Post‐fire vegetation recovery at forest sites is affected by permafrost degradation in the Da Xing'an Mountains of northern China

Abstract

Question Vegetation recovery and succession patterns after fire are not completely explained by the interactions of climate, disturbance, and species pool. Site‐specific factors can substantially change vegetation succession. We hypothesize that on sites exposed to fire and surface permafrost degradation, successional trajectories will produce different species assemblages than typical post‐fire succession. Location Da Xing'an Mountains, northern China. Methods Vegetation and environmental data were collected at eight sites of past natural wildfire events. These sites represented different topographical situations, with four sites on slopes (lacking surface permafrost) and four sites in valleys (with surface permafrost). Three plots were established on each site, representing three different fire presence zones (burned, ecotone and unburned areas), giving a total of 24 plots. We used non‐metric multidimensional scaling (NMS) to describe post‐fire vegetation recovery at different sites and multi‐response permutation procedures (MRPP) to test our hypothesis. Results The variation in dates of last fire was similar between the slope and valley sites. Slope sites that had been burned prior to 2003 had recovered to a composition similar to unburned sites by the time the study was conducted in 2017. However, none of the burned valley sites had fully recovered, even those exposed to fire in 1986, suggesting that the surface permafrost conditions affected the recovery pattern of vegetation. On burned valley sites, shrub species that are tolerant of saturated soils had become dominant and the number of tree saplings and seedlings became significantly lower than on the slope sites. Conclusion The interaction of fire and topographic site type (through the influence of surface permafrost degradation) was revealed as a primary factor affecting species composition and tree density of post‐fire communities. On valley sites, melting of the surface permafrost after fire caused a failure of tree recruitment and prompted shrub species tolerant of saturated soils to become dominant.

Dynamic Characteristics of Vegetation Change Based on Reconstructed Heterogenous NDVI in Seismic Regions

“…NDVI is a measure of the "greenness" of the vegetation and is correlated with leaf area, leaf biomass [14][15][16], canopy cover [17][18][19][20], and chlorophyll content [21][22][23], and is strongly related to photosynthetic capacity [24][25][26], fluorescence [27,28], and Net Primary Productivity [29][30][31][32]. NDVI has been used to describe ecosystem status, condition, disturbance, and change [33][34][35][36][37][38]. NDVI can be retrieved from many satellite instruments, including the Satellite for Observation of Earth VEGETATION (SPOT-VGT), the Moderate Resolution Imaging Spectroradiometer (MODIS), the Landsat Thematic Mapper (TM), Sentinel 2 Multispectral Instrument (MSI), and the Project for On-Board Autonomy Vegetation (PROBA-V).…”

Spatiotemporal Distribution Characteristics of Fire Scars Further Prove the Correlation between Permafrost Swamp Wildfires and Methane Geological Emissions

“…On the other hand, with the continuous warming of the climate, the recovery ability of the permafrost temperature field is diminishing, and fires can have a compounding effect that accelerates the existing rate of permafrost degradation [57]. When the upper limit of permafrost drops to a critical depth, the overlying peat layer will not completely refreeze in the following winter, leading to further development of the active layer and formation of the thawing interlayer [15,58]. The slow recovery mechanism of permafrost cannot keep up with the effects of warming and fires.…”

Burned vegetation recovery trajectory and its driving factors using satellite remote-sensing datasets in the Great Xing’An forest region of Inner Mongolia

“…A considerable amount of literature on post-fire vegetation recovery has been published. Though these works studied a variety of forest ecosystems (Bartels et al 2016;Hao et al 2022), fewer works defined the different succession stages (Meng et al 2015;João et al 2018;Viana-Soto et al 2020), and few have been applied to the Great Xing'An Range (Shi et al 2019;Guo et al 2021). Our study focuses on classifying and identifying vegetation recovery in burned areas at different stages and their driving factors in the Great Xing'An Range.…”