ARTÍCULO

Special issue on Ecology, evolution, and conservation of plants in China: Introduction and some considerations

J.-Q. LIU (刘建全)¹, M.-X. REN (任明迅)², A. SUSANNA³ & J. LÓPEZ-PUJOL³

¹ Key Laboratory for Bio-resources and Eco-environment, College of Life Sciences, Sichuan University, CN-610065 Chengdu, People’s Republic of China

² College of Horticulture and Landscape Architecture, Hainan University, CN-570228 Haikou, People’s Republic of China

³ Botanic Institute of Barcelona (IBB-CSIC-ICUB), pg. del Migdia, s/n, ES-08038 Barcelona, Spain

E-mail: J. López-Pujol jlopez@ibb.csic.es

ABSTRACT
Special issue on Ecology, evolution, and conservation of plants in China: Introduction and some considerations.— China has one of the world’s richest floras with around 33,000 vascular plants, of which up to 17,000 are endemic. Besides these astonishing figures, the Chinese flora is very interesting from the point of view of evolution, as it shows a strong relictual character with some truly "living fossils" such as Ginkgo biloba or Metasequoia glyptostroboides. At the same time, China probably harbours the most important "evolutionary front" of the world’s temperate flora, the Hengduan Mountains. Unfortunately, the flora of China also includes a high number of threatened species (with nearly 4000), mostly due to the destruction of natural habitats and the over-exploitation of natural resources. This special issue, which corresponds to volume 34 of Collectanea Botanica, is aimed to contribute to the knowledge of Chinese flora through a series of contributions (seven full-length articles and one short note) spanning several topics such as biogeography, conservation, demography, ecology, evolution, and plant-animal interactions.
KEYWORDS: China; endemism; hotspots; richness; threatened species.

Número especial sobre Ecología, evolución y conservación en las plantas de China: introducción y algunas consideraciones

RESUMEN
Número especial sobre Ecología, evolución y conservación en las plantas de China: introducción y algunas consideraciones.— China tiene una de las floras más ricas del mundo con alrededor 33.000 plantas vasculares, de las cuales hasta 17.000 son endémicas. Además de estas cifras asombrosas, la flora china es muy interesante desde el punto de vista de la evolución, ya que muestra un fuerte carácter relictual con algunos auténticos «fósiles vivientes» como Ginkgo biloba o Metasequoia glyptostroboides. Al mismo tiempo, China probablemente alberga el «frente evolutivo» más importante de las floras templadas del mundo, las montañas Hengduan. Por desgracia, la flora de China también destaca por el elevado número de especies amenazadas (casi 4000), sobre todo debido a la destrucción de los hábitats y la sobreexplotación de los recursos naturales. Este número especial, que corresponde al volumen 34 de Collectanea Botanica, tiene como objetivo contribuir al conocimiento de la flora de China a través de una serie de contribuciones (siete artículos y una nota breve) que abarcan varios temas como la biogeografía, la conservación, la demografía, la ecología, la evolución y las interacciones planta-animal.
PALABRAS CLAVE: China; endemismo; especies amenazadas; hotspots; riqueza.

摘要
中国植物生态，进化与保育专辑：导言与思索。— 中国是世界上植物多样性最丰富的国家之一，有着33,000种维管植物，其中约17,000特有植物。除此之外，中国植物区系包含了非常典型的孑遗成分，有着众多野生个体的真正的“活化石”，如银杏、水杉等。中国还有着世界温带植物区系最为重要的“进化热点地”——横断山区。不幸的是，中国植物区系中也存在着极高比例的受威胁物种（约有4,000种），其濒危原因主要是生境的破坏和自然资源的过度采用。本期专辑，Collectanea Botanica 的第34卷，收集了7篇论文、1篇简报，从生物地理学、保育、种群统计学、生态学、进化以及植物-动物相互关系等多个方面对中国植物进行了详细的研究，希望能有助于人们更好地认识中国植物区系。
关键词：中国；特有性；热点地区；丰富度；濒危物种。

