poor seedling survival in the wild. We Administration of China, ). have adopted an integrated conservation approach, including Parakmeria includes five species (P. nitita, P. lotungensis, strengthening in situ conservation, cultivation of saplings, ex P. kachirachirai, P. yunnanensis and P. omeiensis), distributed situ conservation and reintroduction, to protect this species. throughout south-east and south-west China. All species in The successful conservation of P. omeiensis has important im- the genus have male and perfect flowers on different plants plications for the conservation of the genus Parakmeria and and are thus morphologically androdiecious. The genus is con- the family Magnoliaceae. sidered to represent a transition from bisexual to unisexual flowers (Liu, ;Xu,;Chenetal.,). Androdioecy is Keywords China, Critically Endangered species, cryptic a rare breeding system in angiosperms (Listen et al., ; dioecy, integrated conservation, Magnoliaceae, narrow Fritsch & Rieseberg, ;Pannell,), and some studies distribution, Parakmeria omeiensis, reintroduction have shown that androdiecious flowers are functionally dioecious (i.e. cryptic dioecious), with the morphologically perfect flowers being functionally female (Schlessman et al., ; Mayer & Charlesworth, ; Sun et al., ). When the Introduction sex ratio of dioecious species is : in a population, it can maximize seed yield (Lloyd & Webb, ), but sex ratio is he tree species Parakmeria omeiensis (Magnoliaceae) is often male-biased (Mayer & Charlesworth, ). endemic to south-west China. It was described as the T The following factors have been suggested as threats to type species of the genus Parakmeria (Hu & Zheng, ). species of Parakmeria: habitat destruction, logging, a narrow The earliest specimen was collected from Mount Emei in range, low seed yields, low germination rates, and lack of the city of Leshan in Sichuan province. Parakmeria omeiensis protection (Xu, ; Deng et al., ). Improved knowl- is evergreen, can reach – m in height and blooms from edge of the pollination biology and breeding systems of the late April to mid May (Plate ). The flowers are fragrant, genus is required for developing conservation strategies. It has been suggested (Yu et al., ) that in situ conservation

DAOPING YU*, CEHONG LI,TIEYI XIONG,QIXIN PENG,XIAOJIE LI and KONGPING XIE should be improved for threatened species with a cryptic Sichuan Provincial Institute of Natural Resource Science, Chengdu, Sichuan, dioecious breeding system, including monitoring plant sur- China, and Emeishan Botanical Garden, Emeishan, Sichuan, China vival and preventing human disturbance, and that these XIANGYING WEN*† and HAI REN (Corresponding author, orcid.org/0000-0002- 3744-8007) Guangdong Provincial Key Laboratory of Applied Botany, South approaches should be coupled with ex situ conservation to China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, maintain genetic diversity for potential reintroductions. China. E-mail [email protected] Individual P. omeiensis trees with perfect hermaphroditic HONG LIU Department of Earth and Environment, International Center for flowers were first found on a steeply sloping ridge of Mount Tropical Botany, Florida International University, Miami, USA Emei at an altitude of , m(Wu&Wu,). We began to *Contributed equally collect seeds from all fruiting female trees of the Biandanyan †Also at: Botanic Gardens Conservation International, Richmond, UK population during –, germinating them at Emeis- Received  April . Revision requested  July .  Accepted  August . First published online  June . han Botanical Garden and obtaining seedlings. The first

Oryx, 2020, 54(4), 460–465 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International. doi:10.1017/S003060531900111X Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 27 Sep 2021 at 02:42:37, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S003060531900111X Integrated conservation 461

PLATE 1 The flower (a, b), fruit (c) and an individual of Parakmeria omeiensis (d).

individual grew from seed to  m high and began flowering Magnolia denudata,fromMarch to March ,asa in May .By,  individuals had flowered. propagation experiment. All seedlings were transplanted into Only preliminary studies have been conducted on the nursery bags, with mixed humus and pearlites, at least  year associated plant communities (Zhuang et al., ), tissue before they were planted out. We carried out reintroductions culture (Chen & Ma, ; Yu et al., ) and breeding sys- (sensu IUCN, )attwosites(Fig. ): Zhanglaoping is within tems of P. omeiensis (Yu et al., ). Here we provide up- the known range of the species and Xixinsuo is close to dated information on the species’ range and population size, the known range. We reintroduced both grafted female plants investigate population structure and threats to the species, and seedlings of unknown sex. In March of each of –, and develop an integrated conservation strategy. c.  individuals were outplanted into evergreen broadleaved forests at ,–, m altitudes on Mt Emei.

