Hyrcanian Forests Research Articles

Diverse endophytic fungi colonise wild endemic grasses and sedges in Hyrcanian Forests

Fungal endophytes were identified associated with leaves, stems and roots of wild grasses (Poaceae) and sedges (Cyperaceae) residing in Hyrcanian Forests, some of the most unique and unspoiled forest systems in the world. The plants grew in two climatically-distinct regions of Golestan and Semnan provinces of Iran. Endophytic fungi isolated from these plants were categorised into 27 morphogroups based on physical attributes measured in vitro. Sequence diversity was estimated from the internal transcribed spacer (ITS) region of the ribosomal DNA gene. Of the 53 isolates characterised in this study, identification of only one isolate was conclusive at the species level. Twenty-eight isolates were identified to the level of genus, belonging to seven families and six orders, six isolates to the level of family, 13 at the level of order, one to the super family, and four to the subphylum. Members of the genera Fusarium and Alternaria, and of the families Necteriaceae, Pleosporaceae and Trichocomaceae were the most abundant fungal endophytes identified. Several endophytes resembled those of fungal pathogens. This study advances our understanding of endophytic fungal communities of indigenous grasses and sedges in Hyrcanian Forests.

The Response of Soil Physicochemical Properties in the Hyrcanian Forests of Iran to Forest Fire Events

When forest fires occur, highly complex effects on soil properties and hydrological processes are activated. However, in countries such as Iran, these consequences are not widely studied and there is a lack of studies. Therefore, the main aim of this study was to investigate the effects of wildfire on soil quality characteristics in a representative forest area located in the Hyrcanian forests, specifically, in the Zarrinabad watershed of Sari. For this purpose, four different sites, including unburnt natural (UNF), burned natural (BNF), unburnt plantation (UPF), and burned plantation forests (BPF) were selected. Soil sampling was performed at each site using the random, systematic method at a depth from 0 to 30 cm. To investigate the effects of fire on physical and chemical properties indicators, 10 plots with dimensions of 0.5 × 0.5 m were placed at a distance of 1.5 m from each other at each site. Soil samples were transported to the laboratory and their physical and chemical properties were determined. The results showed that the percentage of sand, silt, aggregate stability, soil hydrophobicity, organic carbon, organic matter, soil total nitrogen, absorbable potassium and phosphorus, electrical conductivity, and pH, increased significantly when the soil surface is burned (p ≤ 0.01, p ≤ 0.05). However, clay percentage, initial, final, and average infiltration in the burned areas showed a decreasing trend in comparison with other forest statuses. Furthermore, no significant effects were observed on the true and bulk density, porosity, and soil moisture (p ≥ 0.05). These findings demonstrate that forest fire effects in Iran must be considered as a key topic for land managers because soil properties and hydrological processes are drastically modified, and land degradation could be irreparably activated.

Improving species distribution models for dominant trees in climate data-poor forests using high-resolution remote sensing

Species distribution models (SDMs) are useful for predictive and explanatory purposes, allowing biologists to identify how human and environmental factors influence distributions of plants and animals. Lack of high-resolution climatic variables is one of the challenges for accurately predicting distributions of organisms at local or landscape scales. This study used SDMs to predict four dominant tree species distributions in northern Iran temperate forests (400km2 area) using high-resolution Sentinel-2 data (20 m) and topographic variables. We divided the explanatory variables into four datasets with increasing complexity of Sentinel-2 data and modelled distributions using four statistical and machine learning algorithms: random forest (RF), generalized boosting model (GBM), generalized linear model (GLM), and generalized additive model (GAM). Our results suggested differences in the predictive performance of the four algorithms. We found the most complex dataset, including topographic variables, Sentinel-2 bands, and vegetation and soil indices, gave the best fit for the four tree species, improving the accuracy of models for the different species between 5 and 16%. We then selected the most complex dataset to produce an ensemble model of the modeling algorithms where evaluation criteria were varied for tree species. Our result showed that the performance of SDMs improved using different satellite remote sensing data including raw bands, topographic variables and indices in the Hyrcanian forest, northern Iran. Elevation was a more significant variable than Sentinel bands and Sentinel vegetation indices variables for predicting the tree species distributions. With the Hyrcanian Forest included in this study region of northern Iran recently declared a UNESCO World Heritage site, a key result of our improved species distribution maps for these four dominant tree species is to support conservation management of forest biodiversity in this region.