CONTENIDOS

China is one of the world’s richest countries in terms of plant diversity, only behind Brazil and Colombia. The estimated number of vascular plant species is about 33,000, with ~30,000 angiosperms, 200–250 gymnosperms, and 2100–2600 pteridophytes. Furthermore, approximately 2200–3000 bryophytes can be found in China (López-Pujol et al., 2006López-Pujol, J., Zhang, F.-M. & Ge, S. 2006. Plant biodiversity in China: richly varied, endangered and in need of conservation. Biodiversity and Conservation 15: 3983–4026. http://dx.doi.org/10.1007/s10531-005-3015-2; Huang et al., 2015aHuang, H.-W., Oldfield, S. & Qian, H. 2015a. Global significance of plant diversity in China. In: Hong, D.-Y. & Blackmore, S. (Eds.), Plants of China – A companion to the Flora of China. Science Press, Beijing: 7–34. ; Wang et al., 2015bWang, L., Jia, Y., Zhang, X. & Qin, H. 2015b. 中国高等植物多样性 [Overview of higher plant diversity in China]. Biodiversity Science 23: 217–224 [in Chinese]. http://dx.doi.org/10.17520/biods.2015049). More relevant are, nevertheless, the rates of endemism of Chinese flora: some 17,000 higher plants (i.e. over 50% of the total) are endemic to China (Wang et al., 2015bWang, L., Jia, Y., Zhang, X. & Qin, H. 2015b. 中国高等植物多样性 [Overview of higher plant diversity in China]. Biodiversity Science 23: 217–224 [in Chinese]. http://dx.doi.org/10.17520/biods.2015049). At the generic level, about 250 genera are endemic, and, at the family level, several families are endemic (Eucommiaceae and Ginkgoaceae) or nearly endemic (e.g. Cercidiphyllaceae, Circaeasteraceae, Rhoipteleaceae, Tetracentraceae, and Trochodendraceae; Huang et al., 2015aHuang, H.-W., Oldfield, S. & Qian, H. 2015a. Global significance of plant diversity in China. In: Hong, D.-Y. & Blackmore, S. (Eds.), Plants of China – A companion to the Flora of China. Science Press, Beijing: 7–34. ). This wealth of species diversity and endemism is attributable to a series of physical and biotic factors, including: (1) a large country’s area (about 9.6 million km²); (2) a complex and extended geological history, with many tectonic events (including the collision of the Indian subcontinent at the Eocene); (3) an unbroken connectivity between tropical, subtropical, temperate and boreal forests; (4) a large proportion of tropical and subtropical habitats; (5) the close connection of China to tropical regions of Southeast Asia; (6) a highly rugged and dissected topography (especially in southern China); and (7) reduced extinction rates during the late Cenozoic global cooling (Axelrod et al., 1996Axelrod, D. I., Al-Shehbaz, I. & Raven, P. H. 1996. History of the modern flora of China. In: Zhang, A. & Wu, S (Eds.), Floristic characteristics and diversity of East Asian plants. China Higher Education Press, Beijing: 43–55. ; Qian & Ricklefs, 1999Qian, H. & Ricklefs, R. E. 1999. A comparison of the taxonomic richness of vascular plants in China and the United States. The American Naturalist 154: 160–181. http://dx.doi.org/10.1086/303230; Qian, 2002Qian, H. 2002. A comparison of the taxonomic richness of temperate plants in East Asia and North America. American Journal of Botany 89: 1818–1825. http://dx.doi.org/10.3732/ajb.89.11.1818; López-Pujol et al., 2011aLópez-Pujol, J., Zhang, F.-M., Sun, H.-Q., Ying, T.-S. & Ge, S. 2011a. Centres of plant endemism in China: places for survival or for speciation? Journal of Biogeography 38: 1267–1280. http://dx.doi.org/10.1111/j.1365-2699.2011.02504.x). The main centres of species richness and endemism are highly coincident in China, and are almost exclusively located in the mountainous regions of central, southern and southwestern provinces (Fig. 1; Tang et al., 2006Tang, Z., Wang, Z., Zheng, C. & Fang, J. 2006. Biodiversity in China’s mountains. Frontiers in Ecology and the Environment 4: 347–352. http://dx.doi.org/10.1890/1540-9295(2006)004[0347:BICM]2.0.CO;2; López-Pujol et al., 2011aLópez-Pujol, J., Zhang, F.-M., Sun, H.-Q., Ying, T.-S. & Ge, S. 2011a. Centres of plant endemism in China: places for survival or for speciation? Journal of Biogeography 38: 1267–1280. http://dx.doi.org/10.1111/j.1365-2699.2011.02504.x; Wang et al., 2011Wang, Z., Fang, J., Tang, Z. & Lin, X. 2011. Patterns, determinants and models of woody plant diversity in China. Proceedings of the Royal Society, B, Biological Sciences 278: 2122–2132. http://dx.doi.org/10.1098/rspb.2010.1897; Huang et al., 2012Huang, J., Chen, B., Liu, C., Lai, J., Zhang, J. & Ma, K. 2012. Identifying hotspots of endemic woody seed plant diversity in China. Diversity and Distributions 18: 673–688. http://dx.doi.org/10.1111/j.1472-4642.2011.00845.x; Yang et al., 2013Yang, W., Ma, K. & Kreft, H. 2013. Geographical sampling bias in a large distributional database and its effects on species richness–environment models. Journal of Biogeography 40: 1415–1426. http://dx.doi.org/10.1111/jbi.12108).

