Hostname: page-component-848d4c4894-tn8tq Total loading time: 0 Render date: 2024-06-13T13:51:21.638Z Has data issue: false hasContentIssue false

Distribution and conservation status of Magnolia ovoidea (Magnoliaceae): a Critically Endangered species in Yunnan, China

Published online by Cambridge University Press:  16 October 2019

Chunyan Han*
Affiliation:
Kunming Botanical Garden and Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan650201, China
Lidan Tao
Affiliation:
Kunming Botanical Garden and Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan650201, China
Weibang Sun
Affiliation:
Kunming Botanical Garden and Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan650201, China
*
(Corresponding author) E-mail hanchunyan@mail.kib.ac.cn

Abstract

Magnolia ovoidea is a narrowly endemic, Critically Endangered tree with a fragmented distribution in south-west Yunnan, China. We examined the size structure of this species, documented threats and assessed its extinction risk. We found the species in six locations, all in unprotected areas, in Maguan County. The largest subpopulations are in Donggua Lin and Youfang Po, with 17 and 50 living individuals, respectively. The distribution of the diameter at breast height of the M. ovoidea population has an inverse J-shape, indicating a stable size structure. However, the distribution of the height of seedlings is L-shaped, suggesting inhibited regeneration. The natural vegetation is severely fragmented in all six locations, surrounded by roads, farmlands, and Alnus nepalensis or Cunninghamia lanceolata plantations. We recommend that M. ovoidea should be categorized on the IUCN Red List as Critically Endangered based on criteria B2ab(iii) + C2a(i).

Type
Short Communication
Copyright
Copyright © Fauna & Flora International 2019

The plant family Magnoliaceae has a disjunctive geographical distribution: two-thirds of species occur in Asia, the others in Central America and northern South America (Liu, Reference Liu2004; Cicuzza et al., Reference Cicuzza, Newton and Oldfield2007; Xia et al., Reference Xia, Liu, Nooteboom, Wu and Raven2008). The family comprises c. 314 species, of which 147 (46.8%) are threatened in the wild (Rivers et al., Reference Rivers, Beech, Murphy and Oldfield2016). China and Latin America are the hotspots for Magnoliaceae (Rivers et al., Reference Rivers, Beech, Murphy and Oldfield2016). There are c. 108 species in China, of which 78 are in south-west China (Shui, Reference Shui2003; Xia et al., Reference Xia, Liu, Nooteboom, Wu and Raven2008). This area is a biodiversity hot-spot, with > 13,000 vascular plant species, of which c. 29% are endemic (Chen et al., Reference Chen, Lu, Zhu, Tamaki and Qiu2017). Of these, 38 species belong to Magnoliaceae (Chen et al., Reference Chen, Lu, Zhu, Tamaki and Qiu2017), and one of the most seriously threatened is Magnolia ovoidea (Hung T. Chang and B.L. Chen) V.S. Kumar, categorized as Critically Endangered (Rivers et al., Reference Rivers, Beech, Murphy and Oldfield2016), and as a Plant Species with an Extremely Small Population (Ma et al., Reference Ma, Chen, Grumbine, Dao, Sun and Guo2013).

The first specimen of M. ovoidea was collected in Maguan County, Yunnan, by Baoliang Chen in April 1986 (Chen, Reference Chen1988). We obtained information on this species from Flora Yunnanica (Law, Reference Law and Wu2006), Flora of China (Xia, et al., Reference Xia, Liu, Nooteboom, Wu and Raven2008) and Magnolias of China (Liu, Reference Liu2004), and examined all specimens in the Chinese Virtual Herbarium (CVH, 2015), to determine the species’ range. Based on the specimens and habitat of M. ovoidea, we conducted field surveys in eight counties of Wenshan Prefecture in Yunnan during 2012–2015, during which we also interviewed a total of 24 local foresters from all counties surveyed, showing them photographs and specimens of M. ovoidea, to obtain additional information on the species. Our surveys and the interviews indicated that M. ovoidea occurs only in Maguan County, at altitudes of 1,460–1,700 m.

In October 2016, to investigate the size structure of the population and to assess any potential threats, we surveyed all known populations. We recorded the position of all living individuals with a GPS, noting habitat characteristics and any evidence of disturbance. The Townships of Miechang and Bazhai, Maguan County (Fig. 1), where the known individuals were found, have a mean annual temperature of 22.8 °C, with a mean minimum temperature of −4 °C in January and a mean maximum of 32.3 °C in July (Zhou et al., Reference Zhou, Jiang, Yang, Zhang and Xiang2012), and mean annual total precipitation of 1,254 mm.

Fig. 1 The six known localities (Table 1) of Magnolia ovoidea, in Bazhai and Miechang Townships in Maguan County, Yunnan, China.

Table 1 Characteristics of the six known localities of Magnolia ovoidea in Maguan County (Fig. 1).

