Net Ecosystem Exchange, Ecosystem Respiration and meteoclimatic data of Alpine grasslands at Nivolet Plain, Gran Paradiso National Park, Italy 2017-2023

This dataset presents georeferenced measurements collected at the Nivolet Plain in Gran Paradiso National Park (GPNP), western Italian Alps. The dataset includes the Net Ecosystem Exchange (NEE), Ecosystem Respiration (ER) and meteo-climatic variables, i.e. air and soil temperature, air relative humidity, soil volumetric water content, atmospheric pressure and solar irradiance. The measurements were conducted between 2017 and 2023 at five different sites at an elevation of approximately 2550-2750 meters a.s.l. To estimate NEE and ER, we employed the flux chamber method, measuring the temporal variation of carbon dioxide (CO2) concentration inside the chamber over a period of about 90 seconds. We used a customized portable non-steady-state dynamic flux chamber, paired with an InfraRed Gas Analyzer (IRGA) and a portable weather station. Measurements were taken at around 20 points per site during the snow-free season, spanning from June to October. The dataset is provided in a comma-separated text file (.csv) format. Each record corresponds to a single measurement point, with semicolons used as separators. The "NA" notation indicates values that are not available or have been excluded during quality control processes (e.g., due to battery failure). We use point as decimal separator. The sign convention for the fluxes is: a negative value indicates a CO2 flux from the atmosphere to the ecosystem, while a positive value represents a CO2 flux from the soil/ecosystem to the atmosphere. Consequently, ER values are positive, while NEE values can be positive or negative. The units for NEE and ER fluxes are molCO2 m-2 day-1 and μmolCO2 m-2 second-1. The first values in each record of the dataset indicate the observation details (sampling date, site, etc.), followed by the corresponding measured or calculated variables. NEE and ER values were estimated from the slope of the linear regression of CO2 concentration over time (ppm s-1) using a laboratory calibration curve. The calibration curve was created by relating known and pre-set CO2 fluxes (within the range expected in the field) with the corresponding measured slopes. The flux values were then scaled up based on the area of the chamber base (0.036 m2) and adjusted using the ratio of atmospheric pressure and air temperature during the measurement to those recorded during the calibration in the laboratory.本数据集收录了意大利阿尔卑斯山西侧格兰帕拉迪索国家公园（Gran Paradiso National Park, GPNP）尼沃莱特平原采集的地理参考测量数据。数据集涵盖生态系统净交换量（Net Ecosystem Exchange, NEE）、生态系统呼吸量（Ecosystem Respiration, ER）以及气象气候变量，具体包括空气与土壤温度、空气相对湿度、土壤体积含水量、大气压强与太阳辐照度。本次测量于2017年至2023年间，在海拔约2550至2750米（以海平面为基准）的5个不同点位开展。 为估算NEE与ER，研究采用通量箱法，通过监测通量箱内二氧化碳（CO₂）浓度在约90秒时长内的时间变化量完成测算。研究使用定制化便携式非稳态动态通量箱，搭配红外气体分析仪（InfraRed Gas Analyzer, IRGA）与便携式气象站开展测量。在无雪季（6月至10月）期间，每个点位约采集20个测量点的数据。 本数据集以逗号分隔文本文件（.csv）格式存储，每条记录对应单个测量点，且以分号作为字段分隔符。“NA”标识表示质量控制过程中不可用或已排除的数据（例如因电池故障导致的无效数据）。本数据集采用点号作为十进制分隔符。 通量的符号约定规则为：负值表示二氧化碳从大气流向生态系统，正值则表示二氧化碳从土壤/生态系统流向大气。据此，ER值为正值，而NEE值可正可负。NEE与ER通量的单位分别为molCO₂ m⁻²·day⁻¹与μmolCO₂ m⁻²·s⁻¹。每条数据集记录的首个字段为观测详情（采样日期、点位信息等），其后为对应的实测或计算得到的变量。NEE与ER值通过基于实验室校准曲线，对二氧化碳浓度随时间变化的线性回归斜率（单位为ppm s⁻¹）估算得到。 校准曲线通过将已知预设的二氧化碳通量（处于野外实测预期范围内）与对应测得的斜率相关联构建而成。随后根据通量箱底座面积（0.036 m²）对通量值进行尺度转换，并结合测量时的大气压强与空气温度，与实验室校准阶段记录的对应参数之比进行校正。