DOI: 10.5061/dryad.36kj534
title: Data from: Immediate and carry-over effects of insect outbreaks on vegetation growth in West Greenland assessed from cells to satellite

description: Aim: Tundra ecosystems are highly vulnerable to climate change and
 climate-growth responses of Arctic shrubs are variable and altered by
 microsite environmental conditions and biotic factors. With warming and
 drought during the growing season, insect-driven defoliation is expected
 to increase in frequency and severity with potential broad-scale impacts
 on tundra ecosystem functioning. Here we provide the first broad-scale
 reconstruction of spatiotemporal dynamics of past insect outbreaks by
 assessing their effects on shrub growth along a typical Greenlandic fjord
 climate gradient from the inland ice to the sea. Location: Nuuk Fjord
 (64°30′N/51°23′W) and adjacent areas, West Greenland. Taxa: Great brocade
 (Eurois occulta L.) and grey willow (Salix glauca L.). Methods: We
 combined dendro-anatomical and remote sensing analyses. Time series of
 ring width and wood-anatomical traits were obtained from chronologies of
 &gt; 40 years established from 153 individuals of S. glauca collected
 at nine sites. We detected anomalies in satellite-based Normalized
 Difference Vegetation Index (NDVI) related to defoliation and
 reconstructed past changes in photosynthetic activity across the region.
 Results: We identified outbreaks as distinctive years with reduced ring
 width, cell-wall thickness and vessel size, without being directly related
 to climate but matching with years of parallel reduction in NDVI. The two
 subsequent years after the defoliation showed a significant increase in
 ring width. The reconstructed spatiotemporal dynamics of these events
 indicate substantial regional variation in outbreak intensity linked to
 the climate variability across the fjord system. Main conclusions: Our
 results highlight the ability of S. glauca to cope with severe insect
 defoliation by changing carbon investment and xylem conductivity leading
 to high resilience and rapid recovery after the disturbance. Our
 multi-proxy approach allows us to pin-point biotic drivers of narrow ring
 formation and to provide new broad-scale insight on the C-budget and
 vegetation productivity of shrub communities in a widespread arctic
 ecosystem
description: Dataset_JBI-19-0066This file includes the data used to analyze: i) time series of wood anatomical features of Salix glauca L., climate and NDVI data from the nine sites in Nuuk Fjord (West Greenland); ii) climate-growth relationship and the effect of the outbreak events; iii) current and potential carry-over effects on growth, anatomical traits and carbon investment; iv) spatial and temporal distribution of the outbreaks. In particular, time series of ring width (RW), growing season Normalized Difference Vegetation Index (NDVI), mean temperature and cumulative precipitation of June-August (T JJA and P JJA respectively) for all the sites and hydraulic diameter (Dh), cell wall thickness of the fibres (CWTf), fibre density (Df) for Iffiartarfik site are considered al local level. Variables are organized in columns and named with the acronyms described in Table 1, Table 2 and Figure 2.Final_Dataset_JBI-19-0066.xlsx