Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） ...Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） subalpine forests in western China were measured to understand the monthly variations in litter nutrient concentrations and annual and monthly nutrient returns via litteffall. Nutrient concentration in litter showed the rank order of Ca 〉 N 〉 Mg 〉 K 〉 S 〉 P. Monthly variations in nutrient concentrations were greater in leaf litter （LL） than other litter components. The highest and lowest concentrations of N, P, K, and S in LL were found in the growing season and the nongrowing season, respectively, but Ca and Mg were the opposite. Nutrient returns via litterfall showed a marked monthly pattern with a major peak in October and one or two small peaks in February and/or May, varying with the element and stand type, but no marked monthly variations in nutrient returns via woody litter, reproductive litter, except in May for the BF, and moss litter. Not only litter production but also nutrient concentration controlled the annual nutrient return and the monthly nutrient return pattern. The monthly patterns of the nutrient concentration and return were of ecological importance for nutrient cycling and plant growth in the subalpine forest ecosystems.展开更多
目的:分析母乳中蛋白质、脂肪、碳水化合物这三类宏量营养素水平与婴儿生长发育的关系。方法:本研究来源中国母乳成分数据库,采用横断面调查设计。在华北、东北、华东、华南、西南、西北招募6481名健康乳母,采用随机抽样抽取858份母乳,...目的:分析母乳中蛋白质、脂肪、碳水化合物这三类宏量营养素水平与婴儿生长发育的关系。方法:本研究来源中国母乳成分数据库,采用横断面调查设计。在华北、东北、华东、华南、西南、西北招募6481名健康乳母,采用随机抽样抽取858份母乳,利用Miris人乳成分分析仪测定母乳中蛋白质、脂肪、碳水化合物水平,并测量婴儿体重、身长、头围等生长指标。采用GLM模型(Generalized Linear Model)分析母乳宏量营养素水平与婴儿体格发育指标之间的关联。结果:母乳蛋白质水平与WAZ(年龄别体重z评分)显著正关联(β=0.17,P<0.05);母乳脂肪水平与婴儿生长发育没有显著关联(BAZ中,β=0.036,P>0.05;LAZ中,β=-0.008,P>0.05;HCZ中,β=0.033,P>0.05;WAZ中,β=0.043,P>0.05;WLZ中,β=0.054,P>0.05)。母乳碳水化合物水平与LAZ(年龄别身长z评分)显著正关联(β=0.19,P<0.01)。结论:母乳蛋白质水平与婴儿体重、母乳碳水化合物水平与婴儿身长可能存在正关联。展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 30471378, 90202010 and 30211130504)the Applied and Basic Research Program of Sichuan Province, and the Talent-Recruiting Program of Sichuan Agricultural University
文摘Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） subalpine forests in western China were measured to understand the monthly variations in litter nutrient concentrations and annual and monthly nutrient returns via litteffall. Nutrient concentration in litter showed the rank order of Ca 〉 N 〉 Mg 〉 K 〉 S 〉 P. Monthly variations in nutrient concentrations were greater in leaf litter （LL） than other litter components. The highest and lowest concentrations of N, P, K, and S in LL were found in the growing season and the nongrowing season, respectively, but Ca and Mg were the opposite. Nutrient returns via litterfall showed a marked monthly pattern with a major peak in October and one or two small peaks in February and/or May, varying with the element and stand type, but no marked monthly variations in nutrient returns via woody litter, reproductive litter, except in May for the BF, and moss litter. Not only litter production but also nutrient concentration controlled the annual nutrient return and the monthly nutrient return pattern. The monthly patterns of the nutrient concentration and return were of ecological importance for nutrient cycling and plant growth in the subalpine forest ecosystems.
文摘目的:分析母乳中蛋白质、脂肪、碳水化合物这三类宏量营养素水平与婴儿生长发育的关系。方法:本研究来源中国母乳成分数据库,采用横断面调查设计。在华北、东北、华东、华南、西南、西北招募6481名健康乳母,采用随机抽样抽取858份母乳,利用Miris人乳成分分析仪测定母乳中蛋白质、脂肪、碳水化合物水平,并测量婴儿体重、身长、头围等生长指标。采用GLM模型(Generalized Linear Model)分析母乳宏量营养素水平与婴儿体格发育指标之间的关联。结果:母乳蛋白质水平与WAZ(年龄别体重z评分)显著正关联(β=0.17,P<0.05);母乳脂肪水平与婴儿生长发育没有显著关联(BAZ中,β=0.036,P>0.05;LAZ中,β=-0.008,P>0.05;HCZ中,β=0.033,P>0.05;WAZ中,β=0.043,P>0.05;WLZ中,β=0.054,P>0.05)。母乳碳水化合物水平与LAZ(年龄别身长z评分)显著正关联(β=0.19,P<0.01)。结论:母乳蛋白质水平与婴儿体重、母乳碳水化合物水平与婴儿身长可能存在正关联。
