Plant phenology and performance in the International Tundra Experiment (ITEX) plots at Utqiaġvik and Atqasuk, Alaska

Arctic ecosystems are changing in response to arctic warming, which is proceeding more than twice as fast as the global average. The International Tundra Experiment (ITEX) was established in the early 1990s to understand the effects of warming and environmental variability on tundra vegetation properties and ecosystem function. The ITEX program has been extremely valuable for detection of changes in tundra plant and ecosystem responses to experimental warming and to background climate change across sites that span the major ecosystems of the Arctic. These files contain data representing the periodic plant measures of all species within each plot in a text comma delimited format. The data presented are phenological development (date of leaf bud burst, inflorescence emergence, flower bud, flower opening, flower withering, seed development, seed dispersal, and senescence), seasonal growth (length of leaf, and length of inflorescence), seasonal flowering (number of inflorescences in flower within a plot), occurrence of events (yes or no for leaf, inflorescence, bud, flower, and seed), and annual growth and reproductive effort (number of leaves, diameter of rosette, number of branches, maximum leaf length, number of inflorescences, maximum inflorescence length, number of buds, number of flowers, and number of seeds) collected weekly or yearly for all plant species during the summers of 1994-2019 for 48 plots (24 experiment open-top chamber plots and 24 control plots) at four sites (Atqasuk Wet Meadow, Atqasuk Dry Heath, Utqiaġvik Wet Meadow, and Utqiaġvik Dry Heath) and during the summer of 2021 at two sites (Utqiaġvik Wet Meadow and Utqiaġvik Dry Heath).

北极生态系统正随北极变暖发生演变，而北极变暖速率是全球平均水平的两倍有余。国际苔原实验计划（International Tundra Experiment, ITEX）于20世纪90年代初启动，旨在探究增温与环境变异对苔原植被特征及生态系统功能的影响。该项目覆盖北极各大主要生态系统的多个样点，为检测苔原植物及生态系统对实验增温与背景气候变化的响应变化提供了极为宝贵的研究支撑。本批文件以逗号分隔的文本格式，存储了各监测样地内所有植物物种的周期性监测数据。所呈现的数据涵盖：物候发育（叶芽萌发期、花序伸出期、花蕾期、花朵开放期、花朵枯萎期、种子发育期、种子扩散期及衰老期）、季节生长指标（叶片长度与花序长度）、季节开花指标（样地内开花花序总数）、事件发生情况（叶片、花序、芽、花及种子相关事件的有无），以及年度生长与繁殖投入指标（叶片数量、莲座直径、分枝数、最大叶长、花序数量、最大花序长度、花蕾数量、花朵数量及种子数量）。上述数据于1994-2019年夏季，在48个样地（24个开顶式气室（open-top chamber）增温实验样地与24个对照样地）的4个站点（阿塔苏克湿草甸、阿塔苏克干石楠灌丛、乌特恰维克湿草甸及乌特恰维克干石楠灌丛）按周或年度采集；并于2021年夏季在乌特恰维克湿草甸、乌特恰维克干石楠灌丛2个站点补充采集。