Localization and Prioritization of Ecovillages Indices in Hyrcanian Forest (Case Study: Ecovillages of Darabkola Forests)

Localization and Prioritization of Ecovillages Indices in Hyrcanian Forest (Case Study: Ecovillages of Darabkola Forests)

Investigation the Effectiveness of Protected Areas in Hyrcanian Forests, Iran

Investigation the Effectiveness of Protected Areas in Hyrcanian Forests, Iran

Acer velutinum Bioss. (velvet maple) seedlings are more tolerant to water deficit than Alnus subcordata C.A. Mey. (Caucasian alder) seedlings

Drought stress is a major environmental factor limiting plant growth. Selection of drought-tolerant plants is of critical importance in vegetation restoration and forestation programs. Alnus subcordata and Acer velutinum are two valuable, dominant, and endemic species in the Hyrcanian forests. There are fast-growing species and significant diffuse-porous hardwood in afforestation and reforestation. One-year old seedlings of both species were exposed to four water shortage treatments (100, 75, 50 and 25% of field capacity (FC) chosen as control, mild, moderate, and severe) for 12 weeks. Thereafter, their morphological characteristics such as height and basal area, total and organs biomass (root, stem, and leaf), leaf area (LA), specific leaf area (SLA), leaf area ratio (LAR), as well as physiological and biochemical characteristics such as relative water content (RWC), content of chlorophyll, free proline and malondialdehyde (MDA), and superoxide dismutase (SOD) and peroxidase (POD) activity were measured. The results showed that when exposed to reduced water availability, plants’ height, basal diameter, total and organs biomass, LA, LAR, RWC and chlorophyll content decreased, but their proline concentration, MDA content, SOD, and POD activity increased in both species. The root to shoot ratio (R/S) and root mass ratio (RMR) increased at 50 and 25% FC treatments in A. subcordata, whereas no significant difference was found in A. velutinum under drought treatments. SLA increased significantly at 50% FC in A. velutinum and decreased in A. subcordata under drought treatments compared to control treatment. A. velutinum showed more proline content, RWC, POD, and lower increase in MDA content than A. subcordata under moderate treatment. Therefore, A. velutinum appears to possess a better mechanism to cope drought stress. The drought tolerance of A. velutinum may enhance its potential for climatic adaptations under drier conditions with the ongoing climatic change.

Modeling Tree Growth Responses to Climate Change: A Case Study in Natural Deciduous Mountain Forests

Climate change has significant effects on forest ecosystems around the world. Since tree diameter increment determines forest volume increment and ultimately forest production, an accurate estimate of this variable under future climate change is of great importance for sustainable forest management. In this study, we modeled tree diameter increment under the effects of current and expected future climate change, using multilayer perceptron (MLP) artificial neural networks and linear mixed-effect model in two sites of the Hyrcanian Forest, northern Iran. Using 573 monitoring fixed-area (0.1 ha) plots, we measured and calculated biotic and abiotic factors (i.e., diameter at breast height (DBH), basal area in the largest trees (BAL), basal area (BA), elevation, aspect, slope, precipitation, and temperature). We investigated the effect of climate change in the year 2070 under two reference scenarios; RCP 4.5 (an intermediate scenario) and RCP 8.5 (an extreme scenario) due to the uncertainty caused by the general circulation models. According to the scenarios of climate change, the amount of annual precipitation and temperature during the study period will increase by 12.18 mm and 1.77 °C, respectively. Further, the results showed that the impact of predicted climate change was not very noticeable and the growth at the end of the period decreased by only about 7% annually. The effect of precipitation and temperature on the growth rate, in fact, neutralize each other, and therefore, the growth rate does not change significantly at the end of the period compared to the beginning. Based on the models’ predictions, the MLP model performed better compared to the linear mixed-effect model in predicting tree diameter increment.

