Sawgrass above ground biomass from the Taylor Slough, Everglades National Park (FCE LTER), Florida, USA, August 1999 - ongoing

Sawgrass biomass is measured for TS/Ph-1, 2, 3, & 6 since 1999; TS/Ph-4 & 5 since 1997 to 2006; SRS-1b, 2, & 3 since 2000; SRS1c for 2005 to 2006, and SRS1d since 2006. Three 1 m2 plots are placed on each site. The sites are measured every two months. The number of sawgrass plants is counted for each 1 m2 plot and one third or a minimum of fifteen plants is measured. For each measured plant, measurements of the total number of live leaves, length of the live leaves, and culm diameter at the base are taken. From these measurements we calculate the average leaf length, and the sum of the length of the leaves. We created a model for biomass using a stepwise regression to see which of the variables measured and calculated are more correlated to explain plant biomass. Obtaining the mean biomass for the plants within the plot and multiplying it by the number of plants counted in the plot calculates biomass for each plot. The total biomass for each plot is summed with the other two plots in the same site, and they are averaged to obtain one biomass number per site. To validate our model, plant clippings are obtained in which four plants are clipped (small, medium, large, inflorescence) from each site. The same measurements are applied to the clipped plants as those applied to the measured plants in the plots. The plant clippings are oven dried at 70 degrees C and weighed.

自1999年起，针对TS/Ph-1、2、3及6号样地开展锯草（Sawgrass）生物量测定；TS/Ph-4、5号样地的测定时段为1997年至2006年；SRS-1b、2、3号样地的测定始于2000年；SRS1c号样地的测定时段为2005年至2006年，SRS1d号样地的测定则自2006年起。每个样地（site）设置3块1平方米的样方（plot），且每两个月对该样地开展一次测定。对每块样方内的锯草植株总数进行计数，并从中选取三分之一且至少15株植株开展详细测定。针对每株被测植株，记录其存活叶片总数、存活叶片长度以及基部茎秆直径。基于上述实测数据，我们计算得到单株植株的平均叶长与总叶长之和。我们采用逐步回归法构建生物量预测模型，以筛选出与植株生物量相关性最强的实测与衍生变量，实现对植株生物量的精准解释。先计算单块样方内所有被测植株的平均生物量，再乘以该样方内统计得到的植株总数，即可得到该样方的总生物量。将同一样地内3块样方的总生物量求和后取平均值，最终得到该样地的生物量数值。为验证所构建模型的有效性，我们在每个样地采集4株锯草植株（分别为小型、中型、大型植株以及花序）。对采集的剪取植株采用与样地内被测植株完全一致的测量流程。将采集的植株剪样置于70℃烘箱中烘干后称重。