黑龙江省森林火后冠层垂直结构生态恢复轨迹OA

Forest fires are a major disturbance affecting the structure and functioning of forest ecosystems,and a system-atic assessment of post-fire forest structural recovery is essential for regional ecological security and forest management.Taking fire-affected forests in Heilongjiang Province as the study area,this study used global ecosystem dynamics investi-gation(GEDI)LiDAR data combined with a space-for-time substitution approach to analyze the ecological recovery tra-jectories of forest vertical structure during 0-35 years after fire and their variability.Relative height metrics(RH25,RH50,RH75,and RH98),canopy cover(CC),and plant area index(PAI)were selected as structural indicators.Structural difference series between burned areas and adjacent unburned reference areas were constructed,and a 50 km×50 km grid-based equal-weight aggregation scheme was applied.The robustness of forest structure recovery trends were evaluated using the Theil-Sen method together with spatial block resampling.Furthermore,the differences in post fire re-stroation trajectories and rates were compared by ecological zones(Great Khingan Mountains,Lesser Khingan Moun-tains,Changbai Mountains),as well as the recovery differences under varying fire severity levels.The results indicatd that post-fire forest structural recovery exhibits clear vertical stratification,with mid-canopy height(RH50)showing the strongest recovery signal,an average recovery rate of approximately 0.09 m/year,and a 35-year relative recovery ratio(RRR)of about 0.33;upper-canopy and canopy-top height metrics(RH75 and RH98)also displayed significant recovery trends but with lower relative recovery ratios than the mid-canopy layer.Among canopy attributes,PAI exhibited a more pronounced long-term change signal than CC,suggesting differences in response stages and persistence among canopy properties during post-fire recovery.Fire severity had a significant influence on structural recovery,as moderate-to high-severity burned areas showed non-significant recovery trends in lower-canopy height and canopy attributes,with substan-tially lower long-term recovery strength than low-severity burned areas.The comparison of ecological zones showed that there were significant differences in the recovery rate and relative recovery degree among the three major ecological zones,mainly reflected in the RH24,CC and PAI indicators.Among them,the recovery rate in the Changbai Mountain area was generally higher,while the restoration of the Great Khingan Mountains was more restricted in the low-level and canopy attribute indicators.This study demonstrates that GEDI LiDAR-derived structural parameters can effectively characterize long-term post-fire forest structural recovery at the regional scale,providing a scientific basis for post-fire for-est recovery assessment and forest management.