Triplax sulphuricollis Reitter, 1887 from the Hyrcanian forests of Iran recognized as a valid species by morphology and barcoding (Coleoptera: Erotylidae)

The status of Triplax collaris sulphuricollis Reitter, 1887 is reevaluated based on recent records from the Hyrcanian forests in northern Iran. Morphological features and barcoding support separate species status as Triplax sulphuricollis Reitter, 1887, new status. Morphological characteristics include an orange-yellow antennal club and elytral punctation arranged in striae. Triplax sulphuricollis is associated with oyster fungi of the genus Pleurotus growing on dead wood of deciduous trees.

A preliminary checklist of saproxylic beetles (Coleoptera) in the Hyrcanian forests of Iran, with distributional data

Saproxylic beetles play a vital role in conservation as indicators of the status of unmanaged forests. In light of the concern regarding the adverse impact of anthropogenic pressure on biodiversity, an essential step in forest conserva-tion strategy is the identification of saproxylic beetles. The Hyrcanian forests are a unique remnant of natural broadleaf temperate forests, with an evolutionary history that can be traced to the Tertiary and a high diversity tree species. Here we present the first checklist of saproxylic beetles in the Hyrcanian forests, including 398 species of saproxylic beetles, belonging to 207 genera and 46 families, identified by us. Based on our results and literature data, at least 670 saproxylic beetles occur in the Hyrcanian forests. The bias in our results towards some families supports the view that the detection of additional species can be expected, particularly from the forests with a greater diversity of tree species.

Long-term changes in the inversion chromosomal polymorphism: Drosophila subobscura population from Rasht (north of Iran)

Drosophila subobscura is characterized by a rich chromosomal polymorphism for inversions. Many inversions are adaptive to global warming and can be classified as 'warm' or 'cold' adapted. However, most studies were carried out from European populations located in the central area of the species distribution or from American colonizing populations. For this reason, we aimed to analyse the isolated and marginal Rasht population, located in the Hyrcanian forests area (Iran). The chromosomal polymorphism for inversions was compared with the previous Rasht samples (Rasht I and II) obtained 57 years ago. This polymorphism has changed based on the inversion composition and frequencies. Interestingly, the polymorphism for inversions was scarce and similar to that of Madeira, an isolated Atlantic island. Likely, this similarity is a consequence of the marginal location and isolation of the Rasht population. Also, the chromosomal thermal index (CTI) was 0.445, showing a significant increase over those from Rasht I (0.184) and II (0.210). All these observations were in agreement with the global warming expectations. Moreover, the CTI was also computed for Russian Caucasus and Turkish populations collected more than 40 years ago to better understand the adaptive potential of D. subobscura and to study the similarity between populations of different geographic areas. In summary, the inversions of D. subobscura also changed in marginal and isolated populations in agreement with the global warming expectations, and an open question is to know where is the threshold for this evolutionary change.

Ecological niche modeling uncovered that Holocene warming is responsible for disjoint distribution of Zamenis persicus (Werner, 1913) (Squamata: Colubridae)

Zamenis persicus (Werner, 1913) is near-endemic to the “South Caspian Circumscripation”, which is covered by Hyrcanian forests, a critical biodiversity hot spot in western Eurasia in terms of their origin and evolutionary history. The present study aims to evaluate the changes in the distribution of Zamenis persicus in the past, current, and future periods. For this purpose, 51 points of presence of species and eight climatic variables were analysed with Maxent software. We used four presence points outside the typical habitat of the species to test the presence of this species in the past in those areas. The most important variable affecting the distribution of the species is annual precipitation. The distribution of this species was more extensive in the past than today and included four test points, Miyaneh, Qom, Sabzevar, and Sarakhs. It seems that with the decline of Hyrcanian forests in the past, this species has shifted to higher latitudes. Predictions also forecasted a possible shrinkage of this species’ range. Climate change and habitat change can have a more severe effect on the remaining habitats of this species.

