WAT01 Konza Prairie Long-Term Irrigation Transect Study

In 1991, an irrigation transect experiment was established near the Konza Prairie HQ to assess the effects of supplemental water on ecological processes in tallgrass prairie. The site is burned annually in the spring. The transect spans upland, hillside and lowland topographic positions with irrigation and sampling points (12) located at 10 m intervals. Adjacent control transects are marked on both sides of the irrigation transect. Irrigation is scheduled according to estimates of actual evapotranspiration and measures of plant water status. In 1992, an additional 4 irrigation sprinklers were added to the transect (2 at each end). In 1993, a second line of sprinklers and control plots was added (#16-31). At the time of peak aboveground biomass (late August to October), six 0.1 m2 quadrats are harvested at each of the 30 sites (no #9 due to rock outcrop) for the irrigated and control/non-irrigated lines. Biomass is separated into live grass, forb and woody. As of 2006, c.dead is no longer separated from live grass. Vegetative species composition was initially measured in 1991 at each site, and continues to be measured at midseason by using a modified Daubenmire canopy coverage technique in a 10 m2 circular plot. At approximately 10 day intervals, predawn and midday plant water potentials are measured in Andropogon gerardii at each site in both irrigated and control transects. Since 1992, reproductive effort of the dominant grasses Andropogon gerardii (ANGE), Sorghastrum nutans (SONU), Schizachyrium scoparius (ANSC) has been assessed in irrigated and control transects by measuring heights (n=9) and densities (n=4) of flowering stalks. In 1993, soil moisture measurements at 15 and 30 cm depths were begun with a Time Domain Reflectometry system. Data set also includes measured natural precipitation and supplemental water added to the site.

1991年，研究人员在康扎草原总部（Konza Prairie HQ）附近建立灌溉样带实验，以评估补水对高草草原生态过程的影响。该样地每年春季进行火烧。样带涵盖高地、坡地与低地三种地形位置，灌溉与采样点以10米为间隔布设，共设12个点位。灌溉样带两侧均设置了相邻的对照样带。灌溉方案根据实际蒸散量估算值与植物水分状态测定结果制定。1992年，该样带新增4台灌溉喷头（两端各设2台）。1993年，新增第二条喷头管线与对照样区（编号16至31）。在地上生物量峰值期（8月末至10月），灌溉组与对照/非灌溉组的30个采样点位（因岩石露头，无#9点位）各布设6个0.1平方米的样方进行收割取样。收割的生物量被分为活草本、杂类草与木本植物三类。2006年起，不再将枯死生物量组分与活草本分开统计。植物物种组成初始测定于1991年在各点位开展，后续每年在生长季中期，采用改良的道本迈尔（Daubenmire）冠层盖度法，在10平方米的圆形样地中进行测定。每约10天，研究人员会在灌溉与对照样带的各点位，对大须芒草（Andropogon gerardii）测定其黎明前与正午的植物水势。自1992年起，研究人员通过测定开花茎秆的高度（n=9）与密度（n=4），评估灌溉与对照样带中优势草本植物大须芒草（Andropogon gerardii，缩写ANGE）、垂穗草（Sorghastrum nutans，缩写SONU）以及小须芒草（Schizachyrium scoparius，缩写ANSC）的繁殖投入。1993年，研究人员采用时域反射仪（Time Domain Reflectometry）系统对15厘米与30厘米深度的土壤水分进行测定。本数据集还包含样地实测的自然降水量与补水总量。