Disturbance History

The identification of disturbance events using disturbance chronologies has become a valuable tool in reconstructing disturbance history in temperate forests worldwide; yet detailed reconstructions of disturbance history and their effect on the structure and dynamics of the old-growth Nothofagus forests in the southern Patagonia are scarce. We reconstructed forest dynamics and disturbance history of an old-growth N. pumilio forest in the Toro River Valley, Santa Cruz, Argentina using dendroecological techniques. Since a variation in the disturbance regimes was expected with changing elevation, we sampled at different elevations. We found distinct differences in forest structure, dynamics, and disturbance history with changes in the elevation. The disturbance chronologies provided robust evidence that forests in the study area have been subjected to multiple disturbance events over the last 200 years. Yet, recognizing the agent of disturbance could be difficult in these montane forests and further studies are required. Moreover, disturbances might have varied from frequent, moderate-to high-severity events to less frequent and more severe events. This study represents the first of its kind for the temperate forests of Patagonia.

The driving forces of tree mortality following wind disturbances of mountain mixed European temperate forests belongs among issues not comprehensively resolved. Hence, we aimed to elucidate the key factors of tree resistance to historical severe disturbance events in the Boubínský Primeval Forest, one of the oldest forest reserves in the Czech Republic. By using spatially explicit tree census, dendrochronological and soil data, we study spatial and temporal patterns of past disturbances and mathematically compared selected characteristics of neighboring trees that were killed by a severe storm in 2017 and those that remained undisturbed. The tendency of trees toward falling was primarily driven edaphically, limiting severe events non-randomly to previously disturbed sites occupied by hydromorphic soils and promoting the existence of two spatially-separated disturbance regimes. While disturbed trees usually recruited in gaps and experienced only one severe release event, surviving trees characteristically regenerated under the canopy and were repeatedly released. Despite the fact that disturbed trees tended to reach both lower ages and dimensions than survivors, they experienced significantly higher growth rates. Our study indicates that slow growth with several suppression periods emerged as the most effective tree strategy for withstanding severe windstorms, dying of senescence in overaged life stage. Despite the selective impact of the Herwart storm on conifer population, we did not find any difference in species sensitivity for most characteristics studied. We conclude that the presence of such ancient, high-density wood trees contributes significantly to the resistance of an entire stand to severe storms.

The globally observed trend of changing intensity of tropical cyclones over the past few decades emphasizes the need for a better understanding of the effects of such disturbance events in natural and inhabited areas. On the Korean Peninsula, typhoon intensity has increased over the past 100 years as evidenced by instrumental data recorded from 1904 until present. We examined how the increase in three weather characteristics (maximum hourly and daily precipitation, and maximum wind speed) during the typhoon activity affected old‐growth oak forests. Quercus mongolica is a dominant species in the Korean mountains and the growth releases from 220 individuals from three sites along a latitudinal gradient (33–38°N) of decreasing typhoon activity were studied. Growth releases indicate tree‐stand disturbance and improved light conditions for surviving trees. The trends in release events corresponded to spatiotemporal gradients in maximum wind speed and precipitation. A high positive correl...

Even-age industrial forestry practices may alter communities of native species. Th us, identifying coarse patterns of species diversity in industrial forests and understanding how and why these patterns diff er from those in naturally disturbed forests can play an essential role in attempts to modify forestry practices to minimize their impacts on native species. Th is study compares diversity patterns of deadwood habitat structure and saproxylic beetle species in spruce forests with natural disturbance histories (wind and fi re) and human disturbance histories (clearcutting and clearcutting with thinning). We specifi cally examine how beetle diversity diff ers in relation to disturbance history and how beetle variation is linked to the diversity of deadwood habitats. Beetle and deadwood data were collected from thirty spruce forests in Nova Scotia and analyzed under three related diversity perspectives: alpha (diversity within local forests); beta (heterogeneity among local forests within disturbance classes); and gamma (cumulative species richness within disturbance classes). Few data support a prediction of lower alpha deadwood and beetle diversity in managed forests, or a prediction of lower gamma species richness in managed forests. Th e beta scale analysis yielded support for the following two hypotheses: (1) beetle assemblages are diff erent in forests with diff erent disturbance histories; (2) turnover of beetle assemblages is higher among naturally disturbed forests than among managed forests. Th e prediction of lower gamma diversity of saproxylic beetle species in managed forests compared to naturally disturbed forests was not supported. Th e lack of diff erences between naturally disturbed and industrial forests in structures that are characteristic of older forests (e.g., large-diameter deadwood) may relate to the presence of residual deadwood in second growth forests lingering from before clearcut harvesting. However, such residual deadwood is only an artifact that will soon decay and not be replaced. Th is suggests that the continuity of deadwood microhabitats for species that depend on old-forest structures is only short-term.

Based on the results of our own long-term experiments and the analysis of published data, the process of individual development (ontogeny) of trees and the parameters of ontogenetic stages are described. Changes in the environment-forming (edificatory) role of a tree in the course of ontogeny and upon its completion are characterized. The performance of this role leads to the formation of the following components of biogeocenosis heterogeneity: phytogenic fields of trees, gaps in the tree canopy, and windfall–soil complexes. The data concerning the interrelation of structural transformations of the plant and soil covers in the course of forest vegetation and soil formation on the primary substrate are reviewed.