Relationship between vegetation characteristics and Lepidoptera diversity in the Hyrcanian forest, Iran (Insecta: Lepidoptera)

The patterns of diversity of Lepidoptera and its relationship with environmental characteristics in the Hyrcanian forests of northern Iran have not been investigated so far, while such studies are extremely effective in restoring forest biodiversity. This study aimed to assess the relationships between vegetation characteristics and the abundance and diversity of Lepidoptera in Darabkola forest, Sari district (Mazandaran province, northern Iran). Light trapping yielded a total of 474 exemplars representing 84 species and belonging to 16 families. 31 plant species belonged to 28 genera and 23 families were recorded of three distinct forests in the region. The total number of plant species and Fisher’s α showed the significant difference. The regression analysis indicated that the Lepidoptera abundance was correlated with basal area, diameter at breast height and tree density, although a significant relationship was not observed between plant characteristics and Fisher’s α of Lepidoptera. The lack of a significant relationship between plant diversity and the abundance and diversity of Lepidoptera represents the weak role of plant diversity in creating diversity patterns in forest ecosystems.

Are morphological characteristics of Parrotia (Hamamelidaceae) pollen species diagnostic?

Parrotia persica is one of the most notable endemic relict tree species growing in the Hyrcanian forest at the southern Caspian Sea. The recent discovery of sibling species Parrotia subaequalis, occurring in the temperate forests of south-eastern China, offers the opportunity to compare their morphology and ecological preferences and to dig deeper into the paleophytogeographic history of the genus from a perspective. Since pollen morphology of these species would be essential to unravel the origin and evolution of these Arcto-Tertiary species, the present study aimed to investigate whether it is possible to segregate pollen from these two species. Therefore, a detailed combined light- and scanning electron microscopy-based pollen-analysis of each taxon was conducted, the pollen was described, measured, and compared using statistical approaches and principal component analyses to establish unbiased results. The correlation-based principal component analysis achieved for each species shows an overall good superposition of pollen grains measured in equatorial and polar views in the first principal plane, revealing that the P. persica pollen is morphometrically as homogeneous as that of P. subaequalis. Then, the significant difference, mainly driven by lumen density, has been highlighted between the two species. Ultimately, the cross-validation of the resulting two-species linear discriminants classifier shows that based upon this reference dataset, (sub)fossil pollen grain can now be confidently assigned to either of the two species with an 85.8% correct-assignment rate. This opens new doors in the affiliation of fossil Parrotia pollen and suggests that previous pollen records need to be revised.

Effects of plot size on assessment of tree species diversity in Caspian forests of Iran

Abstract. Mirzazadeh A, Pourbabaei H, Daryaei MG, Bonyad A. 2022. Effects of plot size on assessment of tree species diversity in Caspian forests of Iran. Biodiversitas 23: 4879-4886. Tree species diversity is important to forest managers because any management that reduces tree species diversity may greatly reduce commercial benefits. Therefore, control over tree species diversity is an important aspect of hardwood forest management. An efficient and quick survey method is needed to facilitate the assessment of tree species diversity in forest stands. In this study, the effects of plot size on the assessment of tree species diversity were compared in the uneven-aged hardwood stands in the Hyrcanian forests of Iran. There were selected 50 hectares of these forests representing the regional forests. Sampling procedures were carried out on concentric lozenge plots with different sizes, including 400, 800, 1000, 1200, 1600, 2000, 2500, and 5000 m2 in the dimensions of 150×150m. For each plot, the type of the species and the number of trees were recorded. Shannon-Wiener (H’), Simpson (1-D), Mc-Arthur (N1), Hill (N2), Camargo (E'), Simpson (E1/D), Nee (EQ), Smith-Wilson (Evar), Menhinick (R2), Margalef (R1) indices were used to estimate of tree species biodiversity. The precision and cost criteria (E%2× T) were applied for a better evaluation of different plot sizes. The obtained inventory error values showed that Hill (diversity), Camargo (evenness) and Menhinick (richness) indices had the lowest inventory error in the different plot sizes. Also, the lowest value of inventory error in diversity, evenness and richness indices were related to plot sizes of 2500, 5000, and 5000 m2, respectively. Based on the obtained results of diversity and evenness indices, there was a significant difference between the different plot sizes and different indices. The results showed that the lowest value of E%2×T for diversity, evenness and richness was related to Hill (800 m2), Camargo (1000 m2), and Menhinick (400 m2). The finding results revealed that plot size had a significant effect on tree species’ evenness.

