Soil functional indicators in a mountain forest-rangeland mosaic of northern Iran

Abstract Soil plays an essential role in providing ecosystem services, especially in mountain ecosystems which are often considered as fragile and sensitive systems and commonly consist of a mosaic of forest and rangeland plant communities. The relationship between above-ground plant cover and the properties of soil organic and mineral layers in mountain areas are rarely studied. This research aimed to assess the effect of different land covers (i.e. forest, forest-rangeland ecotone, and rangeland) on soil functional indicators, i.e. fertility and biological activities, in the Hyrcanian region of northern Iran. We hypothesized that (i) the presence of tree cover enhances soil fertility and biological activities and creates hot spots (islands) of soil functional indicators especially in the topsoil, (ii) litter quality and organic matter fractions are the drivers for activities of soil organisms, nutrient cycles and transformation processes in mountain ecosystems. Litter (O-horizon including L, F and H layers) and mineral soil samples (in two separate depths of 0–10 cm and 10–20 cm) were taken using iron frames (30 × 30 cm). In total, 45 litter and 90 soil samples were transferred to the laboratory. Soil characteristic especially in the 0–10 cm depth, litter carbon (C), nitrogen (N) and C/N ratio were significantly affected by different land covers showing the maximum of soil organic C and microbial activity under forest. Our findings showed that the studied land covers, as well as litter and soil properties can be separated by PCA output. The first and second axes, accounted more than 50% of the explained variance in each of the studied soil depths. Soils with a better quality of litter (i.e. lower C/N ratio), higher values for organic matter fractions, soil fertility indicators and soil biological activities can be attributed to the forest. In contrast, positions of low soil fertility indicator values and biota abundance were imposed by forest-rangeland ecotone and rangeland. Although each land cover plays a prominent ecological role and takes its place in the evolutionary process, forests are essential because of their capacity to store and transform carbon and nutrients and to create hotspots identified by functional soil indicators. Based on our findings, soil functions decreased ranked in the order forest > forest-rangeland ecotone > rangeland, which can be assigned to the lower density of trees, and the amount of litter mass and litter quality. It can be concluded that tree covers have a prominent role in increasing soil functions, which should be given special consideration in the restoration of degraded mountain ecosystems

Impact of Land Cover Changes on Reducing Greenhouse Emissions: Site Selection, Baseline Modeling, and Strategic Environmental Assessment of REDD+ Projects

peer reviewedReducing emissions from deforestation and forest degradation (REDD+) is way key to reduce the emission of greenhouse gases (GHGs) while also protecting vulnerable forest ecosystems. The purpose of this study was to recognize suitable areas for REDD+ Programme projects and calculate the reduction in CO2 emissions through the prevention of forest cover degradation in the Central Hyrcanian forests. For this purpose, the cover changes of the Central Hyrcanian forests were assessed using LANDSAT satellite images. Applying the voluntary carbon standard (VCS) methodology and the calibration period 1984–2014 (30 years), forest cover changes were predicted. The results showed that under the business-as-usual scenario, 155,698 ha of Central Hyrcanian forests will be declined by 2044. In general, the REDD+ Programme project implementation will prevent the release of 1,209,231 tCO2e. Based on the social cost of carbon (SCC) approach, the REDD+ Programme project implementation can save 12,092,310 US$. In addition, this approach can be used for the project design document (PDD) of the forest development mechanism

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Publisher Copyright: © 2021, The Author(s).Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.Peer reviewe

Effect of forest canopy gap on soil enzyme activity, dissolved organic matter and organic acids