Figure 1. Approximate location of Chinese plant diversity hotspots. The code numbers for the hotspots correspond to those in the table below the map. Relative occurrences for each type of plant species (+++, high occurrence; ++, intermediate occurrence; +, low occurrence) for each hotspot have been inferred after taking into account relevant literature (e.g. Ying et al., 1993Ying, T. S, Zhang, Y. L. & Boufford, D. E. 1993. The endemic genera of seed plants in China. Science Press, Beijing.; Wang & Zhang, 1994Wang, H.-S. & Zhang, Y.-L. 1994. 中国种子植物特有属的生物多样性和特征 [The bio-diversity and characters of spermatophytic genera endemic to China]. Acta Botanica Yunnanica 16: 209–220 [in Chinese].; Ying, 2001Ying, T.-S. 2001. 中国种子植物物种多样性及其分布格局 [Species diversity and distribution pattern of seed plant in China]. Biodiversity Science 9: 393–398 [in Chinese]. http://dx.doi.org/10.3321/j.issn:1005-0094.2001.04.011; Tang et al., 2006Tang, Z., Wang, Z., Zheng, C. & Fang, J. 2006. Biodiversity in China’s mountains. Frontiers in Ecology and the Environment 4: 347–352. http://dx.doi.org/10.1890/1540-9295(2006)004[0347:BICM]2.0.CO;2; Zhang & Ma, 2008Zhang, Y.-B. & Ma, K.-P. 2008. Geographic distribution patterns and status assessment of threatened plants in China. Biodiversity and Conservation 17: 1783–1798. http://dx.doi.org/10.1007/s10531-008-9384-6; Li et al., 2009Li, G., Shen, Z., Ying, T. & Fang, J. 2009. 中国裸子植物物种丰富度空间格局与多样性中心 [The spatial pattern of species richness and diversity centers of gymnosperm in China]. Biodiversity Science 17: 272–279 [in Chinese]. http://dx.doi.org/10.3724/SP.J.1003.2009.08327; López-Pujol et al., 2011aLópez-Pujol, J., Zhang, F.-M., Sun, H.-Q., Ying, T.-S. & Ge, S. 2011a. Centres of plant endemism in China: places for survival or for speciation? Journal of Biogeography 38: 1267–1280. http://dx.doi.org/10.1111/j.1365-2699.2011.02504.x; Wang et al., 2011Wang, Z., Fang, J., Tang, Z. & Lin, X. 2011. Patterns, determinants and models of woody plant diversity in China. Proceedings of the Royal Society, B, Biological Sciences 278: 2122–2132. http://dx.doi.org/10.1098/rspb.2010.1897; Huang et al., 2012Huang, J., Chen, B., Liu, C., Lai, J., Zhang, J. & Ma, K. 2012. Identifying hotspots of endemic woody seed plant diversity in China. Diversity and Distributions 18: 673–688. http://dx.doi.org/10.1111/j.1472-4642.2011.00845.x; Yang et al., 2013Yang, W., Ma, K. & Kreft, H. 2013. Geographical sampling bias in a large distributional database and its effects on species richness–environment models. Journal of Biogeography 40: 1415–1426. http://dx.doi.org/10.1111/jbi.12108). [View full size] [Descargar tamaño completo]

