TY - JOUR

T1 - Regeneration of Metrosideros polymorpha forests in Hawaii after landscape-level canopy dieback

AU - Mertelmeyer, Linda

AU - Jacobi, James D.

AU - Brinck, Kevin

AU - Mueller-Dombois, Dieter

AU - Boehmer, Hans Juergen

N1 - Funding information: information U.S. Geological Survey, Pacific Island Ecosystems Research Center. This research was supported by funds from the Ecosystems Mission Area of the U.S. Geological Survey, and administrative support provided by the U.S. Geological Survey’s Pacific Island Ecosystems Research Center. We thank Sam Gon III, R. Flint Hughes, Kylle Roy, Gordon Tribble, and two anonymous reviewers for their constructive comments on the manuscript. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. This research was supported by funds from the Ecosystems Mission Area of the U.S. Geological Survey, and administrative support provided by the U.S. Geological Survey’s Pacific Island Ecosystems Research Center. We thank Sam Gon III, R. Flint Hughes, Kylle Roy, Gordon Tribble, and two anonymous reviewers for their constructive comments on the manuscript. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.

PY - 2019

Y1 - 2019

N2 - Questions: (a) Have Metrosideros polymorpha trees become re-established in Hawaiian forests previously impacted by canopy dieback in the 1970s? (b) Has canopy dieback expanded since the 1970s? (c) Can spatial patterns from this dieback be correlated with habitat factors to model future dieback in this area? Study Site: An 83,603 ha study area on the eastern slopes of Mauna Loa and Mauna Kea volcanoes on the island of Hawaii, USA. Methods: We analyzed very-high-resolution imagery to assess status of Metrosideros polymorpha forests across the eastern side of the island of Hawaii. We generated 1,170 virtual vegetation plots with a 100-m radius; 541 plots in areas mapped in 1977 with trees dead or mostly defoliated (dieback), and 629 plots in adjacent wet forest habitat, previously mapped as non-dieback condition. In each plot we estimated the frequency of M. polymorpha trees that were dead or mostly defoliated, and the frequency of trees with healthy crowns. These results were combined with habitat data to produce a spatial model depicting probability of canopy dieback within the study area. Results: Seventy-nine percent of plots mapped in 1977 in dieback condition recovered their canopy and were now considered in non-dieback condition. Ninety-one percent of plots in previous non-dieback areas were found to still have a healthy M. polymorpha canopy in 2015. A spatial model allowed us to identify areas within the study area with high, medium, and low probability of experiencing this same type of canopy dieback in the future. Conclusions: Most former dieback areas mapped within the study area in 1977 now show recovery of the tree canopy through growth of new cohorts of young M. polymorpha trees. This suggests these forest communities are resilient to this type of canopy loss and tree death so long as other factors do not disrupt the natural regeneration process.

AB - Questions: (a) Have Metrosideros polymorpha trees become re-established in Hawaiian forests previously impacted by canopy dieback in the 1970s? (b) Has canopy dieback expanded since the 1970s? (c) Can spatial patterns from this dieback be correlated with habitat factors to model future dieback in this area? Study Site: An 83,603 ha study area on the eastern slopes of Mauna Loa and Mauna Kea volcanoes on the island of Hawaii, USA. Methods: We analyzed very-high-resolution imagery to assess status of Metrosideros polymorpha forests across the eastern side of the island of Hawaii. We generated 1,170 virtual vegetation plots with a 100-m radius; 541 plots in areas mapped in 1977 with trees dead or mostly defoliated (dieback), and 629 plots in adjacent wet forest habitat, previously mapped as non-dieback condition. In each plot we estimated the frequency of M. polymorpha trees that were dead or mostly defoliated, and the frequency of trees with healthy crowns. These results were combined with habitat data to produce a spatial model depicting probability of canopy dieback within the study area. Results: Seventy-nine percent of plots mapped in 1977 in dieback condition recovered their canopy and were now considered in non-dieback condition. Ninety-one percent of plots in previous non-dieback areas were found to still have a healthy M. polymorpha canopy in 2015. A spatial model allowed us to identify areas within the study area with high, medium, and low probability of experiencing this same type of canopy dieback in the future. Conclusions: Most former dieback areas mapped within the study area in 1977 now show recovery of the tree canopy through growth of new cohorts of young M. polymorpha trees. This suggests these forest communities are resilient to this type of canopy loss and tree death so long as other factors do not disrupt the natural regeneration process.

KW - Canopy dieback

KW - Cohort senescence

KW - Forest decline

KW - Forest health

KW - Hawaii

KW - Landscape-level analysis

KW - Metrosideros polymorpha

KW - Ohia

KW - Recovery

KW - Regeneration

KW - Tree mortality

KW - Vegetation dynamics

UR - http://www.scopus.com/inward/record.url?scp=85067692067&partnerID=8YFLogxK

U2 - 10.1111/jvs.12704

DO - 10.1111/jvs.12704

M3 - Article

AN - SCOPUS:85067692067

VL - 30

SP - 146

EP - 155

JO - Journal of vegetation science

JF - Journal of vegetation science

SN - 1100-9233

IS - 1

ER -