Determination of long-term tropical cyclone (TC) variability is of enormous importance to society; however, changes in TC activity are poorly understood owing to discrepancies among various datasets ...and limited span of instrumental records. While the increasing intensity and frequency of TCs have been previously documented on a long-term scale using various proxy records, determination of their poleward migration has been based mostly on short-term instrumental data. Here we present a unique treering–based approach for determination of long-term variability in TC activity via forest disturbance rates in northeast Asia (33–45°N). Our results indicate significant long-term changes in TC activity, with increased rates of disturbances in the northern latitudes over the past century. The disturbance frequency was stable over time in the southern latitudes, however. Our findings of increasing disturbance frequency in the areas formerly situated at the edge of TC activity provide evidence supporting the broad relevance of poleward migration of TCs. Our results significantly enhance our understanding of the effects of climate change on TCs and emphasize the need for determination of long-term variation of past TC activity to improve future TC projections.
Aim
Understanding how natural forest disturbances control tree regeneration is key to predicting the consequences of globally accelerating forest diebacks on carbon stocks and forest biodiversity. ...Tropical cyclones (TCs) are important drivers of forest dynamics in Eastern Asia, and it is predicted that their importance will increase. However, little is known about the impact of TCs on forest regeneration.
Location
Latitudinal gradient from south Korea (33° N) to the Russian Far East (45° N).
Time period
Last 300 years.
Major taxa studied
Quercus mongolica, Abies nephrolepis and Pinus koraiensis.
Methods
We explored the effects of TC activity on canopy accession strategies derived from long‐term tree radial growth patterns along a 1,500‐km latitudinal gradient of decreasing TC activity. We analysed canopy accession strategies for > 800 trees of three widely distributed tree species by dividing them into gap trees (GTs), which established immediately after gap formation, and released trees (RTs), which accessed the upper canopy after a period of competitive suppression.
Results
We found a substantial decrease in GTs and increase in RTs proportionally along the gradient of decreasing TC activity. Pinus koraiensis and A. nephrolepis exhibited high variability in the proportions of the individual canopy accession strategies along the latitudinal gradient, whereas it was more stable for Q. mongolica. We identified the gradient of TC activity as the main driver influencing canopy dynamics and thus changes in life‐history traits for P. koraiensis and Q. mongolica, whereas maximal growth rate was the main driver for A. nephrolepis.
Main conclusions
Flexibility in growth strategies enabled the studied species to cover extensive areas and indicates that they will be able to cope with shifts in disturbance regimes induced by the poleward migration of TCs and increasing TC intensity. Our results highlight the canopy accession strategy as an ecological indicator of past disturbance activity.
Using dendroecological approach, the authors reconstructed disturbance history of a mixed Korean pine-broadleaved stand in the south of the Russian Far East. Their results show that during the last ...two centuries there were no mass disturbances, which may lead to canopy destruction and change of the tree species composition. The main drivers of natural dynamics of the stand were small- and middle-size gaps, and they determine current tree species abundance in the stand. They revealed 20-years periodicity in occurrence of trees growth releases, connected with gaps formation. The stand was formed only under natural disturbances (without fires, loggings and catastrophic disturbances) during at least 1000-1200 years.
Climate change significantly influences forest communities, even leading to their complete transformation. In the case of boreal and temperate forests, it is particularly important to understand how ...dominant tree species respond to climate changes, as they largely determine the structure of forest communities. In this study, we focus on the Jezo spruce (Picea jezoensis (Siebold & Zucc.) Carriere), which is widespread in Northeast Asia. We investigated the climate parameters affecting the radial growth of Jezo spruce and how their influence changes along environmental gradients. For the research, 500 tree cores were collected from 10 sites located at elevations ranging from 460 to 1060 m. We found a negative response of Jezo spruce radial growth to precipitation in July–August and SPEI in July of the current year, maximum temperatures in July–August and November of the previous year. On the other hand, we observed a positive response to the maximum temperatures in January of the current year. Furthermore, we established that the influence of these climatic parameters depends on local topography, with 74.3% of the variance in response values being explained by elevation, slope, and the Topographic Position Index. The results obtained demonstrate that the reaction of Jezo spruce radial growth to climate change will be complex, and the balance between negative and positive effects will depend significantly on local topography.
