Bond-Lamberty Ben, Gower Stith T
Department of Forest Ecology and Management, University of Wisconsin, 1630 Linden Drive, Madison, WI 53706, USA.
Oecologia. 2007 Apr;151(4):584-92. doi: 10.1007/s00442-006-0619-5. Epub 2006 Dec 12.
Bryophytes dominate the carbon and nitrogen cycling of many poorly drained terrestrial ecosystems and are important in the vegetation-atmosphere exchange of carbon and water, yet few studies have estimated their leaf area at the stand scale. This study quantified the bryophyte-specific leaf area (SLA) and leaf area index (LAI) in a group of different-aged boreal forest stands in well and poorly drained soils. Species-specific SLA (for three feather mosses, four Sphagnum spp. and Aulacomnium palustre mixed with Tomentypnum nitens) was assessed by determining the projected area using a flatbed scanner and cross-sectional geometry using a dissecting microscope. The hemisurface leaf area was computed as the product of SLA and live biomass and was scaled by coverage data collected at all stands. Pleurozium schreberi dominated the spatial coverage, biomass and leaf area in the well-drained stands, particularly the oldest, while S. fuscum and A. palustre were important in the poorly drained stands. Live moss biomass ranged from 47 to 230 g m(-2) in the well-drained stands dominated by feather mosses and from 102 to 228 g m(-2) in the poorly drained stands. Bryophyte SLA varied between 135 and 473 cm(2) g(-1), for A. palustre and S. capillifolium, respectively. SLA was strongly and significantly affected by bryophyte species, but did not vary between stands; in general, there was no significant difference between the SLA of non-Sphagnum mosses. Bryophyte LAI increased with stand age, peaking at 3.1 and 3.7 in the well and poorly drained stands, respectively; this represented approximately 40% of the overstory LAI in the well-drained stands and 100-1,000% in the poorly drained stands, underscoring the important role bryophytes play in the water and carbon budgets of these boreal forests.
苔藓植物在许多排水不良的陆地生态系统的碳和氮循环中占主导地位,并且在植被与大气之间的碳和水交换中起着重要作用,然而很少有研究在林分尺度上估算它们的叶面积。本研究对一组生长在排水良好和排水不良土壤中的不同年龄北方森林林分中的苔藓植物特定叶面积(SLA)和叶面积指数(LAI)进行了量化。通过使用平板扫描仪确定投影面积,并使用解剖显微镜确定横截面几何形状,来评估特定物种的SLA(三种羽藓、四种泥炭藓属植物以及与毛梳藓混生的沼羽藓)。半表面叶面积通过SLA与活生物量的乘积来计算,并根据在所有林分中收集的覆盖数据进行缩放。在排水良好的林分中,尤其是最老的林分中,塔藓在空间覆盖、生物量和叶面积方面占主导地位,而暗绿泥炭藓和沼羽藓在排水不良的林分中很重要。在以羽藓为主的排水良好的林分中,活苔藓生物量范围为47至230 g m⁻²,在排水不良的林分中为102至228 g m⁻²。苔藓植物的SLA分别在沼羽藓和细叶泥炭藓中为135至473 cm² g⁻¹。SLA受到苔藓植物物种强烈且显著的影响,但在不同林分之间没有差异;一般来说,非泥炭藓类苔藓的SLA之间没有显著差异。苔藓植物的LAI随着林分年龄的增加而增加,在排水良好和排水不良的林分中分别在3.1和3.7时达到峰值;这分别约占排水良好林分中上层林分LAI的40%和排水不良林分中100 - 1000%,突出了苔藓植物在这些北方森林水分和碳收支中所起的重要作用。