Forest characteristics and population structure of Glyptostrobus pensilis, a globally endangered relict species of southeastern China

Abstract

The Chinese water pine Glyptostrobus pensilis is the sole surviving species of the genus Glyptostrobus. It is endemic to southern China, central Vietnam, and eastern Laos, and today it is nearly extinct in the wild. Forest community characteristics and population structure of G. pensilis in China have remained unknown up to now. We investigated six swamp forest stands and analyzed their forest community characteristics (i.e. vertical stratification, species composition, and diversity) and population structure, including the frequency distribution of DBH (diameter at breast height) and age-classes as found in Fujian Province, southeastern China.The vertical stratifications of all the forest stands were rather simple. The remaining wild specimens ranged from roughly 15 to some 357 years for an average of ca. 85 years, with only a few individuals less than 20 years old. Compared with the stands and populations of G. pensilis in Vietnam, the taxonomic compositions of the stands in the two regions were different, except for the dominant species-G. pensilis. The Shannon–Wiener index showed the overstory of each stand had much lower diversity (0.26 on average) in Fujian Province than that (1.97 on average) in Vietnam, whereas the diversity indices were about the same (around 2.41) for the understories in the two regions. Furthermore, we discovered 18 G. pensilis seedlings at the study sites in Fujian Province. This discovery demonstrates that G. pensilis regeneration is extremely poor and its populations are declining, although these populations are relatively healthier than those in Vietnam.

Prediction of Suitable Distribution of a Critically Endangered Plant Glyptostrobus pensilis

“…From 2004 to 2019, Our team (include Bao Liu, Shi pin Chen, Shi-qun Zheng, Shaoning Ruan, Tian-yu Zhang and Xing-zhuang Ye) conducted field investigations of the natural population of G. pensilis in Fujian, Jiangxi and Guangdong provinces and collected 24 distribution records [39,40,42]. The published literature was reviewed to collect 9 and 5 records of the population distribution of G. pensilis in Vietnam and Laos, respectively [29,31,34,36,43]. 41 distribution records were collected by consulting the published literature; retrieval of global biodiversity information facility (http://www.gbif.…”

“…After the Younger Dryas (about 12.5-11.5 kaBP) event, a large number of marshlands appeared in Fujian, which was particularly suitable for the habitat requirements of G. pensilis [57,61]. Rare populations of G. pensilis were found in Youxi County, Pingnan County and Zhouning County of Fujian Province and it was scattered in more than 20 counties of Fujian province (Figure S10) [30,32,34,39,42]. Therefore, it was reasonable and credible for MaxEnt to predict that the highly suitable habitats of G. pensilis during the LIG and the LGM is mainly located in Fujian Province.…”

“…In recent years, the distribution area of G. pensilis has been shrinking and the habitat fragmentation has become increasingly serious, for example, before the 1950s it was a common species in the Pearl River Delta, but now there are only 14 individuals in eight populations in Guangzhou [33]. Except for a few places such as Youxi in Fujian, Shanglou in Pingnan County and Yiyang in Jiangxi, it is difficult to observe natural G. pensilis forests in other places and most of them are sporadically distributed (Figure S1) [34]. It is not only an important part of the phylogenetic research of Taxodiaceae plants but also a popular ornamental plant and a common tree species for windbreak and embankment reinforcement; it is also a good raw material for shipbuilding and bridge construction [31][32][33][34][35].…”

“…Except for a few places such as Youxi in Fujian, Shanglou in Pingnan County and Yiyang in Jiangxi, it is difficult to observe natural G. pensilis forests in other places and most of them are sporadically distributed (Figure S1) [34]. It is not only an important part of the phylogenetic research of Taxodiaceae plants but also a popular ornamental plant and a common tree species for windbreak and embankment reinforcement; it is also a good raw material for shipbuilding and bridge construction [31][32][33][34][35]. The secondary metabolites of G. pensilis bark can also inhibit the activity of human protein tyrosine phosphatase [36].…”

“…Therefore, protecting and expanding its remaining habitat and increasing its population size are the most important measures to protect G. pensilis [29]. At present, there are few studies on G. pensilis, most of which focus on population dynamics, physiological ecology, reproductive biology and genetic diversity [27][28][29][30][31][32][33][34][35][36][38][39][40]. However, none of the above studies has carried out an in-depth study on the relationship between climate factors and the distribution pattern of G. pensilis.…”