Besides the high taxonomic richness and exceptional rates of endemism, one of the main features of Chinese vascular flora is its ancient origin. China has a disproportionately large number of species belonging to the early diverged groups with ancient fossils; for example, the number of the pteridophytes and the gymnosperms are three times and almost two times larger in China than in the United States, respectively (Qian & Ricklefs, 1999Qian, H. & Ricklefs, R. E. 1999. A comparison of the taxonomic richness of vascular plants in China and the United States. The American Naturalist 154: 160–181. http://dx.doi.org/10.1086/303230), a country with a similar land area and a comparable floristic richness and composition until the Middle Miocene ca. 14–15 Ma (Axelrod et al., 1996Axelrod, D. I., Al-Shehbaz, I. & Raven, P. H. 1996. History of the modern flora of China. In: Zhang, A. & Wu, S (Eds.), Floristic characteristics and diversity of East Asian plants. China Higher Education Press, Beijing: 43–55. ). Likewise, there is also an overrepresentation of the basal groups of angiosperms, such as the magnolids and ranunculids within the Chinese flora (Qian & Ricklefs, 1999Qian, H. & Ricklefs, R. E. 1999. A comparison of the taxonomic richness of vascular plants in China and the United States. The American Naturalist 154: 160–181. http://dx.doi.org/10.1086/303230; Qian, 2001Qian, H. 2001. A comparison of generic endemism of vascular plants between East Asia and North America. International Journal of Plant Sciences 162: 191–199. http://dx.doi.org/10.1086/317909). Other empirical data supporting the antiquity of Chinese flora are the Tertiary origin of most of the ca. 1400 Asian endemic genera present in China (Qian et al., 2006Qian, H., Wang, S., He, J.-S., Zhang, J., Wang, L., Wang, X. & Guo, K. 2006. Phytogeographical analysis of seed plant genera in China. Annals of Botany 98: 1073–1084. http://dx.doi.org/10.1093/aob/mcl192), most of the ca. 250 Chinese endemic genera (Ying et al., 1993Ying, T. S, Zhang, Y. L. & Boufford, D. E. 1993. The endemic genera of seed plants in China. Science Press, Beijing.; Wu et al., 2007Wu, Z., Sun, H., Zhou, Z., Peng, H. & Li, D. 2007. Origin and differentiation of endemism in the flora of China. Frontiers of Biology in China 2: 125–143. http://dx.doi.org/10.1007/s11515-007-0020-8), and ca. 40% of the species belonging to the Chinese endemic genera (López-Pujol et al., 2011aLópez-Pujol, J., Zhang, F.-M., Sun, H.-Q., Ying, T.-S. & Ge, S. 2011a. Centres of plant endemism in China: places for survival or for speciation? Journal of Biogeography 38: 1267–1280. http://dx.doi.org/10.1111/j.1365-2699.2011.02504.x). Many lineages that were widely distributed along the Northern Hemisphere at the Miocene are still persisting in China, thanks to much lower extinction rates (Manchester et al., 2009Manchester, S. R., Chen, Z.-D., Lu, A.-M. & Uemura, K. 2009. Eastern Asian endemic seed plant genera and their paleogeographic history throughout the Northern Hemisphere. Journal of Systematics and Evolution 47: 1–42. http://dx.doi.org/10.1111/j.1759-6831.2009.00001.x). Conspicuous examples include Cathaya argyrophylla, Eucommia ulmoides, Ginkgo biloba, Glyptostrobus pensilis, Metasequoia glyptostroboides (Fig. 2), and Taiwania cryptomerioides. Notably, most of these palaeoendemic taxa tend to occur in central, south-central, and southeastern China (Fig. 1), regions that have generally enjoyed relative tectonic stability since the late Tertiary or earlier (Hsü, 1983Hsü, J. 1983. Late Cretaceous and Cenozoic vegetation in China, emphasizing their connections with North America. Annals of the Missouri Botanical Garden 70: 490–508. http://dx.doi.org/10.2307/2992084). At the same time, China harbours what is perhaps the largest “evolutionary front” of the world’s temperate flora, the Qinghai-Tibet Plateau (QTP), especially its eastern fringe (the Hengduan Mountains; Fig. 1). The continuous uplifts of the QTP, in particular the recent uplifts since the late Pliocene, may have created a vast array of new habitats across wide elevational ranges (up to 5000 m), therefore stimulating rapid plant diversification and speciation (Fig. 2), including allopatric speciation, hybrid speciation and explosive radiations (Liu et al., 2014Liu, J.-Q., Duan, Y.-W., Hao, G., Ge, X.-J. & Sun, H. 2014. Evolutionary history and underlying adaptation of alpine plants on the Qinghai–Tibet Plateau. Journal of Systematics and Evolution 52: 241–249. http://dx.doi.org/10.1111/jse.12094; Wen et al., 2014Wen, J., Zhang, J.-Q., Nie, Z.-L., Zhong, Y. & Sun, H. 2014. Evolutionary diversifications of plants on the Qinghai-Tibetan Plateau. Frontiers in Genetics 5: 4. http://dx.doi.org/10.3389/fgene.2014.00004; Favre et al., 2015Favre, A., Päckert, M., Pauls, S. U., Jähnig, S. C., Uhl, D., Michalak, I. & Muellner-Riehl, A. N. 2015. The role of the uplift of the Qinghai-Tibetan Plateau for the evolution of Tibetan biotas. Biological Reviews 90: 236–253. http://dx.doi.org/10.1111/brv.12107; Hugues & Atchison, 2015Hugues, C. E. & Atchison, G. W. 2015. The ubiquity of alpine plant radiations: from the Andes to the Hengduan Mountains. New Phytologist 207: 275–282. http://dx.doi.org/10.1111/nph.13230). Hengduan mountains have been internationally identified as one of the world’s biodiversity hotspots, with around 12,000 plant species, of which ~3500 are endemic (Myers et al., 2000Myers, N., Mittermeier, R. A., Mittermeier, C. G., da Fonseca, G. A. B. & Kent, J. 2000. Biodiversity hotspots for conservation priorities. Nature 403: 853–858. http://dx.doi.org/10.1038/35002501). Some alpine genera have their centres of distribution here, a result of the abovementioned rapid radiations; examples include Rhododendron (276 out of ~1000 species of this genus around the world are present in the Hengduan Mountains), Pedicularis (233 out of ~600), Primula (143 out of ~500), Gentiana (154 out of ~360), Saussurea (119 out of ~415), or Aconitum (108 out of ~400) (Zhang et al., 2009Zhang, D.-C., Zhang, Y.-H., Boufford, D. E. & Sun, H. 2009. Elevational patterns of species richness and endemism for some important taxa in the Hengduan Mountains, southwestern China. Biodiversity and Conservation 18: 699–716. http://dx.doi.org/10.1007/s10531-008-9534-x).

Figure 2. (A), type tree of Metasequoia glyptostroboides at Moudao Town (Hubei Province). This truly “living fossil” is a remnant of the Tertiary termophilous flora that once spanned most of the Northern Hemisphere (the “boreotropical flora”; Kubitzki & Krutzsch, 1996Kubitzki, K. & Krutzsch, W. 1996. Origins of East and South East Asian plant diversity. In: Zhang, A. & & Wu, S. (Eds.), Floristic characteristics and diversity of East Asian plants, China Higher Education Press, Beijing: 56–70.). Photograph: Q. Leng; (B), individual of Meconopsis integrifolia at Diqing Tibetan Autonomous Prefecture, NW Yunnan; this is one of the flagship species of the Qinghai-Tibetan Plateau, and its speciation probably occurred during the rapid uplift of the plateau at Pliocene–early Quaternary (Yang et al., 2012Yang, F.-S., Qin, A.-L., Li, Y.-F. & Wang, X.-Q. 2012. Great genetic differentiation among populations of Meconopsis integrifolia and its implication for plant speciation in the Qinghai-Tibetan Plateau. PLoS ONE 7: e37196. http://dx.doi.org/10.1371/journal.pone.0037196). Photograph: J. López-Pujol. [View full size] [Descargar tamaño completo]