For all M. ovoidea located, we recorded the diameter at breast height (DBH) and height of all living individuals ≥ 1.3 tall, and counted and measured the height of all seedlings (height < 1.3 m). A total of 62 individuals ≥ 1.3 m tall and 18 seedlings were recorded (Table 1; Plate 1). As a whole, the DBH of the population has an inverse J-shaped distribution, with most individuals in the 5–10 cm class (Fig. 2). Such a distribution indicates a stable population structure in which naturally senescent individuals are replaced with seedlings and saplings (Tang et al., Reference Tang, He, Gao, Zhao, Sun and Ohsawa2011; Ren et al., Reference Ren, Jian, Chen, Liu, Zhang and Liu2014; Qian et al., Reference Qian, Yang, Tang, Momohara, Yi and Ohsawa2016). However, of the six sites, seedlings were only found in Donggua Lin, Maocao Zhai and Youfang Po, and the distribution of seedling height is L-shaped, with fewest seedlings in the smallest classes. The persistence of small populations usually depends on a few mature plants and is therefore highly vulnerable to factors limiting seedling recruitment (Tang et al., Reference Tang, He, Gao, Zhao, Sun and Ohsawa2011; Qian et al., Reference Qian, Yang, Tang, Momohara, Yi and Ohsawa2016).

Fig. 2 The frequency distribution of (a) the diameter at breast height (DBH) of all living individuals, and (b) the height of all seedlings (height < 1.3 m or DBH < 1.0 cm) of M. ovoidea in Maguan County (Fig. 1).

Plate 1 (a) M. ovoidea seedling, and (b) and (c) adult M. ovoidea in Youfang Po (Fig. 1).

Magnolia ovoidea is threatened by habitat degradation and fragmentation. In the six locations, vegetation clearing for planting of crops is ongoing, and we witnessed M. ovoidea being felled or partially felled (all six locations are in unprotected areas). All locations are surrounded by roads, farmlands, and Alnus nepalensis or Cunninghamia lanceolata plantations (Table 1). The restricted area of vegetation, and human activities, are probably limiting the recruitment of M. ovoidea seedlings.

Rivers et al. (Reference Rivers, Beech, Murphy and Oldfield2016) categorized M. ovoidea as Critically Endangered based on criterion (IUCN, 2012) D (i.e. total number of mature individuals < 50). Our findings support the categorization as Critically Endangered but based on alternative criteria. The total extent of occurrence across the Bazhai and Miechang Townships is 2,600 m2 (< 10 km2), the total number of mature individuals is < 250, and the number of individuals in each subpopulation is < 50, and therefore the appropriate criteria are B2ab(iii) + C2a(i).

For endemic and narrowly distributed species habitat destruction and human disturbance increase the risk of extinction. A small population size and fragmented habitats are likely to reduce the viability of such species (Li et al., Reference Li, Zhang and Zhang2014; Wang et al., Reference Wang, Ma, Chen, Li, Dao and Sun2015). It is not unusual for extremely restricted endemics to survive with < 5 subpopulations (Martinell et al., Reference Martinell, López-Pujol, Blanché, Molero and Sàez2011), and such species may be best managed by local conservation efforts (Crain et al., Reference Crain, Sánchez-Cuervo, White and Steinberg2015), in this case for all of the remaining six populations. We plan to collect seeds for cultivation and ex situ conservation in the Germplasm Bank of Wild Species in Southwest China (Li et al., Reference Li, Yang, Wang and Cai2010), and to study the genetic diversity of this species. Our approach to the conservation of M. ovoidea may be applicable for other plants species with extremely small populations in China (Ma et al., Reference Ma, Chen, Grumbine, Dao, Sun and Guo2013), many of which are threatened.

Acknowledgements

This study was supported by grants from the National Science and Technology Basic Resources Investigation Special Project (2017FY100100), the NSFC-Yunnan Joint Fund (U1602264) and Mohamed bin Zayed Species Conservation Fund (12053820).

Author contributions

Surveys: CH, LT; data analysis: CH, LT, WS; writing: CH; revision: WS.

Conflicts of interest

None.

Ethical standards

This research abided by the Oryx guidelines on ethical standards.

Footnotes

*

Also at: Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, China

Also at: University of Chinese Academy of Sciences, Beijing, China

§

Contributed equally.

