Spatiotemporal variations of albedo in managed agricultural landscapes: inferences to global warming impacts (GWI)

Abstract

Albedo can be used to quantify ecosystem and landscape contributions to local and global climate. Such contributions are conventionally expressed as radiative forcing (RF) and global warming impact (GWI). We contextualize our results within landscape carbon production and storage to highlight the importance of changes in albedo for landscape GWI from multiple causes, including net ecosystem production (NEP) and greenhouse gas (GHG) emissions. To examine the spatiotemporal changes in albedo (Δα) in contrasting managed landscapes through calculations of albedo-induced RF (RFΔα) and GWI (GWIΔα) under different climatic conditions. We selected five contrasting landscapes within the Kalamazoo River watershed in southern Michigan USA as proof of concept. The daily MCD43A3 MODIS (V006) product was used to analyze the inter- and intra-annual variations of growing season albedo. In addition, the variations of RFΔα and GWIΔα were computed based on landscape composition and climate. The RFΔα (− 5.6 W m−2) and GWIΔα (− 1.3 CO2eq ha−1 year−1) were high in forest-dominated landscapes, indicating cooling effects and CO2eq mitigation impacts similar to crops. The CO2eq mitigation of cropland-dominated landscapes was on average 52% stronger than forest-dominated landscapes. In the landscape with the highest proportion of forest, under dry and wet conditions CO2eq mitigation was reduced by up to 24% and ~ 30%, respectively; in one cropland-dominated landscape wet conditions reduced CO2eq mitigation by 23%. Findings demonstrate that quantifying spatiotemporal changes in albedo in managed landscapes and under different climatic conditions is essential to understand how landscape modification affects RFΔα and GWIΔα and thereby contributes to ecosystem-level GWI.