Climate change is recognized as a major threat to global biodiversity and has already caused extensive regional extinction. In particular danger are the plant habitats in subalpine zones, which are more vulnerable to climate change. Evergreen coniferous trees in South Korean subalpine zones are currently designated as a species that need special care given their conservation value, but the reason for their decline and its seriousness remains unclear. This research estimates the potential land suitability (LS) of the subalpine zones in South Korea for six coniferous species vulnerable to climate change in the current time (1970–2000) and two future periods, the 2050s (2041–2060) and the 2070s (2061–2080). We analyze the ensemble-averaged loss of currently suitable habitats in the future, using nine species distribution models (SDMs). Korean arborvitae (Thuja koraiensis) and Khingan fir (Abies nephrolepis) are two species expected to experience significant habitat losses in 2050 (−59....

Improved forest management in the tropics is hampered by the limited availability of quantitative data, especially in tropical Africa. Important management parameters such as the minimum logging diameter (MLD), the associated biological rotation age (BRA) and the timing of silvicultural treatments are too often based on merchantable dimensions and state regulations instead of ecological data and tree growth. This study combines inventory data and bootstrapped tree-ring curves of natural and planted trees of the long-lived pioneer species Terminalia superba Engl. & Diels. A growth-oriented MLD was calculated, and the need and timing of silvicultural treatments was estimated based on the analysis of growth releases and suppressions. Study sites were situated in the Congolese Mayombe forest and western Ivory Coast. Tree rings from 41 natural forest trees (stem discs) and 29 plantation trees (increment cores) were measured, along with diameter and height measurements. Planted and natural forests showed considerable differences in mean growth rate and growth curves. More than 50% of the trees nevertheless reached the canopy without growth releases or suppressions, confirming that T. superba does not require intensive management. The growth-oriented MLD not only differs considerably between sites but bootstrapping revealed large differences within forest regions/types. Furthermore, volume-based MLD and BRA are on average larger than basal area-based calculations. The modified monocyclic management system is suggested, especially for planted forests with light-demanding, fast-growing tree species. One small-scale thinning during the juvenile phase is recommended before a final harvest that includes all trees above the growth-oriented MLD. The introduction of sustainable management for T. superba therefore primarily depends on forest type and cannot be generalized at the species level.

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 moun- tain 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 pre- dominated, 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 pat- tern is typical of immature plants. The virginal and generative plants of most species are uniformly dis- tributed, 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 vir- ginal 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.

Coniferous-broadleaf forests of the Russian Far East cover around 720 thousand square kilometers (Forest Complex of the Russian Far East: analytical review 2005). Such forests can include in their composition up to 30-40 tree and shrub species (with around 20 being common) and more than 70 herbaceous species (Forests of the Far East 1969). All these species demonstrate varying ecological requirements, levels of reaction to changes in growing conditions, life strategies and influence on their surroundings. The combination of topographical complexity (providing a diversity of microclimatic conditions) and the varying life strategies and ecology of woody species heightens the structural complexity and diversity of these vegetative communities.
The goal of our work was to use dendrochronology and stand mapping to clarify the role of gap dynamics in complex coniferous-broadleaf mixed forests and to determine the interconnections between stand structure and regeneration dynamics.
In the case of broadleaf-spruce-fir-Korean pine forests natural regeneration occurs due to individuals that already existed under canopy cover at the time of gap establishment (advance regeneration). While gap formation is essential for stimulating increased growth in understory and midstory trees and their recruitment to the overstory, it is not necessarily essential for the establishment of regeneration. In such forests, at the time of gap formation a complex understory “community” already exists made up of advance regeneration of various species in various life stages, much of which already has experienced several rounds of release and suppression. This fact makes the resulting growth trajectories of the released regeneration more complex and unpredictable than classical gap dynamics might suggest. The theory also does not consider the possibility that gaps can close before any of the released regeneration has recruited to the overstory, initiating a period of suppression, which shade tolerant species can survive. The suppressed regeneration will then await the next partial disturbance that sets the mosaic in motion.
Thus, during the period of increased growth (including both the period of active growth increase and the period of consistently high but gradually decreasing growth) suppressed understory trees of coniferous species can recruit into the midstory, young individuals in the midstory can recruit into the overstory, and overstory trees can intensively increase in diameter. At the same time, the establishment of gaps allows for the appearance of new regeneration in the understory. After some time the gaps will close and the understory and midstory trees will enter a period of suppression until the next partial disturbance.

This work attempts to bridge the gap between the research work done on developing the framework for measuring the sustainability of forest management and the lack of similar work on developing criteria and indicators (C&I) as a formal part of the planning system. We combine the forest ecosystem model FORRUS‐S and an analytical module for interactive visualization to analyze the spatial and temporal forecasting data and to examine those forest parameters that are related to the evaluation of forest biodiversity. The computer program package FORRUS‐S (Chumachenko et al., 2003), which has been developed for the simulation modeling of forest ecosystems dynamics, consists of a model of the natural development of a multi‐species, uneven‐aged stand, a model of exogenous influence (including silvi‐cultural activities) and a set of accessory programs (standard GIS, reference databases, modules recording input and output information, analytical module, 3D visualization module, etc.). The model utilizes the standard input data that have traditionally been used in Russian forestry research/management (Ed‐ confirm which is more accurate and delete the other) and that are available for virtually the entire Russian territory. The paper describes the results of computational experiments under different forest management scenarios (natural development, legal forestry, and forest practice with infringements) over 100 years. We discuss the results of forecast using a sample forest stand located in the Moscow region. The case study shows that FORRUS‐S, in combination with visualization and analysis of forecasting data, is an effective tool both for selecting sets of forest biodiversity indicators at the local level and for their eventual prioritization. This modelling approach is highly transparent, easy to understand, and offers a convenient environment for participatory decision making by forest managers.