J Plant Ecol ›› 2020, Vol. 13 ›› Issue (2): 150-156.DOI: 10.1093/jpe/rtz056

• Research Articles • Previous Articles     Next Articles

Aboveground biomass and seasonal patterns of aboveground net primary productivity in five bamboo species in northern Laos

Singkone Xayalath1, Isao Hirota2, Shinsuke Tomita3 and Michiko Nakagawa1, *   

  1. 1 Department of Forest and Environmental Resource Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan, 2 Department of Agricultural and Environmental Science, Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan, 3 Asian Satellite Campuses Institute, Nagoya University, Nagoya 464-8601, Japan

    *Corresponding author. E-mail: miko@agr.nagoya-u.ac.jp
  • Received:2019-02-05 Revised:2019-12-12 Accepted:2019-12-17 Online:2019-12-23 Published:2020-04-01

Abstract:

Aims

Accurate estimates of bamboo biomass and net primary productivity (NPP) are required to evaluate the carbon sequestration potential of bamboo forests. However, relevant data that are important for climate change mitigation, have rarely been collected in regions outside of East Asia and India. Information on seasonal patterns of NPP and its components will enable the quantification of factors that influence the carbon balance in bamboo forests. In this study, we quantified the aboveground biomass (AGB) and aboveground NPP of five major bamboo species in northern Laos using monthly data collected over a 12-month period.

Methods

All live culms in 10, 2 m × 2 m plots (for one monopodial bamboo species: Indosasa sinica) and 30 clumps per species (for four sympodial bamboo species: Bambusa tuldaCephalostachyum virgatumDendrocalamus membranaceus and Gigantochloa sp.) were numbered and measured at breast height. We set 10 or 20 litter traps per species to collect litterfall. Censuses of dead and recruited culms and litterfall collection were performed once per month for 12 months.

Important Findings

The AGB was highest in I. sinica (59.87 Mg ha−1) and lowest in Cvirgatum (11.54 Mg ha−1), and was mostly below the plausible global range for bamboos (32–256 Mg ha−1). The sympatric distribution of multiple bamboo species at the study sites may have suppressed the AGB in four of the five studied species. The aboveground NPP estimates were between 3.43 and 14.25 Mg ha−1 yr−1; those for D. membranaceus (8.20 Mg ha−1 yr−1) and I. sinica(14.25 Mg ha−1 yr−1) were comparable to mean global estimates for temperate evergreen forests (8.78 Mg ha−1 yr−1) and tropical moist forests (10.56 Mg ha−1yr−1). High culm recruitment rates (15.20–23.39% yr−1) were major contributors to aboveground NPP estimates. Seasonal patterns of aboveground NPP were largely influenced by the phenology of the new culms. In the four sympodial bamboo species, new culms began to emerge following the onset of persistent rainfall, mainly in July and August. However, the sprouting of new culms in the monopodial species I. sinica followed a trend of increasing temperatures, mainly in March and April. Thus, our results indicate that bamboos have considerable potential for sequestering carbon in northern Laos, but that this potential may be affected by climate change.

Key words: bamboo forest, carbon sequestration, culm dynamics, litterfall, northern Laos, seasonality

摘要:
评价竹林的固碳潜力,需要对竹林生物量和净初级生产力(NPP)进行准确的估算。然而,在东亚和印度以外的地区对减缓气候变化很重要的相关数据收集的很少。关于NPP及其组分季节模式的信息将有助于量化影响竹林碳平衡的因素。在本研究中,我们使用了超过12个月的每月数据,对老挝北部5个主要竹林植物的地上生物量(AGB)和地上NPP进行了量化。对四种合轴分枝的竹品种Bambusa tulda, Cephalostachyum virgatum, Dendrocalamus membranaceusGigantochloa sp.,每个物种随机选取30个群丛;对单轴分枝的Indosasa sinica,我们建立了10个2 m × 2 m的样方,对群丛和样方内的所有植株进行编号并测量胸径。我们为每个物种设置了10或20个凋落物收集器来收集凋落物。在12个月的时间里,每月对死亡和新生的群丛进行一次调查。I. sinica的地上生物量(AGB)最大(59.87 Mg ha-1),而C. virgatum的AGB最小(11.54 Mg ha-1),并且大多都低于全球竹子AGB的范围(32-256 Mg ha-1)。研究区多个竹种的同域分布可能抑制了本文所研究的五种竹种中的四种的AGB。地上的NPP估计值在3.43到14.25 Mg ha-1 yr-1之间;这个值在D. membranaceus (8.20 Mg ha-1 yr-1)和I. sinica (14.25 Mg ha-1 yr-1)中,分别与温带常绿森林(8.78 Mg ha-1 yr-1)和热带湿润森林(10.56 Mg ha-1 yr-1)的全球平均估计值相当。较高的群丛新生率(15.20-23.39% yr-1)是地上NPP估计值的主要贡献因素。新竹丛的物候特征对地上NPP的季节模式影响很大。在四种合轴分枝的竹子中,随着持续降雨的开始,新的竹丛开始出现,主要在7月和8月。然而,在单轴分枝的I. sinica中,新竹丛随着温度的上升开始萌芽,主要在3月和4月。因此,我们的结果表明,竹子在老挝北部具有相当大的固碳潜力,但这种潜力可能受到气候变化的影响。

关键词: 竹林, 固碳, 茎动态, 凋落物, 老挝北部, 季节性