Regrettably, the flora of China also stands out for the high number of threatened species, due to a series of combined factors mainly related with the country’s overpopulation, the economic growth [China has shown the fastest rate of GDP (gross domestic product) growth among the world’s major economies, with an average of almost 10% since 1980; http://data.worldbank.org/], the large-scale destruction of natural habitats, the over-exploitation of natural resources, and, on a lesser scale, the introduction of exotic species (although the lists of invasive and naturalized plant species have increased several-fold in just two decades; Fig. 3). At the beginning of the 2000s, it was estimated that at least 200 plant species had become extinct since the 1950s (Zhang et al., 2000Zhang, P., Shao, G., Zhao, G., Le Master, D. C., Parker, G. R., Dunning Jr., J. B. & Li, Q. 2000. China’s forest policy for the 21st century. Science 288: 2135–2136. http://dx.doi.org/10.1126/science.288.5474.2135), and new species have been added to this “black” list since then (see MEP–CAS, 2013MEP–CAS (Ministry of Environmental Protection–Chinese Academy of Sciences) 2013. 中国生物多样性红色名录 - 高等植物卷 - 评估报告 [China Red List of Higher Plants – Evaluation’s Report]. Ministry of Environmental Protection of the People’s Republic of China & Chinese Academy of Sciences, Beijing [in Chinese].). Many more species are in an extreme situation of risk, with population sizes of fewer that one hundred individuals and occurring in just one or very few populations (e.g. López-Pujol & Zhang, 2009López-Pujol, J. & Zhang, Z.-Y. 2009. An insight into the most threatened flora of China. Collectanea Botanica 28: 95–110. http://dx.doi.org/10.3989/collectbot.2008.v28.004; López-Pujol, 2010López-Pujol, J. 2010. China: home for the most endangered plant species of the world? Collectanea Botanica 29: 99–101. http://dx.doi.org/10.3989/collectbot.2010.v29.010; Ren et al, 2012Ren, H., Zhang, Q., Lu, H. et al. 2012. Wild plant species with extremely small populations require conservation and reintroduction in China. Ambio 41: 913–917. http://dx.doi.org/10.1007/s13280-012-0284-3; Ma et al., 2013Ma, Y., Chen, G., Grumbine, R. E., Dao, Z., Sun, W. & Guo, H. 2013. Conserving plant species with extremely small populations (PSESP) in China. Biodiversity and Conservation 22: 803–809. http://dx.doi.org/10.1007/s10531-013-0434-3); examples of these species in the brink of extinction [called sometimes as “Extremely Narrow Endemics” (ENE) or “Plant Species with Extremely Small Populations” (PSESP); cf. López-Pujol et al., 2013López-Pujol, J., Martinell, M. C., Massó, S., Blanché, C. & Sáez, L. 2013. The ‘paradigm of extremes’: Extremely low genetic diversity in an extremely narrow endemic species, Coristospermum huteri (Umbelliferae). Plant Systematics and Evolution 299: 439–446. http://dx.doi.org/10.1007/s00606-012-0732-3; Ma et al., 2013Ma, Y., Chen, G., Grumbine, R. E., Dao, Z., Sun, W. & Guo, H. 2013. Conserving plant species with extremely small populations (PSESP) in China. Biodiversity and Conservation 22: 803–809. http://dx.doi.org/10.1007/s10531-013-0434-3] include Abies beshanzuensis var. beshanzuensis (from which only three individuals are remaining in the wild), Acer yangbiense (four individuals), and Carpinus putoensis (only one individual). According to the China Red List of Higher Plants (中国生物多样性红色名录-高等植物卷), published in late 2013, 3650 vascular plant taxa were regarded as threatened (CR, EN, or VU) following the 2001 IUCN criteria among the ~33,000 evaluated taxa (MEP–CAS, 2013MEP–CAS (Ministry of Environmental Protection–Chinese Academy of Sciences) 2013. 中国生物多样性红色名录 - 高等植物卷 - 评估报告 [China Red List of Higher Plants – Evaluation’s Report]. Ministry of Environmental Protection of the People’s Republic of China & Chinese Academy of Sciences, Beijing [in Chinese].). The number of threatened plant species in China is, thus, slightly lower than the “classical” estimations of 4000–5000 (Wang, 1992Wang, S. (Ed.) 1992. Biodiversity in China: status and conservation needs. Science Press, Beijing & New York.; López-Pujol et al., 2006López-Pujol, J., Zhang, F.-M. & Ge, S. 2006. Plant biodiversity in China: richly varied, endangered and in need of conservation. Biodiversity and Conservation 15: 3983–4026. http://dx.doi.org/10.1007/s10531-005-3015-2; Huang & Oldfield, 2015Huang, H.-W. & Oldfield, S. 2015. The extinction crisis. In: Hong, D.-Y. & Blackmore, S. (Eds.), Plants of China – A companion to the Flora of China. Science Press, Beijing: 407–417. ), although it should be taken into account that more than 4000 taxa were listed as “Data Deficient” (DD) in the 2013 Red List: an important fraction of these 4000 taxa, once a better knowledge is achieved, could be transferred to any of the threatened categories. Endangered species tend to be concentrated in the southern part of the country (Zhang & Ma, 2008Zhang, Y.-B. & Ma, K.-P. 2008. Geographic distribution patterns and status assessment of threatened plants in China. Biodiversity and Conservation 17: 1783–1798. http://dx.doi.org/10.1007/s10531-008-9384-6), thus showing high congruence with both centres of species richness and endemism (Fig. 1).