Canopy gaps play an important role in the dynamics of temperate forests. The present study aimed to evaluate the effect of canopy gaps area on soil biochemical activities in Khanikan region of Nowshahr. In this study, 32 canopy gaps with small (195-205 m2), medium (397-406 m2), large (593-604 m2) and very large (792-807 m2) areas, 8 replications for each, were considered. Five points were selected within each canopy gap; soil samples were taken and mixed due to transferring to laboratory for analysis of physico-chemical, biological and biochemical properties. According to findings, whole of soil physico-chemical (except for silt content) and biological properties were significantly affected by different canopy gaps areas. The highest urease activity was found under medium and small (22.97 and 22.54 µg NH4+–N g−1 2 h−1) canopy gap areas, respectively. Medium gaps showed the most values of acid phosphatase (633.75 µg PNP g−1 h−1), arylsulfatase (153.38 µg PNP g−1 h−1) and invertase (273.25 µg Glucose g−1 3 h−1). Greater amounts of dissolved organic carbon (94.73 mg/kg) and dissolved organic nitrogen (34.66 mg/kg) were found under very large and medium canopy gap areas, respectively. Creation of very large canopy gaps was due to increasing of fulvic (454.62 mg/100g) and humic (888.88 mg/100g) acids in the studied forest ecosystem. As a general conclusion, based on forest sustainable management, it is proposed to avoiding of large and very large canopy gaps creation

Effect of Caucasian alder (Alnus subcordata C. A. Mey.), Chestnut-leaved oak (Quercus castaneifolia C. A. Mey.) and horizontal cypress (Cupressus sempervirens L. var. horizontalis (Mill.) Gord.) plantation on litter, soil and CO2 emission characters

Different plant covers have various effects on ecosystem litter and soil characters. This research aims to study the effect of different forest covers (Alnus subcordata C. A. Mey., Quercus castaneifolia C. A. Mey. and Cupressus sempervirens L. var. horizontalis (Mill.) Gord.) on litter, soil and CO2 emission characters in the forest management plan of Nowshahr Neirang-Khanikan. Soil samples were taken from the organic (litter) and mineral (0-15cm) layers using randomly systematic method. Litter quality characters (carbon and nitrogen), soil bulk density, texture, water content, pH, organic carbon, total nitrogen and CO2 emission (in different water content and temperature regimes) were measured in the laboratory. Results showed that the highest values of litter nitrogen, silt, pH were found in alder plantation, whereas greater amounts of C/N of litter, water content, organic carbon, C/N of soil and CO2 emission were found under cypress stand. The highest amount of sand was detected under oak stand. The maximum of CO2 emission were occurred in field capacity moisture regime and higher temperature in whole of studied plantations. The results of this research indicate that afforestation with needle-leaved species, Cupressus sempervirens var. horizontalis, can be effective on the increasing CO2 emission from soil that must be considered in ecosystem management from the global warming point of view

Earthworm population and microbial activity temporal dynamics in a Caspian Hyrcanian mixed forest

Few studies have analyzed how tree species within a mixed natural forest affect the dynamics of soil chemical properties and soil biological activity. This study examines seasonal changes in earthworm populations and microbial respiration under several forest species (Carpinus betulus, Ulmus minor, Pterocarya fraxinifolia, Alnus glutinosa, Populus caspica and Quercus castaneifolia) in a temperate mixed forest situated in northern Iran. Soil samplings were taken under six individual tree species (n = 5) in April, June, August and October (a total of 30 trees each month) to examine seasonal variability in soil chemical properties and soil biological activity. Earthworm density/biomass varied seasonally but not significantly between tree species. Maximum values were found in spring (10.04 m−2/16.06 mg m−2) and autumn (9.7 m−2/16.98 mg m−2) and minimum in the summer (0.43 m−2/1.26 mg m−2). Soil microbial respiration did not differ between tree species and showed similar temporal trends in all soils under different tree species. In contrast to earthworm activity, maximum microbial activity was measured in summer (0.44 mg CO2–C g soil−1 day−1) and minimum in winter (0.24 mg CO2–C g soil−1 day−1). This study shows that although tree species affected soil chemical properties (pH, organic C, total N content of mineral soils), earthworm density/biomass and microbial respiration are not affected by tree species but are controlled by tree activity and climate with strong seasonal dynamics in this temperate forest.This work was done by financial support of Tarbiat Modares University, Tehran, Iran.Peer Reviewe

Classification of humus forms in Caspian Hyrcanian mixed forests ecoregion (Iran): Comparison between two classification methods