Habitat and river riparian assessment in the Hyrcanian Forest Ecoregion in Iran: providing basic information for the river management andrehabilitation.

The Hyrcanian Forest holds broad leaf forest remnants dating back to the early Cenozoic Era, which once covered a vast area of the North Temperate Zone. Today, many rivers within this region have been altered by human activities and urgently need rehabilitation. In this regard, 35 wadeable rivers including 14 reference and impacted sites were investigated to determine how different human pressures altered riverine landscapes and habitats. Hence, five common human pressures (agriculture, urbanization, aquaculture, dams, aggregate mining) were identified, then the riverine landscape and habitat condition of each site were assessed. At each site, 17 aquatic, riparian, and terrestrial features, including abiotic and biotic substrate types, were investigated. The number and ratio of pressure-influenced channel features and substrate types differed from those in reference sites. Reference sites were dominated by microlithal, mesolithal, and macrolithal abiotic substrates and large wood, algae, and coarse particulate organic matter biotic substrates. Urbanized sites were most altered and dominated by single channels, steep unvegetated riprap banks, and algae substrate. The results provide valuable information for managers and decision-makers to restore riverine ecosystems considering the impaired parameters resulting from human pressures.

New records of Empididae and Hybotidae (Insecta: Diptera) from Hyrcanian forest in Iran and Azerbaijan

The genus Dolichocephala Macquart, 1823 of the family Empididae is recorded for the first time from Iran and Azerbaijan, including one species D. monae Joost, 1981. A neighbour-joining tree based on genetic divergences on the CO1 gene within nine species of Dolichocephala is provided. In addition, the genus Oropezella Collin, 1926 of the family Hybotidae (one species O. sphenoptera (Loew, 1873)) and two species of the subgenus Empis s. str. of the genus Empis Linnaeus, 1758 (E. (E.) earina Collin, 1960 and E. (E.) temryukiensis Kustov et Shamshev, 2013) of the family Empididae are reported for the first time from the territory of Iran. The female of E. (E.) temryukiensis is described for the first time.

Response to Global Warming of Eichwald's Toad,Bufo eichwaldiLitvinchuk, Borkin, Skorinov and Rosanov, 2008 (Anura; Amphibia) in Iran and Azerbaijan

Global warming is considered to be a major threat to biodiversity and to have an erosive effect on the survival of endangered species. Amphibians are known as a vulnerable group of vertebrates that live and reproduce in both terrestrial and aquatic habitats. The subtropical regions of the world are among the land areas where amphibians will suffer the most from climate change. In the present study, the effect of climate change onBufo eichwaldiinhabiting Hyrcanian forests was investigated. According to our results, the lowest temperature in the coldest season is the most important variable for the presence of this species. Due to the beginning of reproductive activity and mating taking place in late January until the end of February, this variable will have a direct effect on the rate of breeding and thus on the conservation of this species, because the species can find a new suitable area outside of high humanisation and increase its chance of successful breeding. Of course, climate change will cause the average annual temperature to rise by 2070, and this will favour the early onset of reproduction. Therefore, according to the analysis and scenarios considered in this study, global warming cannot have a negative effect on the toad species. However, a careful assessment of the status of other competing species in conjunction with the Talysh toad could provide a better explanation of the impact of climate change.