Figure 3. Construction of the Chengdu–Lanzhou high-speed railway. May 2015, Aba Prefecture, Sichuan. The first line of high-speed railway was completed in 2007, and the network reached 16,000 km at the end of 2014 (Xinhua, 2015Xinhua 2015. China boasts world’s largest highspeed railway network. Xinhua Agency News, January 30, 2015. Retrieved Accessed October 6, 2015, from http://news.xinhuanet.com/english/photo/2015-01/30/c_133959250.htm). Construction of transportation corridors such as railways do not only cause habitat fragmentation (and the associated edge-effects) but also the spread and establishment of non-native species (Andrews, 1990Andrews, A. 1990. Fragmentation of habitat by roads and utility corridors: a review. Australian Zoologist 26: 130–141. http://dx.doi.org/10.7882/AZ.1990.005; Hansen & Clevenger, 2005Hansen, M. J. & Clevenger, A. P. 2005. The influence of disturbance and habitat on the presence of non-native plant species along transport corridors. Biological Conservation 125: 249–259. http://dx.doi.org/10.1016/j.biocon.2005.03.024). Photograph: J. López-Pujol. [View full size] [Descargar tamaño completo]

Despite the unquestionable interest, the study of the Chinese flora has been systematically neglected by south European botanists, and particularly by the Spanish ones. These latter have traditionally been more concerned with the flora of the New World. The discovery and further colonization of most of the Americas by the Spaniards was followed by the study of their flora (e.g. Álvarez, 1993Álvarez, R. 1993. La conquista de la naturaleza americana (Cuadernos Galileo de Historia de la Ciencia, 14). Consejo Superior de Investigaciones Científicas, Madrid.; De Vos, 2007De Vos, P. S. 2007 Natural history and the pursuit of empire in eighteenth-century Spain. Eighteenth-Century Studies 40: 209–239. http://dx.doi.org/10.1353/ecs.2007.0003), which has continued to the present. A variation of this sort of “colonial botany” (cf. Schiebinger & Swan, 2005Schiebinger, L. & Swan, C. (Eds.) 2005. Colonial botany: Science, commerce, and politics in the early modern world. University of Pennsylvania Press, Philadelphia.) was behind bringing many Chinese plants to the West (including many ornamental plants such as azaleas, lilies, and magnolias) by European missionaries following the Opium Wars (mid-19th century). Today, many plants are named for some of these “priests-botanists” (the most illustrious are probably J. M. Delavay, A. David, and P. G. Farges; see Kilpatrick, 2014Kilpatrick, J. 2014. Fathers of botany – The discovery of Chinese plants by European missionaries. University of Chicago Press, Chicago.). During late 19^th–early 20^th century, the European missionaries were gradually replaced mainly by British/Irish (such as G. Forrest, A. Henry, F. Kingdon-Ward, and E. H. Wilson), Austrian (H. von Handel-Mazzetti and J. Rock), and Russian plant explorers (E. Bretschneider and G. N. Potanin), as well as the “first generation” of Chinese botanists (e.g. W.-C. Cheng, R.-C. Ching, W.-P. Fang, and T.-T. Yü) (Hi & Watson, 2015Hi, C.-M. & Watson, M. F. 2015. Plant exploration in China: In: Hong, D.-Y. & Blackmore, S. (Eds.), Plants of China – A companion to the Flora of China. Science Press, Beijing: 212–236.). After the advent of the “open door” policy in China since late 1970s, collaboration between Chinese and foreign botanists (especially with the American ones) is increasing steadily. The recent completion of the Flora of China project (partly funded by the U.S. National Science Foundation) is probably the best example.

This special issue of Collectanea Botanica, which corresponds to volume 34, has been launched not only for contributing to the knowledge of Chinese flora but also as an effort to increase the collaboration between Spanish and Chinese botanists, which remains, in spite of the pioneering efforts of the authors of the present note, virtually nil. This is not an isolated case, unfortunately, and certainly reflects the narrow-mindedness of the Spanish science system. The last official report on the Spanish scientific activity (FECYT, 2014FECYT (Fundación Española para la Ciencia y la Tecnología) 2014. Indicadores bibliométricos de la actividad científica española 2011. Publicación 2014. Fundación Española para la Ciencia y la Tecnología, Alcobendas. ) placed China, which is already the second-largest producer of research papers in the world (after the United States), “only” the 24^th in the rank of scientific collaborations between Spain and a third country (for example, behind Greece, Poland, and Chile).

