Groundwater and remotely sensed phenology reveal vulnerability of riparian trees to drought

The increasing frequency and magnitude of climatic extremes are altering water availability in dryland ecosystems globally. However, riparian vulnerability to hydroclimate whiplash remains poorly understood. Here, we examined how riparian willow, cottonwood, and valley oak trees respond to groundwater fluctuations and drought through their water use patterns and phenology. To this end, we combined time-series analysis of in situ, high-frequency groundwater monitoring with high-resolution PlanetScope satellite imagery of a drought-prone and relatively pristine watershed in California (Chalone Creek, Pinnacles National Park). We found that flow regime dictates the potential for trees to access groundwater, while the identity of tree species determines the timing and magnitude of their use. Machine-learning models revealed that at intermittent sites, groundwater depth predominantly controlled vegetation greenness, represented by Normalized Difference Vegetation Index (NDVI). In contrast, v..., , # Data from: Groundwater and remotely sensed phenology reveal vulnerability of riparian trees to drought

## Description

This repository contains the data and R code necessary to reproduce the analyses and figures presented in the manuscript, \"Groundwater and remotely sensed phenology reveal vulnerability of riparian trees to drought.\" The analysis investigates the relationship between groundwater availability, drought, and the phenological shifts in riparian tree species.

### Code: Mohammadi_et_al_2025.Rmd

Code description: R Markdown script to reproduce all analyses and figures

#### Dataset: SC-5_all.csv

Dataset description: This dataset contains groundwater elevation data for well SC-5 (perennial) used in the wavelet analysis

date: date

elevation_ft: elevation (ft) of water table

elevation_m: elevation (m) of water table

#### Dataset: CHA-4_all.csv

Dataset description: This dataset contains groundwater elevation data for well CHA-4 (intermittent) used in the wavelet analysi...,