Schwerbrock R, Leuschner C
Albrecht-von-Haller Institute for Plant Sciences, Plant Ecology and Ecosystems Research, University of Goettingen, Goettingen, Germany.
Plant Biol (Stuttg). 2016 Jul;18(4):649-57. doi: 10.1111/plb.12444. Epub 2016 Mar 7.
(1) Most ferns are restricted to moist and shady habitats, but it is not known whether soil moisture or atmospheric water status are decisive limiting factors, or if both are equally important. (2) Using the rare temperate woodland fern Polystichum braunii, we conducted a three-factorial climate chamber experiment (soil moisture (SM) × air humidity (RH) × air temperature (T)) to test the hypotheses that: (i) atmospheric water status (RH) exerts a similarly large influence on the fern's biology as soil moisture, and (ii) both a reduction in RH and an increase in air temperature reduce vigour and growth. (3) Nine of 11 morphological, physiological and growth-related traits were significantly influenced by an increase in RH from 65% to 95%, leading to higher leaf conductance, increased above- and belowground productivity, higher fertility, more epidermal trichomes and fewer leaf deformities under high air humidity. In contrast, soil moisture variation (from 66% to 70% in the moist to ca. 42% in the dry treatment) influenced only one trait (specific leaf area), and temperature variation (15 °C versus 19 °C during daytime) only three traits (leaf conductance, root/shoot ratio, specific leaf area); RH was the only factor affecting productivity. (4) This study is the first experimental proof for a soil moisture-independent air humidity effect on the growth of terrestrial woodland ferns. P. braunii appears to be an air humidity hygrophyte that, whithin the range of realistic environmental conditions set in this study, suffers more from a reduction in RH than in soil moisture. A climate warming-related increase in summer temperatures, however, seems not to directly threaten this endangered species.
（1）大多数蕨类植物局限于潮湿和阴凉的栖息地，但尚不清楚土壤湿度或大气水分状况是否是决定性的限制因素，或者两者是否同样重要。（2）我们利用珍稀的温带林地蕨类植物布朗耳蕨开展了一项三因素气候箱实验（土壤湿度（SM）×空气湿度（RH）×气温（T）），以检验以下假设：（i）大气水分状况（RH）对蕨类植物生物学的影响与土壤湿度相似，（ii）RH降低和气温升高都会降低活力和生长。（3）将RH从65%提高到95%，对11个形态、生理和生长相关性状中的9个产生了显著影响，导致在高气湿度下叶片导度更高、地上和地下生产力增加、繁殖力更高、表皮毛更多且叶片畸形更少。相比之下，土壤湿度变化（从潮湿处理中的66%至70%到干旱处理中的约42%）仅影响一个性状（比叶面积），而温度变化（白天15℃对19℃）仅影响三个性状（叶片导度、根/茎比、比叶面积）；RH是影响生产力的唯一因素。（4）本研究首次通过实验证明了大气湿度对陆生林地蕨类植物生长的影响与土壤湿度无关。布朗耳蕨似乎是一种空气湿度湿生植物，在本研究设定的实际环境条件范围内，其受RH降低的影响比土壤湿度降低的影响更大。然而，与气候变暖相关的夏季气温升高似乎不会直接威胁到这种濒危物种。
