Monro Alexandre K, Bystriakova Nadia, Fu Longfei, Wen Fang, Wei Yigang
Herbarium, Royal Botanic Gardens, Kew, London, United Kingdom.
IUCN Cave Invertebrate Specialist Group, Gland, Switzerland.
PLoS One. 2018 Feb 7;13(2):e0190801. doi: 10.1371/journal.pone.0190801. eCollection 2018.
Few studies document plants in caves. Our field observations of a widespread and seemingly angiosperm-rich cave flora in SW China lead us to test the following hypotheses, 1) SW China caves contain a diverse vascular plant flora, 2) that this is a relic of a largely absent forest type lacking endemic species, and 3) that the light environment plants occupy in caves is not distinct from non-cave habitats. To do so we surveyed 61 caves and used species accumulation curves (SAC) to estimate the total diversity of this flora and used a subsample of 14 caves to characterise the light environment. We used regional floras and existing conservation assessments to evaluate the conservation value of this flora. We used observations on human disturbance within caves to evaluate anthropogenic activities. Four-hundred-and-eighteen vascular plant species were documented with SACs predicting a total diversity of 529-846. Ninety-three percent of the species documented are known karst forest species, 7% are endemic to caves and 81% of the species are angiosperms. We demonstrate that the light environment in caves is distinct to that of terrestrial habitats and that a subset of the flora likely grow in the lowest light levels documented for vascularised plants. Our results suggest that the proportion of species threatened with extinction is like that for the terrestrial habitat and that almost half of the entrance caverns sampled showed signs of human disturbance. We believe that this is the first time that such an extensive sample of cave flora has been undertaken and that such a diverse vascular plant flora has been observed in caves which we predict occurs elsewhere in SE Asia. We argue that the cave flora is an extension of the karst forest understory present prior to catastrophic deforestation in the 20thC. We suggest that within SW China caves serve as both refuges and a valuable source of germplasm for the restoration of karst forest. We also propose that caves represent a distinct habitat for plants that is most similar to that of the forest understory, but distinct with respect to the absence of trees, leaf litter, root mats, higher levels of atmospheric CO2, and lower diurnal and annual variation in temperature and humidity. We highlight tourism, agriculture and the absence of legislated protection of caves as the main current threats to this flora.
很少有研究记录洞穴中的植物。我们在中国西南部对广泛分布且看似被子植物丰富的洞穴植物群进行了实地观察，这促使我们检验以下假设：1）中国西南部的洞穴中存在多样化的维管植物群；2）这是一种在很大程度上已不存在的森林类型的遗迹，且缺乏特有物种；3）洞穴中植物所处的光照环境与非洞穴栖息地并无明显差异。为此，我们调查了61个洞穴，并使用物种累积曲线（SAC）来估计该植物群的总多样性，还利用14个洞穴的子样本对光照环境进行了特征描述。我们使用区域植物志和现有的保护评估来评估该植物群的保护价值。我们通过对洞穴内人类干扰的观察来评估人为活动。共记录了418种维管植物，物种累积曲线预测总多样性为529 - 846种。记录的物种中有93%是已知的喀斯特森林物种，7%是洞穴特有物种，81%是被子植物。我们证明洞穴中的光照环境与陆地栖息地不同，并且该植物群的一部分可能生长在维管植物记录到的最低光照水平下。我们的结果表明，受灭绝威胁的物种比例与陆地栖息地相似，并且所采样的近一半洞口洞穴显示出人类干扰的迹象。我们认为这是首次对如此广泛的洞穴植物群样本进行研究，并且在洞穴中观察到了如此多样的维管植物群，我们预计在东南亚其他地方也会出现这种情况。我们认为洞穴植物群是20世纪灾难性森林砍伐之前存在的喀斯特森林林下植被的延伸。我们建议在中国西南部，洞穴既是避难所，也是恢复喀斯特森林的宝贵种质资源来源。我们还提出，洞穴代表了一种独特的植物栖息地，它与森林林下植被最为相似，但在没有树木、落叶层、根垫、大气中二氧化碳含量较高以及温度和湿度的昼夜和年度变化较小方面有所不同。我们强调旅游、农业以及缺乏对洞穴的立法保护是目前对该植物群的主要威胁。
