Effects of Disturbance and Climate Change on Ecosystem Performance in the Yukon River Basin Boreal Forest

Brian Brisco,Bruce Wylie,Jordan Long,Kevin Murnaghan,Jennifer Rover,Matthew Rigge

doi:10.3390/rs6109145

Abstract

A warming climate influences boreal forest productivity, dynamics, and disturbance regimes. We used ecosystem models and 250 m satellite Normalized Difference Vegetation Index (NDVI) data averaged over the growing season (GSN) to model current, and estimate future, ecosystem performance. We modeled Expected Ecosystem Performance (EEP), or anticipated productivity, in undisturbed stands over the 2000–2008 period from a variety of abiotic data sources, using a rule-based piecewise regression tree. The EEP model was applied to a future climate ensemble A1B projection to quantify expected changes to mature boreal forest performance. Ecosystem Performance Anomalies (EPA), were identified as the residuals of the EEP and GSN relationship and represent performance departures from expected performance conditions. These performance data were used to monitor successional events following fire. Results suggested that maximum EPA occurs 30–40 years following fire, and deciduous stands generally have higher EPA than coniferous stands. Mean undisturbed EEP is projected to increase 5.6% by 2040 and 8.7% by 2070, suggesting an increased deciduous component in boreal forests. Our results contribute to the understanding of boreal forest successional dynamics and its response to climate change. This information enables informed decisions to prepare for, and adapt to, climate change in the Yukon River Basin forest.

Highlights

IntroductionEcosystem productivity in the boreal forest is often constrained by short growing seasons, lack of winter sunlight, temperature, permafrost, low soil nutrient levels [1,2], and disturbance [3,4,5].ecosystem productivity is increasingly limited by mid-summer moisture stress [6,7,8,9].Northwestern North America (and northern latitudes in general) is predicted to continue warming throughout the 21st century, and climatic changes over the last century have already resulted in warmer springs accompanied by an earlier start of growing season [4,10], warmer summers, and much warmer winters [11]
We evaluated the portion of the basin that was either boreal forest
We evaluated the magnitude of disturbance from fire, and the subsequent recovery of Ecosystem Performance Anomalies (EPA), using

Summary

Introduction

Ecosystem productivity in the boreal forest is often constrained by short growing seasons, lack of winter sunlight, temperature, permafrost, low soil nutrient levels [1,2], and disturbance [3,4,5].ecosystem productivity is increasingly limited by mid-summer moisture stress [6,7,8,9].Northwestern North America (and northern latitudes in general) is predicted to continue warming throughout the 21st century, and climatic changes over the last century have already resulted in warmer springs accompanied by an earlier start of growing season [4,10], warmer summers, and much warmer winters [11]. Oscillations (PDO) in the 1970s [12] These changes, combined with ongoing warming, will likely alter the structure [13,14], composition [15,16], distribution [7,17,18], disturbance regimes (increasing severity and frequency of insect outbreaks and fire) [15,19,20], ecosystem services or productivity [2,21,22,23], postfire succession [24], and ecosystem goods and services of the boreal forest. The warming climate may change the limiting factor of tree growth from temperature to moisture [2,7,23], in mid-summer [7,26] These changes will likely result in increased burned area, fire frequency, and fire severity [27]. Boreal deciduous species have been reported to respond more positively to climate change [15,16,25]

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