AgResearch, Grasslands Research Centre, Private Bag 11008, Palmerston North, New Zealand.
AgResearch, Grasslands Research Centre, Private Bag 11008, Palmerston North, New Zealand.
Sci Total Environ. 2020 May 1;715:136910. doi: 10.1016/j.scitotenv.2020.136910. Epub 2020 Jan 24.
There is increasing interest in the potential of trees to sequester carbon (C) in above- and below-ground stocks to mitigate against increasing concentrations of greenhouse gases (GHG). This study determined whether pasture-tree (PT) systems influence soil C stocks compared with open pasture (OP) by sampling four sites with trees aged 14 to16 years. Poplars (Populus spp.) at Tikokino and Woodville and alders (Alnus spp.) at Poukawa and Ruakura were planted on contrasting soils (Haplustands, Endoaquepts, Durustalfs and Humaquepts, respectively). Trees at all four sites were arranged in partial-Nelder radial planting designs, with five stem densities ranging from 67 to 1276 stems ha. Soils were sampled at five stem density classes, along with adjacent OP areas in the same paddock, to a depth of 1 m (0-75, 75-150, 150-300, 300-600, 600-1000 mm). At three of the four sites, root mass density was greater (P < 0.05) in PT than in OP systems. At Woodville, estimates of total soil C mass to 1 m tended to be greater (P = 0.08) in the OP than in the PT system (200 vs. 163 Mg C ha, respectively), whereas no significant differences in total soil C masses between OP and PT were shown at the remaining sites (P > 0.10). Despite the limited statistical significance, estimates of total soil C mass at Tikokino and Woodville (sites with poplars) were 11 and 18% greater in OP than in PT systems, whereas estimates at Poukawa and Ruakura (sites with alders) were 2 and 6% greater in PT than in OP systems. Under the current conditions, our study suggests that tree species may be an additional factor influencing the C cycle and C accumulation in soils and need to be considered in the building of our soil C inventories.
人们越来越关注树木在固存地上和地下碳储量方面的潜力，以减轻温室气体（GHG）浓度不断增加的影响。本研究通过对四个 14 至 16 岁的树木样地进行采样，确定了牧场-树木（PT）系统与开阔牧场（OP）相比是否会影响土壤碳储量。在 Tikokino 和 Woodville 种植了杨树（Populus spp.），在 Poukawa 和 Ruakura 种植了桤木（Alnus spp.），这些树木分别种植在不同的土壤上（Haplustands、Endoaquepts、Durustalfs 和 Humaquepts）。四个地点的树木都采用部分 Nelder 径向种植设计，树干密度从 67 株/公顷到 1276 株/公顷不等。在五个树干密度范围内（0-75、75-150、150-300、300-600、600-1000mm），对土壤样本进行了采样，同时还对同一围场内的相邻 OP 区域进行了采样，深度达 1m。在四个地点中的三个地点，PT 系统中的根质量密度大于 OP 系统（P<0.05）。在 Woodville，OP 系统中到 1m 的土壤总碳质量估计值（P=0.08）大于 PT 系统（分别为 200 比 163 Mg C ha），而在其余两个地点，OP 和 PT 之间的土壤总碳质量没有显著差异（P>0.10）。尽管统计意义有限，但在 Tikokino 和 Woodville（种植杨树的地点）的估计值中，OP 系统中的总土壤碳质量比 PT 系统高 11%和 18%，而在 Poukawa 和 Ruakura（种植桤木的地点）的估计值中，PT 系统中的总土壤碳质量比 OP 系统高 2%和 6%。在当前条件下，我们的研究表明，树种可能是影响土壤碳循环和碳积累的另一个因素，在建立土壤碳储量时需要考虑这一因素。