Methods Results To identify the range of P. omeiensis,wereviewedtheFlora ofChina(Xiaetal.,) and other literature, and examined Range and habitat all specimens of the species in the herbaria of the Chinese – Academy Sciences. We reassessed the populations based on From field surveys and herbarium studies during ,  data collected during –,confirmingthatallknownP. we found only two populations, km apart, at Biandanyan       omeiensis are located on the north-east and north-west slopes ( km ) and Shisungou ( . km ), with a total of asso-    of Mt Emei, in south-west Sichuan Province, China (Fig. ). ciated vascular plant species ( tree, shrub, herb During – we recorded the altitude, slope and soil and three vine species). The plant community is a subtrop-   type where the species is found. To investigate the size struc- ical evergreen broadleaved forest, with . % of individual ture of P. omeiensis populations, we measured the height, trees being evergreen. The climate is subtropical, with abun- diameter at breast height (DBH, for tree, height . . m), dant rain and fog and warm, humid monsoons. The plant and crown area of all plants located. We established three communities in the two areas are similar, dominated by  ×  m plots to survey all tree species and five  ×  m sub- species of the families Magnoliaceae and Lauraceae. The – plots within each plot to survey shrubs and herbs. During canopy is m high, the plant community comprises – we interviewed eight local managers of the Mt one tree layer, one shrub layer and one herb layer, and – Emei Scenic Spot and seven local villagers, to investigate plant cover was %. Parakmeria omeiensis was scat- – – any factors affecting the species. tered within the Michelia martini Neolitsea levinei – In the flowering period (April–May) at Emeishan Lithocarpus cleistocarpus Sinarundinara nitida community  –  – Botanical Garden during –, flower visiting insects at altitudes of , , m on slopes of °. The   were caught and identified. We also carried out bagged pol- average soil pH was . , and soil was well-drained gravel       lination experiments using the ex situ population, to assess with . % organic matter, . % nitrogen and . % fruit-set from hand-pollination (cross-pollination with pol- phosphorus. We observed Near Threatened Tibetan rhesus len from a male tree) and self-pollination. As a control treat- monkeys Macaca thibetana frequently; they sometimes ment we used untreated flowers that were accessible to damaged branches and immature fruits of P. omeiensis. natural pollinators. We used  flowers for each treatment. Seeds were collected from the Emeishan Botanical Garden Population structure in mid September –, stored in a refrigerator for  months and sown in garden soil in March of each of the fol- We found a total of  individuals of P. omeiensis in the two lowing years. We grafted P. omeiensis scions to rootstocks of populations:  in Biandanyan,  of which flowered during

FIG. 1 The current distribution of Parakmeria omeiensis, showing the location of the two extant populations (at Shisungou and Biandanyan), the two reintroduction sites (Xixinsuo and Zhanglaoping) and the location of Emeishan Botanical Garden, where the species is cultivated.

our fieldwork ( male and  female trees, on the lower slopes and more sunny higher slopes, respectively), and nine in Shisungou, where only two male trees flowered and there were no individuals with perfect flowers (Fig. ). The sex ratio of flowering individuals in Biandanyan was male-biased, with a ratio of . male: female. We grouped the  individuals into seven size categories (Fig. ), based on height for smaller individuals and DBH for larger individuals. Size structure was of the spindle type, indicating poor natural regeneration (Fig. ).

Conservation status

In interviews, the local managers and villagers suggested that a narrow geographical range, a small area of occupancy, small FIG. 2 The size structure (H, height; DBH, diameter at breast population size, the low number of mature individuals, and height) of  P. omeiensis individuals in the wild. fragmentation of the original population were major factors affecting the species. Based on our findings, we reassess the Pollination and grafting extinction risk (IUCN Standards and Petitions Subcommittee, )forP. omeiensis as Endangered based on criteria Ca(i); We found that hand-pollination increased fruit set compared i.e with , , mature individuals (C) and with a continu- to natural pollination. The mean fruit set of hand pollinated ing decline inferred in numbers of mature individuals ()and flowers was . ± SE .%, with . ± SE . seeds per fruit, no subpopulation estimated to contain .  mature individ- nearly twice that of . ± SE .% fruit set and . ± SE uals (a(i)). In addition, with , , mature individuals in . seeds per fruit in the natural pollination. We observed the wild and ,  in each isolated population, an extremely six insect species (Apiscerana fabricius, Xylocopa sinensis, limited distribution range, pressures from habitat destruc- Haltica cyanea, Meligethes aeneus, Frankliniella intonsa, tion, and occurrence in an area of high plant diversity and and Cecidomyiinae sp.) visiting flowers under natural con- poor economic development (Yu et al., ; Tao et al., ), ditions during informal observations, but only M. aeneus P. omeiensis should continue to be considered as one of the and F. intonsa are effective pollinators. The duration of stig- Plant Species with Extremely Small Populations. ma receptivity was short (.– h). There was little pollen on

TABLE 1 Seed germination rate and growth of seedlings of Parakmeria omeiensis. The seeds were collected from Emeishan Botanical Garden and planted in the garden.

