Management intensity controls soil N2O fluxes in an Afromontane ecosystem.
Management intensity controls soil N2O fluxes in an Afromontane ecosystem.
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DOI：
10.1016/j.scitotenv.2017.12.081
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发表时间：
2018-05
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通讯作者：
I. Wanyama;I. Wanyama;D. Pelster;D. Pelster;C. Arias‐Navarro;C. Arias‐Navarro;C. Arias‐Navarro;K. Butterbach‐Bahl;K. Butterbach‐Bahl;Louis V. Verchot;M. Rufino;M. Rufino
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作者：
I. Wanyama;I. Wanyama;D. Pelster;D. Pelster;C. Arias‐Navarro;C. Arias‐Navarro;C. Arias‐Navarro;K. Butterbach‐Bahl;K. Butterbach‐Bahl;Louis V. Verchot;M. Rufino;M. Rufino
量化非洲热带森林和邻近管理土地使用的一氧化二氮（N2 O）通量的研究很少。过去几十年来，小农户农业和商业性农业向肯尼亚最大的山地森林Mau森林扩展，造成了大规模的土地使用变化。我们测量了2015年8月至2016年7月天然林的年度土壤N2 O通量，并将其与小农放牧和茶叶生产或商业茶叶和桉树种植园（n= 18）管理的土地的N2 O通量进行了比较。在上午8：00至11：30之间从5个混合静态室收集空气样品，并在每个图中用于计算气体通量率。小农户的土壤N2 O年通量介于0.2 - 2.9 kg N ha− 1 yr − 1之间，商业农业用地的土壤N2 O年通量介于0.6-1.7 kg N ha− 1 yr − 1之间，土地利用之间没有差异（分别为p= 0.98和p = 0.18）。土地使用之间存在着明显的差异，特别是在小农户管理的土地使用之间，其管理也存在很大差异。施用化肥和牲畜密度高的地块显示出最高的N2 O通量（1.6 ± 0.3 kg N2 O-N ha− 1 yr − 1，n= 7），其次是天然林（1.1 ± 0.1 kg N2 O-N ha− 1 yr − 1，n= 6）;尽管这些没有显著差异（p= 0.19）。在很少或没有输入的地块上发现了显著较低的通量（0.5 ± 0.1 kg N ha− 1 yr − 1，p<0.01，n = 5）。每日土壤N2 O通量与同期测量的水填充孔隙空间（WFPS），土壤温度或无机氮（IN）浓度不相关。然而，IN强度，暴露的土壤微生物（在时间和幅度）IN浓度的措施与年土壤N2 O通量密切相关。
Studies that quantify nitrous oxide (N2O) fluxes from African tropical forests and adjacent managed land uses are scarce. The expansion of smallholder agriculture and commercial agriculture into the Mau forest, the largest montane forest in Kenya, has caused large-scale land use change over the last decades. We measured annual soil N2O fluxes between August 2015 and July 2016 from natural forests and compared them to the N2O fluxes from land either managed by smallholder farmers for grazing and tea production, or commercial tea and eucalyptus plantations (n= 18). Air samples from 5 pooled static chambers were collected between 8:00 am and 11:30 am and used within each plot to calculate the gas flux rates. Annual soil N2O fluxes ranged between 0.2 and 2.9 kg N ha− 1yr− 1at smallholder sites and 0.6–1.7 kg N ha− 1yr− 1at the commercial agriculture sites, with no difference between land uses (p= 0.98 andp= 0.18, respectively). There was marked variation within land uses and, in particular, within those managed by smallholder farmers where management was also highly variable. Plots receiving fertilizer applications and those with high densities of livestock showed the highest N2O fluxes (1.6 ± 0.3 kg N2O-N ha− 1yr− 1,n= 7) followed by natural forests (1.1 ± 0.1 kg N2O-N ha− 1yr− 1,n= 6); although these were not significantly different (p= 0.19). Significantly lower fluxes (0.5 ± 0.1 kg N ha− 1yr− 1,p< 0.01,n= 5) were found on plots that received little or no inputs. Daily soil N2O flux rates were not correlated with concurrent measurements of water filled pore space (WFPS), soil temperature or inorganic nitrogen (IN) concentrations. However, IN intensity, a measure of exposure of soil microbes (in both time and magnitude) to IN concentrations was strongly correlated with annual soil N2O fluxes.