Understanding and predicting frost‐induced tropical tree mortality patterns

• Published in: Global change biology Vol. 25; no. 11; pp. 3817 - 3828
• Main Authors: Bojórquez, Adrián, Álvarez‐Yépiz, Juan C., Búrquez, Alberto, Martínez‐Yrízar, Angelina
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.11.2019
• Subjects: Air masses; Air temperature; Climate; Climate models; Cold waves; Dry forests; Ecological succession; Ecosystem; Ecosystem services; Elevation; extreme climatic events; forest dieback; forest die‐off; Forest ecosystems; Forests; Frost; Landscape; Mexico; Mortality; Mortality patterns; Probability theory; Temperature distribution; topography; Topography (geology); tree mortality; Trees; Tropical Climate; tropical dry forest; Tropical forests; Weather; Wood; Woody plants; Mexico; tree mortality; extreme climatic events; forest die-off; frost; forest dieback; topography; tropical dry forest
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.14775

Extreme climatic and weather events are increasing in frequency and intensity across the world causing episodes of widespread tree mortality in many forested ecosystems. However, we have a limited understanding about which local factors influence tree mortality patterns, restricting our ability to predict tree mortality, especially within topographically complex tropical landscapes with a matrix of mature and secondary forests. We investigated the effects of two major local factors, topography and forest successional type, on climate‐induced tropical tree mortality patterns using an observational and modeling approach. The northernmost Neotropical dry forest endured an unprecedented episode of frost‐induced tree mortality after the historic February 2011 cold wave hit northwestern Mexico. In a moderately hilly landscape covering mature and secondary tropical dry forests, we surveyed 454 sites for the presence or absence of frost‐induced tree mortality. In addition, across forty‐eight 1 ha plots equally split into the two forest types, we examined 6,981 woody plants to estimate a frost‐disturbance severity metric using the density of frost‐killed trees. Elevation is the main factor modulating frost effects regardless of forest type. Higher occurrence probabilities of frost‐induced tree mortality at lowland forests can be explained by the strong influence of elevation on temperature distribution since heavier cold air masses move downhill during advective frosts. Holding elevation constant, the probability of frost‐induced tree mortality in mature forests was twice that of secondary forests but severity showed the opposite pattern, suggesting a cautious use of occurrence probabilities of tree mortality to infer severity of climate‐driven disturbances. Extreme frost events, in addition to altering forest successional pathways and ecosystem services, likely maintain and could ultimately shift latitudinal and altitudinal range margins of Neotropical dry forests. Extreme climatic and weather events are increasing in frequency and intensity across the world causing episodes of widespread tree mortality. We investigated the effects of two major local factors, topography and forest successional type, on climate‐induced tropical tree mortality patterns in northwestern Mexico using an observational and modeling approach. Elevation is the main factor modulating frost effects. Holding elevation constant, the probability of frost‐induced tree mortality in mature forests was twice that of secondary forests but severity showed the opposite pattern, suggesting a cautious use of occurrence probabilities of tree mortality to infer climate‐driven disturbance severity.