References

Chen, B.L. (1988) New taxa of Magnoliaceae from Yunnan. Acta Scientiarum Naturalium Universitatis Sunyatseni, 1, 107112.Google Scholar
Chen, C., Lu, R.S., Zhu, S.S., Tamaki, I. & Qiu, Y.X. (2017) Population structure and historical demography of Dipteronia dyeriana (Sapindaceae), an extremely narrow palaeoendemic plant from China: implications for conservation in a biodiversity hot spot. Heredity, 2, 95106.10.1038/hdy.2017.19CrossRefGoogle Scholar
Cicuzza, D., Newton, A. & Oldfield, S. (2007) The Red List of Magnoliaceae. Fauna & Flora International, Cambridge, UK.Google Scholar
Crain, B.J., Sánchez-Cuervo, A.M., White, J.W. & Steinberg, S.J. (2015) Conservation ecology of rare plants within complex local habitat networks. Oryx, 4, 696703.CrossRefGoogle Scholar
CVH (2015) Chinese Virtual Herbarium v.5.0. http://www.cvh.ac.cn [accessed 19 January 2018].Google Scholar
Li, D.Z., Yang, X.Y., Wang, Y.H. & Cai, J. (2010) The Germplasm Bank of Wild Species, Southwest China. BCAS, 4, 264267.Google Scholar
IUCN (2012) IUCN Red List Categories and Criteria v.3.1. 2nd edition. IUCN, Gland, Switzerland, and Cambridge, UK.Google Scholar
Law, Y.W. (2006) Magnoliaceae. In Flora Yunnanica (ed. Wu, Z.Y.), pp. 163. Science Press, Beijing, China.Google Scholar
Li, B., Zhang, Z. & Zhang, D. (2014) Conservation status of the unique populations of Wenchengia alternifolia, an enigmatic plant endemic to Hainan island, China. Oryx, 3, 354357.10.1017/S0030605313001373CrossRefGoogle Scholar
Liu, Y.H. (2004) Magnolias of China. Science Press, Beijing, China.Google Scholar
Ma, Y., Chen, G., Grumbine, R.E., Dao, Z.L., Sun, W.B. & Guo, H.J. (2013) Conserving plant species with extremely small populations (PSESP) in China. Biodiversity and Conservation, 22, 803809.10.1007/s10531-013-0434-3CrossRefGoogle Scholar
Martinell, M.C., López-Pujol, J., Blanché, C., Molero, J. & Sàez, L. (2011) Conservation assessment of Aquilegia paui (Ranunculaceae): a case study of an extremely narrow endemic. Oryx, 2, 187190.CrossRefGoogle Scholar
Qian, S.H., Yang, Y.C., Tang, C.Q., Momohara, A., Yi, S. & Ohsawa, M. (2016) Effective conservation measures are needed for wild Cathaya argyrophylla populations in China: insights from the population structure and regeneration characteristics. Forest Ecology and Management, 361, 358367.10.1016/j.foreco.2015.11.041CrossRefGoogle Scholar
Ren, H., Jian, S., Chen, Y., Liu, H., Zhang, Q., Liu, N. et al. (2014) Distribution, status, and conservation of Camellia changii Ye (Theaceae), a Critically Endangered plant endemic to southern China. Oryx, 48, 358360.10.1017/S0030605313001324CrossRefGoogle Scholar
Rivers, M., Beech, E., Murphy, L. & Oldfield, S. (2016) The Red List of Magnoliaceae. Botanic Gardens Conservation International, Richmond, UK.Google Scholar
Shui, Y.L. (2003) Seed Plants of Honghe Region in SE Yunnan, China. Yunnan Science and Technology Press, Kunming, China.Google Scholar
Tang, C.Q., He, L.Y., Gao, Z.R., Zhao, X.F., Sun, W.B. & Ohsawa, M. (2011) Habitat fragmentation, degradation, and population status of endangered Michelia coriacea in Southeastern Yunnan, China. Mountain Research and Development, 4, 343350.10.1659/MRD-JOURNAL-D-11-00004.1CrossRefGoogle Scholar
Wang, B., Ma, Y.P., Chen, G., Li, C.R., Dao, Z.L. & Sun, W.B. (2015) Rescuing Magnolia sinica (Magnoliaceae), a Critically Endangered species endemic to Yunnan, China. Oryx, 3, 446449.Google Scholar
Xia, N.H., Liu, Y.H. & Nooteboom, H.P. (2008) Magnoliaceae. In Flora of China, vol. 7 (eds Wu, Z.Y. & Raven, P.), pp. 4891. Science Press, Beijing, China, & Missouri Botanical Garden Press, St Louis, USA.Google Scholar
Zhou, Y., Jiang, H., Yang, W.Z., Zhang, S.S. & Xiang, Z.Y. (2012) Study on stock of Pinus wangii, an extremely small population species. Journal of West China Forestry Science, 3, 8083.Google Scholar
Figure 0

Fig. 1 The six known localities (Table 1) of Magnolia ovoidea, in Bazhai and Miechang Townships in Maguan County, Yunnan, China.

Figure 1

Table 1 Characteristics of the six known localities of Magnolia ovoidea in Maguan County (Fig. 1).

Figure 2

Fig. 2 The frequency distribution of (a) the diameter at breast height (DBH) of all living individuals, and (b) the height of all seedlings (height < 1.3 m or DBH < 1.0 cm) of M. ovoidea in Maguan County (Fig. 1).

Figure 3

Plate 1 (a) M. ovoidea seedling, and (b) and (c) adult M. ovoidea in Youfang Po (Fig. 1).