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首页> 外文期刊>Soil Research >Edaphic and environmental controls of soil respiration and related soil processes under two contrasting manuka and kanuka shrubland stands in North Island, New Zealand.
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Edaphic and environmental controls of soil respiration and related soil processes under two contrasting manuka and kanuka shrubland stands in North Island, New Zealand.

机译：在新西兰北岛的两个麦卢卡和卡努卡灌木林相反的林分之下，对土壤呼吸作用和相关土壤过程的生态和环境控制。

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摘要

The conversion of marginal pastoral land in New Zealand to higher biomass shrubland consisting of manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides var. ericoides) offers opportunity for carbon (C) sequestration, with potential co-benefits of soil erosion control. We therefore selected two areas with different soils in different climatic regions to investigate and compare soil respiration rates, methane and nitrous oxide emission profiles, and key carbon exchange processes controlling carbon sequestration. In addition, two shrubland stands of different ages were selected in each area, providing four sites in total. Regular (almost monthly) soil respiration measurements were made over a 2-year period, with less frequent methane and nitrous oxide flux measurements, and soil sampling once at the end of the study. The cooler, wetter volcanic soils had higher total organic C (6.39+or-0.12% v. 5.51+or-0.17%), soil C:nitrogen (N) ratios (20.55+or-0.20 v. 18.45+or-0.23), and slightly lower mineral N (3.30+or-0.74 v. 4.89+or-0.57 mg/kg) and microbial biomass C (1131+or-108 v. 1502+or-37 mg/kg) than the more drought-prone, stony, sedimentary soils. Mineral-N contents at all sites indicated N-limited ecosystems for allocation of below- and above-ground C. The estimated mean annual cumulative respiration rate recorded in the volcanic soil was 10.26+or-7.45t CO2-C/ha.year compared with 9.85+or-8.63t CO2-C/ha.year in the stony sedimentary soil for the 2 years of our study. Older shrubland stands had higher respiration rates than younger stands in both study areas. Methane oxidation was estimated to be higher in the volcanic soil (4.10+or-2.13 kg CH4-C/ha.year) than the sedimentary soil sites (2.51+or-2.48 kg CH4-C/ha.year). The measured natural background levels of nitrous oxide emissions from these shrubland soils ranged between negligible and 0.30+or-0.20 kg N2O-N/ha.year. A strong climatic control (temperature and moisture) on gas fluxes was observed at all sites. Our sampling strategy at each of the four sites was to estimate the mean soil respiration rates (n=25) from an 8 by 8 m sampling grid positioned into a representative location. Soil respiration rates were also measured (by additional, less frequent sampling) in two adjacent grids (1-m offset and 100-m distant grid) to test the validity of these representative mean values. The 1-m offset grid (n=25) provided a statistically different soil respiration rate from the main grid (n=25) in 25% of the 12 sampling events. The 100-m grid (n=25) provided a statistically different respiration rate to the main grid in 38% of the 26 sampling events. These differences are attributed to the spatially variable and sporadic nature of gaseous emissions from soils. The grid analysis tested the prediction uncertainty and it provides evidence for strong spatial and temporal control by edaphic processes in micro-sites. A partial least-squares regression model was used to relate the 2009 annual cumulative soil respiration to site-specific edaphic characteristics, i.e. biomass, nutrient availability, porosity and bulk density, measured at the end of that year. The model explained >=80% of the variance at three of the four sites.
机译：新西兰边缘的牧区土地向由麦卢卡（Leptospermum scoparium）和卡努卡（Kunzea ericoides var。ericoides）组成的较高生物量灌木丛的转化提供了碳（C）隔离的机会，同时具有土壤侵蚀控制的潜在协同效益。因此，我们选择了两个在不同气候区域具有不同土壤的地区，以调查和比较土壤呼吸速率，甲烷和一氧化二氮排放特征以及控制碳固存的关键碳交换过程。此外，在每个区域选择了两个不同年龄的灌木林林分，总共提供了四个地点。在两年的时间内进行定期（几乎每月一次）的土壤呼吸测量，甲烷和一氧化二氮通量测量的频率降低，并且在研究结束时对土壤进行一次采样。较凉爽，湿润的火山土壤总有机碳含量较高（6.39+或-0.12％v。5.51+或-0.17％），土壤C：氮（N）的比例（20.55+或-0.20 v。18.45 + or-0.23） ，而比干旱多发的地区，矿物质氮（3.30+或-0.74 v。4.89+或-0.57 mg / kg）和微生物生物量C（1131+或-108 v。1502+或-37 mg / kg）略低。 ，石质，沉积性土壤。所有地点的矿物质N含量表明，地下和上层C的氮分配有限。在火山土壤中记录的年平均累积呼吸速率估计为10.26+或-7.45t CO 2 -C / ha.year与9.85+或-8.63t CO 2 -C / ha.year相比。在两个研究区中，较早的灌木林林分的呼吸速率均比较年轻的灌木林高。据估计，火山土壤中甲烷氧化（4.10+或-2.13 kg CH 4 -C / ha.year）高于沉积土壤部位（2.51+或-2.48 kg CH ） 4 -C / ha.year）。从这些灌丛土壤中测得的自然背景中的一氧化二氮排放水平可忽略不计，为0.30+或0.20 kg N 2 O-N / ha.year。在所有地点都观察到强烈的气候控制（温度和湿度）。我们在这四个地点中的每个地点的采样策略是从位于代表性位置的8 x 8 m采样网格估计平均土壤呼吸速率（n = 25）。还测量了两个相邻网格（偏移为1-m的网格和距离为100m的网格）中的土壤呼吸速率（通过额外的，不频繁的采样），以测试这些代表性平均值的有效性。在12个采样事件中有25％的情况下，1-m偏移网格（n = 25）在统计上不同于主网格（n = 25）。在26个采样事件中的38％中，100米网格（n = 25）为主网格提供了统计上不同的呼吸速率。这些差异归因于土壤气体排放的空间可变性和偶发性。网格分析测试了预测的不确定性，并为微观站点中的前缘过程提供了强有力的时空控制证据。使用偏最小二乘回归模型将2009年底的累积土壤呼吸作用与特定地点的土壤养分特征联系起来，即该年末测得的生物量，养分利用率，孔隙度和容重。该模型解释了四个站点中三个站点的> = 80％的方差。

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