Mean height of Mean basal diameter of Year No. of seeds No. that germinated Germination rate (%) 1-year old seedlings (cm) 1-year old seedlings (cm) 2016 405 260 64.2 16.8 0.32 2017 160 110 68.8 15.6 0.30 2018 720 580 80.6 17.2 0.35

TABLE 2 Survival rate and growth of grafted saplings.

Date Bud type No. of grafts No. surviving Survival rate (%) Mean height of 1-year old saplings (cm) March 2016 Axillary 500 350 70.0 44.5 April 2017 Axillary 440 240 54.5 37.8 March 2018 Terminal 300 210 70.0 52.6

TABLE 3 Survival rate and growth of transplanted saplings in three botanical gardens.

No. of No. Survival rate Mean height Mean basal diameter Mean no. of Location saplings surviving (%) (cm) (cm) branches Chengdu Botanical Garden 50 41 82.0 9.6 0.32 4.3 West China Subalpine 30 24 80.0 10.6 0.38 4.7 Botanical Garden Kunming Botanical Garden 50 35 70.0 11.4 0.40 4.8

TABLE 4 Survival rate and growth of saplings at reintroduction sites.

Altitude No. of No. Survival rate Mean height Mean basal Mean crown Mean no. of Year (m) saplings surviving (%) (cm) diameter (cm) width (cm) branches 2016 1,500–1,550 120 93 77.5 92.7 1.31 52.6 × 43.0 9.9 2017 1,300–1,350 220 212 96.4 111.0 1.37 59.7 × 50.4 11.6 2018 1,200–1,350 160 154 96.3 106.5 1.34 55.4 × 46.8 10.7

perfect flowers, and they did not germinate on the stigma. No Administration set up three patrol zones within the species’ fruit set from self-pollination treatments, indicating that pol- range, and we set up three camera traps (Onick, Wuhan, len from the morphologically perfect flowers was not viable, China) to monitor any disturbance. Together these monitor- rendering the trees that bear these flowers functionally ing efforts resulted in a decline from  thefts of plants in female. The sexual system is xenogamous, and thus pollen  to none in . We transferred  of the plants that must be collected from male plants for hand-pollination to we produced to three other Botanical Gardens (Table ). ensure seed production. Of the , seeds collected during The survival rate of plants in Chengdu Botanical Garden – from Emeishan Botanical Garden, a total of  was lower than at the other two Botanical Gardens, mainly seedlings were obtained (Table ), and  of  grafted because of interference by tourists and the effects of heavy saplings were female (Table ). rainfall. Amongst the reintroduced plants, survival rate after  years was .% at altitudes of ,–, m and    –   Integrated conservation . % at altitudes of , , m(Table ). We found that in  the soil was so wet at the first site (,–, m) To protect P. omeiensis we used an integrated conservation that moss grew on the base of some saplings (soil water con- strategy involving in situ and ex situ conservation, and re- tent reached .%). The moss inhibited soil aeration and introduction. The establishment of the Davidia involucrata resulted in the death of roots. Twenty-one saplings died as Nature Reserve in  within the range of P. omeiensis a result of these conditions. Six saplings planted by the road- effectively protected the species habitat. The local Forest side were killed by tourists, who broke branches.

