'Secondary hemiepiphytes' - A concept under scrutiny

“次生半附生植物”——一个正在接受审查的概念

• 批准号: 403244543
• 负责人: Professor Dr. Gerhard Zotz
• 金额: --
• 依托单位: Arbeitsgruppe Funktionelle Ökologie der Pflanzen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/403244543?language=en
• 关键词: Secondary; hemiepiphytes; concept; under; scrutiny

Tropical plant biodiversity is not only impressive in terms of species numbers, but also in terms of structural and life form diversity. Much of the complexity and diversity of a tropical forest is due to the occurrence of life forms that are quite rare or even altogether absent in temperate forests, e.g. vascular epiphytes, strangling or non-strangling hemiepiphytes, or woody and non-woody climbing plants, but the ecology of these groups is still little understood. A case in point are so-called ‘secondary hemiepiphytes’ (SH), plants defined by germination on the ground, ascent on tree trunks and dieback of the lower portion of the stem leading to severance of all connections with the ground. Although modern text books on tropical forest ecology typically describe SH as one of five mechanically dependent plant groups, the concept of ‘secondary hemiepiphyte’ is almost entirely based on anecdotal evidence. The few published experimental reports and own preliminary data suggest that plants categorized as SH do not lose connection with the soil, but rather that adventitious roots replace stems as water conducting systems. This could simply be a consequence of hydraulic limitations in climbers that lack secondary growth: almost all so-called SH are monocots. The proposed study will now rigorously address a problem that has been neglected both by liana researchers and epiphyte researchers. Based on a solid quantitative spatio-temporal analysis of SH communities in two tropical forests with a thorough census of root connections, we will investigate germination, establishment, and important functional aspects of SHs as compared to ‘normal’ vines and epiphytes. If we can show that all studied SH continuously depend on soil root contact, the entire notion of SH is probably blurs biological reality and the term secondary hemi-‘epiphyte’ is an unnecessary and even misleading misnomer. Alternatively, validating Kress´ notion for at least a few species would be evidence for an exciting facet of plant growth strategies.

热带植物的生物多样性不仅在物种数量方面令人印象深刻，而且在结构和生活形式多样性方面也令人印象深刻。热带森林的复杂性和多样性大部分是由于温带森林中非常罕见甚至完全不存在的生命形式的出现，例如维管附生植物，扼杀或非扼杀半附生植物，或木本和非木本攀缘植物，但这些群体的生态学仍然知之甚少。一个恰当的例子是所谓的“次生半附生植物”（SH），植物的定义是在地面上发芽，在树干上上升，茎的下部枯死，导致与地面的所有连接中断。虽然现代热带森林生态学教科书通常将SH描述为五个机械依赖植物群之一，但“次生半附生植物”的概念几乎完全基于轶事证据。少数发表的实验报告和自己的初步数据表明，被归类为SH的植物不会失去与土壤的联系，而是不定根取代茎作为水分传导系统。这可能仅仅是缺乏二次生长的攀缘植物的水力限制的结果：几乎所有所谓的SH都是单子叶植物。这项拟议中的研究现在将严格解决一个被藤本植物研究人员和真菌研究人员忽视的问题。一个坚实的定量时空分析SH社区在两个热带森林的根连接的彻底普查的基础上，我们将调查发芽，建立，和重要的功能方面的SH相比，“正常”的藤蔓和附生植物。如果我们能证明所有研究的SH持续依赖于土壤根接触，SH的整个概念可能是模糊的生物现实和术语次生半“附生植物”是一个不必要的，甚至误导用词不当。或者，至少在几个物种上验证克雷斯的概念将是植物生长策略令人兴奋的一个方面的证据。