The impact of climate change on the future geographical distribution range of the endemic relict tree Gleditsia caspica (Fabaceae) in Hyrcanian forests

The Caspian locust (Gleditsia caspica) is an endemic relict tree that occurs in Hyrcanian forests. Many of its habitats have been destroyed in the last half-century. This study was performed to map past geographic distributions and estimate the suitable areas and potential risks of remaining populations under future climate change. Eight bioclimatic scenarios (one with current conditions, three with future climates, and four with past conditions) were tested using the maximum entropy algorithm. The most significant factors influencing the distributions of G. caspica were precipitation in the driest month and temperature seasonality. Even under the most optimistic model (RCP2.6), many stands of G. caspica may become endangered in the eastern and central parts of the range, and the distribution of this species will probably shift to the west of the Hyrcanian forest area. Considering the increasing destruction of habitats of this species due to human activities and the expected negative effects of climate change in the future, it is recommended that nature reserves be established to protect the habitat of G. caspica. Additionally, ex situ conservation strategies, such as storing seeds using cryopreservation techniques, can ensure the long-term survival of this species in the future.

Habitat suitability, core habitats and diversity hotspots for the conservation of the mustelid species in Iran

The process of habitat loss and fragmentation is inevitable with increasing human activities, necessitating conservation for the areas with the highest priorities (i.e., biodiversity hotspots). This study aimed to predict the core habitats of the eight mustelid species (family: Mustelidae) in Iran and detect mustelid diversity hotspots based on the highest species richness of these species to compare them with available conservation areas (CAs). Accordingly, habitat suitability modeling was carried out for each mustelid species through an ensemble approach, and species richness and mustelid diversity hotspots were determined by overlaying the predicted core habitats. The results revealed that the highest richness of the mustelid species was six species for the overlaid map of the modeled core habitats. The main mustelid diversity hotspots were along the Alborz Mountains and the Hyrcanian forest of northern Iran. There were some other hotspots along the Zagros Mountains in western Iran. CAs protected less than half of mustelid diversity hotspots, which means that wildlife managers should take into consideration the conservation action plan for the mustelid species in Iran. Besides, it is necessary to expand available CAs or establish new-targeted CAs according to mustelid diversity hotspots.

Susceptibility of Cydalima perspectalis (Lepidoptera: Crambidae) larvae to some reduced-risk insecticides in laboratory bioassays

Box tree moth (BTM) Cydalima perspectalis (Walker, 1859) is the most harmful pest of different boxwood species in Europe and Asia including Caspian boxwood Buxus hyrcana in the Hyrcanian forests of Iran. Accessible and effective eco-friendly insecticides are required for the pest control. Thus, susceptibility of 2<sup>nd</sup> and 4<sup>th</sup> instar larvae of BTM to commercial formulation of Bacillus thuringiensis (Bt), two plant extract formulations, Bio1<sup>®</sup> and Matrine<sup>®</sup>, and three insect growth regulator (IGR) insecticides, chlorfluazuron, chromafenozide and diflubenzuron were investigated in laboratory bioassay. Except for diflubenzuron, significant mortality of both instar larvae was observed. At the endpoint of the experiments (96 h), 75.2–90% of second and 80–85% of fourth instar larvae had already died, as a result of feeding on leaves treated with the highest concentration of the insecticides. Furthermore, based on Probit analysis, Matrine<sup>®</sup> exhibited the highest efficiency (lethal concentration LC<sub>50</sub> = 2.87 μL·L<sup>–1</sup>) on 2<sup>nd</sup> instar larvae and followed by Bio1<sup>®</sup> (8.07 μL·L<sup>–1</sup>), chlorfluazuron (173.3 μL·L<sup>–1</sup>) and Bt (326.3 mg·L<sup>–1</sup>). The LC<sub>50</sub> of Matrine<sup>®</sup> and Bt for 4<sup>th</sup> instar larvae were 1.75 μL·L<sup>–1</sup> and 335.8 mg·L<sup>–1</sup>, respectively. Our study revealed that Matrine<sup>®</sup> and chromafenozide could be alternatively used against BTM in situations where there is a permission and need to use insecticides.