Discussion gardens, to assist the ongoing conservation translocation efforts. Parakmeria omeiensis is a relict tree species of the Pa- In summary, P. omeiensis is a Critically Endangered, cryp- leotropical flora from the Tertiary period, with a narrow tic dioecious plant endemic to south-west China. Threats to range. Our experimental results indicated that P. omeiensis the species include a male biased sex ratio, poor natural re- is cryptically dioecious. It relies on outcrossing and the generation, and climate change. We propose three principal pollination services of insects to produce fruits and seeds conservation measures: hand-pollination, increasing female: but the required pollinating insects, at least in Emeishan maleratiobygraftingandplantingknownfemaleplantsinre- Botanical Garden, are few, resulting in low fruit set. We introduced populations, and conducting ex situ conservation also observed seeds destroyed by monkeys. We confirmed experiments in botanical gardens. The aims are to achieve a that the sex ratio of P. omeiensis is male biased. There is a balanced sex ratio, increase the probability of seed set and tendency for male bias in tree species, limiting seed produc- seedling recruitment, and enable the species to respond to  tion (Sinclair et al., ). The uneven sex ratio may be the climate change. This integrated conservation approach could result of a number of factors, including human disturbance provide a reference for developing conservation strategies and environmental conditions such as nutrients, humidity, for other threatened, cryptic dioecious plant species. light and elevation. Environmental stresses induces male- ness because female reproductive costs are higher than Acknowledgements This research was supported by Botanic that of a male (Freeman et al., ). In addition, female Garden Conservation International (Grant No. BGCI 30414) and trees tend to be less vigorous and more susceptible to Sichuan Science and Technology Department (Grant Nos 2017  SZ0090, 2017 YSKY0009, 2017TJPT0058). We thank the local forestry environmental changes than male trees (Sun et al., ; administration, staff from Chengdu Botanical Garden and West China Sinclair et al., ), which can result in a lower survival Subalpine Botanical Garden, and local villagers for their participation rate for female trees. in the conservation activities; Daojun Qi and Fujun Li for their help The climate of Mt Emei is changing, with ambient tem- with fieldwork; Wanjun Zhang, Xunling Chen and Suqin Qi for mon- peratures increasing and rainfall decreasing, especially in itoring outplanted saplings; and two anonymous reviewers for their constructive comments. winter (Chen et al., ; Yu & Liu, ). We have found that P. omeiensis seeds are underdeveloped and physiological- Author contributions Study design: DY, XW, HR; fieldwork: CL, ly dormant at the time of dispersal (Yu et al., ), yet seeds DY, TX, QP, XL, KX, HR, XW; data analysis, writing: DY, XW, HL, HR. need high water content during dormancy to maintain their viability. Climate change and reproductive challenges could Conflicts of interest None. put this species at a high risk of extinction; effective conserva- Ethical standards This research abided by the Oryx guidelines on tion will require intervention. Species with small population ethical standards and was conducted under permits from Sichuan sizes are particularly susceptible to climate change (Rehnus Provincial Institute of Natural Resource and Emeishan Forestry Ad- et al., ) and an integrated conservation strategy is essen- ministration. All intellectual property rights regarding data and results tial. As part of this, we increased the female:male plant ratio by were managed within the legal requirements in China and were shared grafting branches of known female plants and transplanting fairly among participants. Reintroduction experiments adopted the highest precautionary standards to avoid accidental introduction and them into the wild. Reintroduction is an important way to re- distribution of invasive and pathogenic organisms, and followed construct threatened plant populations (Liu et al., ; Ren, IUCN/Species Survival Commission guidelines. ), increase range and abundance, and reduce the risk of extinction (Liu et al., ; Sergei, ). Grafted female plants and seedlings grew well at altitudes of ,–, m. More References  than % of grafted plants developed new roots. However,   –  CHEN, C., PANG, Y.M. & ZHANG,Y.F.( ) Study on the some saplings at altitudes of , , m died and the sur- characteristics of climate change in Sichuan basin in the recent vival rate of this out-of-range introduction was lower than the  years. Journal of Southwest University, , –. other within range introduction. We will carry out further CHEN, H.F., ZHANG, R.J., ZHOU, J.S., XING, F.W. & ZENG, Q.W. () research on the effects of soils at the three sites on the growth Distribution and conservation strategy of Endangered Parakmeria  – of the species. lotungensis. Plant Science Journal, , . CHEN,Y.&MA, M.D. () Axillary bud and callus induction of Although the current extant range of P. omeiensis is nar- stem segment Endangered plant of Parakmeria omeiensis. Forestry row, its potential ecological range is wider, as can be seen Science & Technology, , –. from the fact that it grows and develops normally in ex CHINA EXPERT WORKSHOP () Magnolia omeiensis.InThe IUCN situ collections in southern China (Table ). By translocat- Red List of Threatened Species : e.TA. dx.doi.org/.       ing grafted plants and seedlings to locations both within and /IUCN.UK. - .RLTS.T A .en [accessed March ]. beyond the species’ current range, we can help conserve the DENG, X.M., XI, R.C. & FU, S.G. () Establishment of highly species in the face of climate change. We will also continue efficient regeneration system of Parakmeria lotungensis. Acta ex situ conservation efforts for this species in botanical Agriculturae University Jiangxiensis, , –.

