Stand dynamics of old-growth hemlock forests in central Bhutan are shaped by natural disturbances  

作　　者：Karma Tenzin Craig R.Nitschke Kathryn J.Allen Raphael Trouve Thiet V.Nguyen Patrick J.Baker 

机构地区：[1]School of Agriculture,Food,and Ecosystem Sciences,University of Melbourne,500 Yarra Blvd,Richmond,Victoria,Australia [2]School of Geography,Planning,and Spatial Sciences,University of Tasmania,Sandy Bay,Tasmania,Australia [3]Forest Science Institute of South Vietnam,1 Pham Van Hai Street,Tan Binh District,Ho Chi Minh City,Viet Nam

出　　处：《Forest Ecosystems》2024年第4期434-447,共14页森林生态系统（英文版）

基　　金：support by Melbourne International Research Scholarship (MIRS)。

摘　　要：Understanding how past disturbances have influenced the development of forests is critical for deciphering their current structure and composition and forecasting future changes.In this study,dendrochronological methods were applied to uncover the disturbance history of old-growth hemlock-dominated forests in central Bhutan.Analysis of tree-ring samples from two old-growth hemlock stands,located in two different topographic settings,identified the importance of gap-phase dynamics in facilitating recruitment and growth releases and producing complex,multi-aged structure s over time.One site showed evidence of a near stand-replacing disturbance in the late 1700s,while the other showed no evide nce of high-severity disturbance at any time over the last 400 years.At both sites low-to medium-severity disturbances,some of which appear to be associated with cyclones originating in the Bay of Bengal,dominated the disturbance regime.The hemlock stands exhibited a significant positive association between cyclone occurrence and growth release events and between recruitment pulses and growth release events.From 1800 to 1970 there was an increase in recruitment of angiosperm tree species at most sites and a corresponding decline in conifer recruitment.Over the past 50 years there has been little new recruitment;this may be due to light limitation in the understory from shade-tolerant angiosperms and bamboo in the lower strata of these stands.Significant variations in disturbance dynamics and recruitment were observed across the study sites,suggesting that other factors,such as topography and climate,may be influencing long-term stand development patterns.This study highlights the complex interplay between historical disturbance regimes and tree recruitment in shaping the age and size structures of old-growth hemlock forests in central Bhutan.It also provides new insights into the dynamics of these forests that can be used to support effective forest conservation and management in the future.

关 键 词：Forest structure Hemlock forest HIMALAYA Natural disturbance 

分 类 号：S718.5[农业科学—林学]