This special issue is composed by eight articles (seven full-length articles and one short note) addressing several topics such as biogeography, conservation, demography, ecology, evolution, and plant-animal relations. Three of the contributions, those of Liao & Ren (2015Liao, H.-Y. & Ren, M.-X. 2015. Distribution patterns of long-lived individuals of relict plants around Fanjingshan Mountain in China: Implications for in situ conservation. Collectanea Botanica 34: e002. http://dx.doi.org/10.3989/collectbot.2015.v34.002), Ren (2015Ren, M.-X. 2015. The upper reaches of the largest river in Southern China as an “evolutionary front” of tropical plants: Evidences from Asia-endemic genus Hiptage (Malpighiaceae). Collectanea Botanica 34: e003. http://dx.doi.org/10.3989/collectbot.2015.v34.003), and Hu et al. (2015Hu, X.-Y., Zhu, J., Song, X.-Q. & He, R.-X. 2015. Orchid diversity in China’s Hainan Island: Distribution and conservation. Collectanea Botanica 34: e007. http://dx.doi.org/10.3989/collectbot.2015.v34.007) are centred on some of the main hotspots of Chinese flora (Fig. 1). Liao & Ren (2015Liao, H.-Y. & Ren, M.-X. 2015. Distribution patterns of long-lived individuals of relict plants around Fanjingshan Mountain in China: Implications for in situ conservation. Collectanea Botanica 34: e002. http://dx.doi.org/10.3989/collectbot.2015.v34.002) explored the distribution patterns of long-lived individuals (≥100 years old) of several relict species (Cyclocarya paliurus, Ginkgo biloba, Liriodendron chinense, Pinus massoniana, Podocarpus macrophyllus, and Taxus chinensis) in the areas surrounding Fanjinshan Nature Reserve, located in the central China Mountains hotspot (probably the most important in China in terms of relict species; López-Pujol & Ren, 2010López-Pujol, J. & Ren, M.-X. 2010. China: a hot spot of relict plant taxa. In: Rescigno, V. & Maletta, S. (Eds.), Biodiversity hotspots. Nova Science Publishers, New York: 123–137.; López-Pujol et al., 2011bLópez-Pujol, J., Zhang, F.-M., Sun, H.-Q., Ying, T.-S. & Ge, S. 2011b. Mountains of southern China as ‘plant museums’ and ‘plant cradles’: evolutionary and conservation insights. Mountain Research and Development 31: 261–269. http://dx.doi.org/10.1659/MRD-JOURNAL-D-11-00058.1). The authors conclude that, as reported in other studies (e.g. Hu et al., 2011Hu, L., Li, Z., Liao, W.-B. & Fan, Q. 2011. Values of village fengshui forest patches in biodiversity conservation in the Pearl River Delta, China. Biological Conservation 144: 1553–1559. http://dx.doi.org/10.1016/j.biocon.2011.01.023; Gao et al., 2013Gao, H., Ouyang, Z., Chen, S. & van Koppen, C. S. A. 2013. Role of culturally protected forests in biodiversity conservation in Southeast China. Biodiversity and Conservation 22: 531–544. http://dx.doi.org/10.1007/s10531-012-0427-7), local protection due to traditional beliefs would have also played a role in addition to the existence of long-term stable habitats (see also Huang et al., 2015bHuang, Y., Jacques, F. M. B., Su, T., Ferguson, D. K., Tang, H., Chen, W. & Zhou, Z. 2015b. Distribution of Cenozoic plant relicts in China explained by drought in dry season. Scientific Reports 5: 14212. http://dx.doi.org/10.1038/srep14212). Ren (2015Ren, M.-X. 2015. The upper reaches of the largest river in Southern China as an “evolutionary front” of tropical plants: Evidences from Asia-endemic genus Hiptage (Malpighiaceae). Collectanea Botanica 34: e003. http://dx.doi.org/10.3989/collectbot.2015.v34.003) focused in another biodiversity hotspot, SE Yunnan–SW Guizhou–SW Guangxi (Fig. 1). He used distributional data of ca. 30 species belonging to the genus Hiptage to find that this region is a major diversification centre of this Asian endemic genus. Since other studies reported similar results for other tropical families including Gesneriaceae and Begoniaceae (Li & Wang, 2004Li, Z. Y. & Wang, Y. Z. 2004. 中国苦苣苔科植物 [Gesneriaceae of China]. Henan Scientific and Technical Publishing House, Zhengzhou [in Chinese].; Wei et al., 2004Wei, Y.-G., Zhong, S.-H. & Wen, H.-Q. 2004. 广西苦苣苔科植物区系和生态特点研究 [Studies on the flora and ecology of Gesneriaceae in Guangxi Province]. Acta Botanica Yunnanica 26: 173–182 [in Chinese].; Hou et al., 2010Hou, M., López-Pujol, J., Qin, H.-N., Wang, L.-S. & Liu, Y. 2010. Distribution pattern and conservation priorities for vascular plants in Southern China: Guangxi Province as a case study. Botanical Studies 51: 377–386.), it does not seem unreasonable to define this area (which is dominated by highly-fragmented limestone landscapes) as the “evolutionary front of the tropical plants in China” Ren, 2015Ren, M.-X. 2015. The upper reaches of the largest river in Southern China as an “evolutionary front” of tropical plants: Evidences from Asia-endemic genus Hiptage (Malpighiaceae). Collectanea Botanica 34: e003. http://dx.doi.org/10.3989/collectbot.2015.v34.003: 9). Hainan is also one of the main hotspots of plant diversity in China (Fig. 1), and it is the subject of the studied carried out by Hu et al. (2015Hu, X.-Y., Zhu, J., Song, X.-Q. & He, R.-X. 2015. Orchid diversity in China’s Hainan Island: Distribution and conservation. Collectanea Botanica 34: e007. http://dx.doi.org/10.3989/collectbot.2015.v34.007). The authors analysed the diversity and the patterns of distribution of the Orchidaceae [the fourth largest family in China in number of species, but the first regarding the number of endangered species (ca. 670 are included in any of the threatened categories; MEP–CAS, 2013MEP–CAS (Ministry of Environmental Protection–Chinese Academy of Sciences) 2013. 中国生物多样性红色名录 - 高等植物卷 - 评估报告 [China Red List of Higher Plants – Evaluation’s Report]. Ministry of Environmental Protection of the People’s Republic of China & Chinese Academy of Sciences, Beijing [in Chinese].)] in Hainan Island, identifying over 300 species (with ~10% of them endemic) that mainly occur on the southern part of the island. Hu et al. (2015Hu, X.-Y., Zhu, J., Song, X.-Q. & He, R.-X. 2015. Orchid diversity in China’s Hainan Island: Distribution and conservation. Collectanea Botanica 34: e007. http://dx.doi.org/10.3989/collectbot.2015.v34.007) also revised the threats and the current conservation status of Hainan’s orchids, and proposed future directions for research and management.