FREEMAN, D.C., HARPER, K.T. & CHARNOV, E.L. () Sex change REN, H., ZHANG, Q.M. & LU, H.F. () Wild plant species with in plants: old and new observations and new hypotheses. Oecologia, extremely small populations require conservation and , –. reintroduction in China. Ambio, , –. FRITSCH,P.&RIESEBER, L.H. () High outcrossing rates maintain SCHLESSMAN, M.A., LOWRY, Y.P.P. & LLOYD, D.G. () Functional male and hermaphrodite individuals in populations of the flowering dioecism in the New Caledonian endemic Polyscias pancheri plant Datisca glomerata. Nature, , –. (Araliaceae). Biotropica, , –. HU, X.S. & ZHENG, W.J. () A new genus—Parakmeria Hu et SERGEI,V.() Securing a future for China’s plant biodiversity through Cheng of Magnoliaceae in the southwest of China. Acta Phytotaxon an integrated conservation approach. Plant Diversity, , –. Sin, , –. SINCLAIR, J.P., EMLEN,J.&FREEMAN, D.C. () Biased sex ratios in IUCN () Threats Authority File v. .. iucnredlist.org/info/ plants: theory and trends. The Botanical Review, , –. major-threats [accessed  February ]. STATE FORESTRY ADMINISTRATION OF CHINA () The Saving and IUCN () Guidelines for Reintroductions and Other Conservation Conservation Programme for Extremely Small Populations in China. Translocations. Version .. IUCN, Gland, Switzerland. State Forestry Administration of China, Beijing, China. [In Chinese] IUCN STANDARDS AND PETITIONS SUBCOMMITTEE () SUN, B.L., ZHANG, C.Q., LOWRY, P.P. & WEN,J.() Cryptic dioecy Guidelines for Using the IUCN Red List Categories and Criteria v. . in Nyssa yunnanensis (Nyssaceae), a Critically Endangered species iucnredlist.org/documents/RedListGuidelines.pdf [accessed from tropical Eastern Asia. Annals of the Missouri Botanical Garden,  March ]. , –. LLOYD, D.G. & WEBB, C.J. () Secondary sex characters in plants. TAO, L.D., HAN, C.Y., SONG,K.&SUN, W.B. () A tree species Botanical Review, , –. with an extremely small population: recategorizing the Critically LISTEN, A., RIESEBERGL,H.&ELIAS, T.S. () Functional Endangered Acer yangbiense. Oryx, published online  January . androdioecy in the flowering plant Datisca glomerata. Nature, WU, J.L. & WU, G.D. () New discovery of Parakmeria omeiensis. , –. Journal of Botany, , . LIU, H., REN,H.&LIU,Q.() The conservation translocation of XIA, N.H., LIU, Y.H. & NOOTEBOOM, H.P. () Magnoliaceae. In threatened plants as a conservation measure in China: a review. Flora of China (eds Z. Wu & P. Raven), pp. –. Science Press, Conservation Biology, , –. Beijing, China, & Missouri Botanical Garden Press, St. Louis, USA. LIU, Y.H. () A preliminary study on the taxonomic system of XU, F.X. () Study on pollen morphology of Parakmeria Magnoliaceae. Acta Phytotaxon Sin, , –. lotungensis. Guihaia, , –. MALIN, R., EMILY, B., LYDIA,M.&SARA,O.() The Red List of YIN,H.() The Chinese Higher Plants Red List. Chinese Forestry Magnoliaceae. Revised and Extended. Botanic Gardens Press, Beijing, China. Conservation International, Richmond, UK. YU, D.P., LI, C.H., DING, J., XIE, K.P. & ZHANG, G.Z. () MAYER, S.S. & CHARLESWORTH,D.() Cryptic dioecy in flowering Preliminary report on character of seed and seed culture in vitro of plants. Trends in Ecology & Evolution , –. Parakmeria omeiensis. Resource Develop & Market, , –. PANNELL, J.R. () The evolution and maintenance of androdioecy. YU, D.P., LI, C.H., WEN, X.Y., LI, X.J., PENG, Q.X. & XIE, K.P. () Annual Review of Ecology and Systematics, , –. Flowering biology and breeding system of Parakmeria omeiensis. REHNUS, M., BOLLMANN, K., SCHMATZ, D.R., HACKLÄNDER,K.& Guihaia, , –. BRAUNISCH,V.() Alpine glacial relict species losing out to YU,Y.W.&LIU, X.N. () Influence of global warming to climate climate change: the case of the fragmented mountain hare tourism resources in Sichuan Province. Journal of Anhui population (Lepus timidus) in the Alps. Global Change Biology, Agricultural Sciences, , –. , –. ZHUANG, P., LIU, R.Y. & LIANG, K.H. () A preliminary study on REN,H.() The role of botanical gardens in reintroduction of phytocoenological characters of Parakmeria omeiensis community. plants. Biodiversity Science, , –. Guihaia, , –.