Climate change significantly influences forest communities, even leading to their complete transformation. In the case of boreal and temperate forests, it is particularly important to understand how ...dominant tree species respond to climate changes, as they largely determine the structure of forest communities. In this study, we focus on the Jezo spruce (Picea jezoensis (Siebold & Zucc.) Carriere), which is widespread in Northeast Asia. We investigated the climate parameters affecting the radial growth of Jezo spruce and how their influence changes along environmental gradients. For the research, 500 tree cores were collected from 10 sites located at elevations ranging from 460 to 1060 m. We found a negative response of Jezo spruce radial growth to precipitation in July–August and SPEI in July of the current year, maximum temperatures in July–August and November of the previous year. On the other hand, we observed a positive response to the maximum temperatures in January of the current year. Furthermore, we established that the influence of these climatic parameters depends on local topography, with 74.3% of the variance in response values being explained by elevation, slope, and the Topographic Position Index. The results obtained demonstrate that the reaction of Jezo spruce radial growth to climate change will be complex, and the balance between negative and positive effects will depend significantly on local topography.
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•We reconstructed disturbance history of old-growth Korean pine-broadleaved forest.•We performed analysis of spatial population structure for the dominant tree species.•Only low- and ...medium-intensity disturbance events took place over two centuries.•There are regeneration waves of tree species associated with the disturbances.•Current disturbance regime promotes dominant tree species coexistence in the stand.
We used a dendroecological approach to reconstruct the disturbance history of the old-growth Korean pine (Pinus koraiensis Siebold et Zucc.)-broadleaved forest in the southern part of the Sikhote-Alin mountain range (Southeastern Russia). We also performed a point pattern analysis to study the population structures of the five dominant tree species, and our findings demonstrate that there were no intense, stand-replacing disturbances from 1800 to 2000. Low- and medium-intensity disturbance events predominated, and the most probable cause of these disturbances was windthrow due to strong winds. The age structure of the coniferous species indicates recruitment continuity, so the stand is unevenly aged, but regeneration waves associated with the disturbances can be distinguished. The population structure of the dominant species is characterized by similar features, and the aggregate distribution pattern is typical of immature plants. The virginal and generative plants of most species are uniformly distributed, but the generative individuals of some species tend to be hyperdispersed over a small spatial scale. The advanced regeneration pool is mostly composed of immature plants of both shade-tolerant coniferous and light-demanding deciduous species, which confirms that immature deciduous species are characterized by significant shade tolerance, although to a lesser extent than coniferous plants. In virginal plants, light demand is greater for both coniferous and deciduous species. The populations of the dominant species are stable, so the current disturbance regime promotes the coexistence of shade-tolerant and light-demanding species but affects the abundance of the various plant species in the stand.
•We described plant pattern evolution for tree species in Korean pine forest.•Plant pattern transforms from aggregated for young plants to random for older ones.•For all species shade-tolerance of ...plants decreases with their development.•Gap formation is stochastic along of several decades.•After being filtered by gaps only randomly distributed plants reach the stand canopy.
We used point pattern analysis (pair-correlation function, K2 function, distance to kth neighbor Dk, and spherical contact distribution function Hs) to describe the process of plant pattern formation for five dominant tree species with different life strategies in a mixed-forest stand with Korean pine (Pinus koraiensis Sieb. et. Zucc.) in the southern part of the Sikhote-Alin mountain range (southeastern Russia). We subdivided each species pattern using an ontogenetic classification of individuals: immature, virginal, and generative. We also analyzed stump pattern structure, which marks canopy gap formation locations in recent decades. We also studied the shade tolerance changes of pre-generative plants during their development. As a result, we found similarities between the processes of pattern transformation for the different species. Namely, they transform from pronounced aggregated distributions of plants at several spatial scales (immature plants) to a random pattern (middle-aged and old generative plants). This transformation of pattern structure occurs because the immature plants accumulate under a canopy and require significantly improved light conditions that can only be found in gaps to transition into the virginal and young-generative stage. In turn, the process of gap formation is stochastic, and the stand is characterized by a low-intensity disturbance regime. Thus, the pre-generative plant patterns are filtered by randomly formed gaps, and thus only individual randomly distributed plants reach the middle-aged and old generative ontogenetic states.
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