Below-Ground Net Primary Production (BNPP): Root Ingrowth Donuts in Chihuahuan Desert Grassland and Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico

In 2005, annually harvested root ingrowth donut structures were co-located with previously established mini-rhizotron tubes established at four sites on McKenzie Flats located on the east side of Sevilleta NWR: 10 replicate structures in both burned and unburned blue and black grama dominated grassland plots at Deep Well, 10 replicates each on nitrogen fertilization plots and respective control plots on McKenzie Flats(20 total), 10 replicates in creosote dominated shrubland at the Five Points Creosote Core site and in 2011, 13 structures were put in the Monsoon site. Roots and soil are harvested annually in late fall after the growing season, and structures are reestablished in situ for consecutive harvests each year. Each structure allows roots to be harvested at two depths (0-15 and 15-30 cm) to estimate root production, or below ground net primary productivity. In order to compare estimates of root production from two methods, root ingrowth donuts were collocated with mini-rhizotron tubes at all localities except for the burned grassland plot at Deep Well.

2005年，研究人员在塞维利塔国家野生动物保护区（Sevilleta NWR）东侧的麦肯齐平原（McKenzie Flats）的4个样地中，将年度收获型根生长环结构（root ingrowth donut structures）与预先布设的微根窗管（mini-rhizotron tubes）进行协同定位：在深井样地的火烧与未火烧的蓝茎格兰马草（blue grama）、黑格兰马草（black grama）占优势的草地样地中各设置10个重复根生长环结构；在麦肯齐平原的氮肥添加样地及对应的对照样地中各设置10个重复结构（共计20个）；在五点杂酚油灌丛核心样地（Five Points Creosote Core site）的杂酚油（creosote）占优势的灌丛群落中设置10个重复结构；2011年，在季风样地（Monsoon site）布设了13个该结构。每年于生长季结束后的晚秋开展根系与土壤收获工作，并于原位重新布设根生长环结构，以实现年度连续采样。每个根生长环结构可在两个土层深度（0~15 cm与15~30 cm）处采集根系，用于估算根系生产量或地下净初级生产力。为对比两种方法的根系生产量估算结果，除深井样地的火烧草地样地外，所有样地均将根生长环结构与微根窗管进行协同定位。