Resistance and Resilience of Hyrcanian Mixed Forests Under Natural and Anthropogenic Disturbances

Abstract

Biological disturbances are integral to forest ecosystems and have pronounced effects on forest resistance, resilience, and diversity. The Hyrcanian mixed forest, in northern Iran, is at risk of declining resistance, resilience, and diversity due to ongoing pressure from land use change, harvesting, and biological disturbances. We analyzed the resistance and resilience of this area under two biological disturbances (i.e., oak charcoal fungus, Biscogniauxia mediterranea, and alder leaf beetle, Galerucella lineola) and in concert with proposed harvesting. We used a simulation modeling approach whereby we simulated 12 combinations of biological disturbances and harvesting scenarios using the LANDIS-II landscape change model. We estimated the correlation between forest resistance and resilience and tree species diversity to harvesting and biological disturbance. We analyzed the full species composition and age class for 30 and 100 years after disturbances in order to assess resistance as the change in species composition over time. We considered resilience as the ability to recover from a disturbance back to a similar initial state. Results indicate a positive effect of biological disturbances and harvesting on diversity. Our simulations resulted in a negative relationship between diversity-resistance and diversity-resilience within high diversity areas. Our simulation of the Hyrcanian forest reveals that harvesting and biological disturbances, as tested, fulfill the goal of maintaining forest diversity. However, increasing diversity does not always follow by increasing forest resistance and resilience. Scenarios with oak charcoal fungus, both with and without harvesting indicate the lowest decrease in resilient and resistant.

New records of springtails (Hexapoda, Collembola) for Iran from the Bula Hyrcanian forest

“…Recognition of these forests as a World Heritage site will increase the worldwide popularity of these forests, which additionally can enhance the realization of the people in the region of their outstanding heritage through awareness raising and exchange of experiences with other world heritage sites (Tohidifar et al, 2016;IUCN Evaluation Report, 2023;Homami Totmaj et al, 2020). UNESCO World Systematics 2024  10 (1) Heritage List in Hyrcanian forests are located in 15 regions including Golestan National Park, Abr Forest, Jahan-Nama Forest, Bula Forest, Alimestan Forest, Vaz Forest, Kojur region of Nowshahr, Chahar-Bagh region of Chalus, Khoshkeh Daran forest, Gasht-e Rudkhan, Siahrudbar of Gilan, Lisar protected area with a rich plant and animal variety (Vakili et al, 2021;Nourzad Moghaddam et al, 2018;Homami Totmaj et al, 2020). These forests are one of the major glacial refugia arcto-tertiary forest vegetation where some tertiary relics survived the Ice Age and developed numerous endemic taxa of flora and fauna (Vakili et al, 2021).…”

“…UNESCO World Systematics 2024  10 (1) Heritage List in Hyrcanian forests are located in 15 regions including Golestan National Park, Abr Forest, Jahan-Nama Forest, Bula Forest, Alimestan Forest, Vaz Forest, Kojur region of Nowshahr, Chahar-Bagh region of Chalus, Khoshkeh Daran forest, Gasht-e Rudkhan, Siahrudbar of Gilan, Lisar protected area with a rich plant and animal variety (Vakili et al, 2021;Nourzad Moghaddam et al, 2018;Homami Totmaj et al, 2020). These forests are one of the major glacial refugia arcto-tertiary forest vegetation where some tertiary relics survived the Ice Age and developed numerous endemic taxa of flora and fauna (Vakili et al, 2021).…”

Impacts of Forest Management on the Biodiversity and Sustainability of Carya dabieshanensis Forests

“…The stability of plant communities is a comprehensive reflection of their structures and functions, which mirrors the anti-disturbance capacity of forests and their ability to recover community structures after further disturbances. Thus, the investigation of community stability is useful toward understanding the status quo and succession law of vegetation communities [6,7].…”

Fine-scale topographic influence on the spatial distribution of tree species diameter in old-growth beech (Fagus orientalis Lipsky.) forests, northern Iran

“…The catena topography of this region influences both regional and micro-climate conditions which can have a large effect on tree species distribution and environmental processes 5 . The management objective of Hyrcanian forests controlled by the Iranian Forests, Range, Watershed, and Management Organization (FRWO) is to maintain the current forest stand composition, protect its level of biodiversity and avoid any shift in the composition of commercial forest types 7 ( https://whc.unesco.org/en/list/1584 ).…”

“…Studying the distribution of tree species within this topographically complex landscape will facilitate more accurate ecosystem evaluation, e.g. as new pathogens potentially cause selective mortality of trees or new management scenarios are considered for increasing resistance and resilience against natural and anthropogenic disturbances 7 .

Figure 1 Location of the study area ( a ), and a diagram illustrating orientation, and the shape of the two major catena types, as well as their approximate locations in the study area ( b ).

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