Although not strictly focused on the Chinese biodiversity hotspots, two additional papers within this special issue deal with biogeographical and ecological aspects within the topographically-complex, floristically-rich subtropical China. Tang (2015Tang, C. Q. 2015. Distribution patterns of the subtropical evergreen broad-leaved forests of southwestern China, as compared with those of the eastern Chinese subtropical regions. Collectanea Botanica 34: e006. http://dx.doi.org/10.3989/collectbot.2015.v34.006) presented an exhaustive analysis of the geographic distribution patterns of subtropical evergreen broad-leaved forests (EBLFs) in southwestern China (Guizhou, Sichuan, and Yunnan provinces plus Chongqing Municipality). In addition to comprehensively review the EBLFs in terms of forest types, species composition, and their distributions along latitudinal, longitudinal, and altitudinal gradients (which are magnificently illustrated), the author compared them with those of eastern China (with a special emphasis on Taiwan Island). Wang et al. (2015aWang, H.-F., Ren, M.-X., López-Pujol, J., Ross Friedman, C., Fraser, L. H. & Huang, G.-X. 2015a. Plant species and communities in Poyang Lake, the largest freshwater lake in China. Collectanea Botanica 34: e004. http://dx.doi.org/10.3989/collectbot.2015.v34.004) focused, instead, on aquatic habitats, and used traditional vegetation surveying methods to assess the richness of plant species and communities in Poyang Lake. This lake, the largest one in China, has gained notoriety for the dam that has been planned to stabilize its water level (due to a series of droughts in recent years), causing serious concerns among biologists and conservationists (Li, 2009Li, J. 2009. Scientists line up against dam that would alter protected wetlands. Science 236: 508–509. http://dx.doi.org/10.1126/science.326_508). Wang et al. (2015aWang, H.-F., Ren, M.-X., López-Pujol, J., Ross Friedman, C., Fraser, L. H. & Huang, G.-X. 2015a. Plant species and communities in Poyang Lake, the largest freshwater lake in China. Collectanea Botanica 34: e004. http://dx.doi.org/10.3989/collectbot.2015.v34.004) identified over 500 plant species (as a catalogue in a separate appendix) as well as eight dominant plant communities, confirming the lake’s wetland as a regional hotspot.

Liu et al. (2015Liu, W.-H., Dai, X.-H. & Xu, J.-S. 2015. Influences of leaf-mining insects on their host plants: A review. Collectanea Botanica 34: e005. http://dx.doi.org/10.3989/collectbot.2015.v34.005) presented the state-of-the-art in the interactions between leaf miners (those insects whose larvae live in and eat the leaf tissue of plants) and their host plants. The authors first reviewed the leaf-mining patterns on plant leaves (i.e. the diversity of leaf mine shapes and depths). Next, they addressed impacts in leaf morphology (e.g. asymmetry, presence of holes and cracks), leaf chemistry (e.g. production of secondary metabolites, formation of callus tissue), plant physiology (typically, a reduction of the photosynthetic capability of the leaf), and plant growth and production (e.g. earlier fall of the leaves, lower plant height, smaller leave size, lower number of leaves, reduction in fruit set). The authors further summarized the studies of leaf miners carried out in China. A further paper in this special issue is a mini-review of the main results of almost one-decade research carried by H. F. Wang and his collaborators on urban vegetation and plant diversity in Beijing, the capital of China. In their mini-review, Wang & López-Pujol (2015Wang, H.-F & López-Pujol, J. 2015. Urban green spaces and plant diversity at different spatial–temporal scales: A case study from Beijing, China. Collectanea Botanica 34: e008. http://dx.doi.org/10.3989/collectbot.2015.v34.008) first presented the main results of a study that employed urban structural units (USUs, that were defined based on urban land use and land cover) to explore urban ecological patterns and their relation with socio-economic factors. At the species level instead of landscape level, the authors reported the results of a systematic investigation on the plant species richness and density and the main socio-economic factors affecting them. They also summarized the naturalized and invasive flora in the whole municipality. This special issue was closed by a short note dealing with a growing menace for plant diversity in China: the plant invasions. Wang et al. (2015cWang, Z.-Q., Guillot, D. & López-Pujol, J. 2015c. Crassula ovata, a new alien plant for mainland China. Collectanea Botanica 34: e009. http://dx.doi.org/10.3989/collectbot.2015.v34.009) reported the first occurrence of Crassula ovata, the jade plant, in China, and warned about the potential for naturalization of this plant, as it is widely cultivated (at least in Sichuan, the province where it has been observed).

REFERENCESTop