Data from: APARTS: A cloud-computing tool to reconstruct four decades of ecosystem functioning in arid and semi-arid grasslands

Ecosystem functioning and aboveground net primary productivity (ANPP) are key indicators of land resilience. This dataset supports the validation and ecological application of APARTS (Absorbed Photosynthetically Active Radiation Time Series), a Google Earth Engine (GEE) application that generates monthly APAR estimates (1984–present) by harmonizing Landsat 5, 7, and 8 sensors with ERA5-Land PAR data. This repository is structured into two core modules: Module 1 (Calibration & Validation): Ground-reference seasonal harvest ANPP data from long-term studies in Patagonia wet meadows (Irisarri et al., 2012) and the US Sandhills (Stephenson et al., 2019), paired with matchup satellite-derived indices (NDVI, EVI) and fAPAR formulations. Results show strong empirical relationships, validating APARTS as a robust proxy for biophysical productivity. Module 2 (Ecological Applications): - Case Study 1 (Pilcaniyeu, Argentina): Evaluates the impact of the 2011 Puyehue volcanic eruption. BFAST01 analysis reveals a significant "interruption with a negative break" (Type 5 classification): stable pre-eruption baseline, a sharp drop from ash deposition, and a highly significant (p < 0.001) post-eruption recovery trend (4.45% rate of change), showcasing high resilience. - Case Study 2 (CPER, USA):Analyzes the 2002 and 2012 droughts across three pastures with contrasting grazing legacies (Light, Moderate, High grazing). The data demonstrates how grazing-driven shifts in plant functional types influence resistance and recovery trajectories. How the Data Was Gathered Field Data: Compiled from published historical studies (Irisarri et al., 2012; Stephenson et al., 2019) using standardized biomass clipping and exclusion cages. Satellite Data: Extracted via the APARTS GEE platform. Landsat images were surface-reflectance corrected, harmonized, cloud-masked, and aggregated monthly. PAR (48% of solar radiation) was sourced from ERA5-Land. How to Interpret and Use the Data To ensure reproducibility, we include three documented R scripts: 1. Data_analysis.R: Runs regression models to evaluate APAR/fAPAR against field ANPP. 2. aparts_pilcaniyeu_analysis.R: Performs temporal interpolation and BFAST01 breakpoint detection for the volcanic eruption study. 3. aparts_cper_analysis.R: Automates temporal alignment and runs BFAST01 for CPER grazing pastures. Run these sequentially in R (version >= 4.2.0) to replicate all statistical results and figures.生态系统功能与地上净初级生产力（aboveground net primary productivity, ANPP）是陆地生态系统韧性的核心指标。本数据集用于支撑APARTS（Absorbed Photosynthetically Active Radiation Time Series，吸收光合有效辐射时间序列）的验证与生态应用——该谷歌地球引擎（Google Earth Engine, GEE）应用通过协调Landsat 5、7、8传感器数据与ERA5-Land光合有效辐射（PAR）数据，生成1984年至今的月度光合有效辐射吸收量（APAR）估算结果。 本存储库包含两个核心模块： 模块1（校准与验证）： 收录巴塔哥尼亚湿地草甸（Irisarri等，2012）与美国沙丘地区（Stephenson等，2019）长期定位研究的地面实测季节收获法ANPP数据，配套匹配卫星衍生植被指数（归一化差分植被指数NDVI、增强型植被指数EVI）与光合有效辐射吸收比例（fAPAR）计算方案。实证分析结果显示二者存在强相关关系，验证了APARTS可作为生物物理生产力的可靠替代指标。 模块2（生态应用）： - 案例研究1（阿根廷皮尔卡尼约（Pilcaniyeu））：评估2011年普耶韦火山喷发的生态影响。通过BFAST01分析发现显著的“负中断型断点”（类型5分类）：喷发前处于稳定基线状态，火山灰沉降导致植被生产力骤降，后续恢复趋势极显著（p < 0.001），变化速率达4.45%，体现了生态系统的高韧性。 - 案例研究2（美国CPER地区）：分析2002年与2012年干旱对三类具有不同放牧历史（轻牧、中牧、重牧）牧场的影响。数据揭示了放牧驱动的植物功能型转变如何影响生态系统的抗性与恢复轨迹。 数据采集方式 实地数据：整合自已发表的历史研究（Irisarri等，2012；Stephenson等，2019），采用标准化生物量刈割与排除笼实验方法获取。 卫星数据：通过APARTS的GEE平台提取。Landsat影像经过地表反射率校正、传感器协调、云掩膜处理后按月度聚合。光合有效辐射（PAR，占太阳辐射的48%）数据来源于ERA5-Land数据集。 数据解读与使用说明 为确保研究可重复性，本数据集附带三份经过文档化的R脚本： 1. Data_analysis.R：运行回归模型，对比验证APAR/fAPAR与实地实测ANPP的相关性。 2. aparts_pilcaniyeu_analysis.R：针对火山喷发案例研究，执行时间插值与BFAST01断点检测分析。 3. aparts_cper_analysis.R：自动完成时间对齐，并针对CPER牧场开展BFAST01断点分析。 需在R语言（版本≥4.2.0）中按顺序运行上述脚本，即可复现所有统计结果与可视化图表。