Temperate forest productivity and functioning may be explained by complex interactions among tree canopy composition, topographic conditions, climate, morphogenetic identification and classification of humus forms. In this study, we report the main morphological feature of humus profiles classified according to both American (AHCM) and European (EHCM) classifications under the six most common forest stands in northern Iran, i.e., Alnus subcordata (AS), Acer velutinum (AV), Fagus orientalis-Carpinus betulus (FO-CB), Carpinus betulus (CB), Fagus orientalis (FO), and Fagus orientalis-Carpinus betulus-Parrotia persica (FO-CB-PP). Organic and organic-mineral layers samples were collected in 61 permanent plots (20\u202f 7\u202f20\u202fm) within a 30\u202f 7\u202f30\u202fcm metal frame, for identification. Our result showed that Mull was the dominant humus system according to both classifications, whereas Mor (AHCM) and Amphi (EHCM) were the less frequent humus systems in the study area. Mull and Amphi (EHCM) were dominant at the lowest slope and altitude under AS canopy cover; Moder was usually present at intermediate slope and altitude under FO-CB and FO-CB-PP; while Mor was the dominant form at intermediate slopes and highest altitudes under FO and FO-CB. Due to the temperature changes and litter decomposition, altitude seems to be the best predictor of humus type and litter thickness. Our findings also indicate that EHCM could be preferred in the identification and classification of humus forms in temperate deciduous forests in Iran

Impact of forest degradation and reforestation with Alnus and Quercus species on soil quality and function in northern Iran

Forest degradation causes soil carbon losses and affects soil C and N cycling. However, it is not clear how reforestation of degraded areas with different species affects soil and ecosystem restoration, particularly in northern Iran. The aim of this study was to evaluate the effect of forest degradation and reforestation with two contrasting species: Alnus and Quercus as N-fixing and non N-fixing tree species, respectively, on soil quality and function after 30 years in the northern Iran region. We selected four forest stands: Carpinus betulus-Parrotia persica natural forest (NF), Alnus subcordata (AP) and Quercus castaneifolia (QP) plantations as rehabilitated areas, and a degraded natural forest (DNF). We examined the main litter and soil chemical properties and soil C and N microbial fractions. Litter and soil physico-chemical properties and microbial activity differed among land covers. As expected, deforestation caused a decrease in most soil C and N fractions as well as in soil microbial activity with an increase in metabolic quotient-qCO. The plantation with Quercus spp. improved substrate induced respiration, as well as microbial biomass carbon and dissolved organic carbon compared to the Alnus plantation, whereas mineral N was similar in the natural site and the Alnus plantation. Although forest plantations had not reached the same values of microbial activity as the natural forest soils, soil C and N fractions were similar to the natural site after 30 years. The findings of this study support the importance of preserving natural forests for soil conservation. In addition, employing of N fixing trees such as Alnus spp. or, Quercus spp., suitable native broadleaved species, is proposed for the rehabilitation of degraded natural forests. Although both forest plantations led to soil recovery after 30 years, Quercus plantations were more efficient in restoring microbial communities than Alnus plantations indicating that litter quantity is more important than litter quality for soil recovery

Reaction and fractal description of soil bio-indicator to human disturbance in lowland forests of Iran

Mollaei-Darabi S, Kooch Y, Hosseini SM. 2014. Reaction and fractal description of soil bio-indicator to human disturbance in lowland forests of Iran. Biodiversitas 15: 58-64. Earthworms are expected to be good bio-indicators for forest site quality. The deforestation of land into another function could changes the soil features that could effect on earthworm population. This study was conducted to understand the changes of soil functions, resulting from exploitive management using some soil features and their fractal dimensions. Two sites were selected, consisting of an undisturbed forest site (FS) and a completely deforested site (DS) in lowland part of Khanikan forests located in Mazandaran province, north of Iran. Within each site 50 soil samples were obtained from 0-30cm depth along two sampling lines with 250 meter length for each. Deforestation brought a lower soil quality in the sites under the study. Decreasing silt, clay, moisture, pH, carbon to nitrogen ratio, available Ca, earthworm density and biomass, increasing bulk density and sand were few outcomes of the deforestation. Except for clay, the deforestation affect on fractal dimension of soil features. The fractal dimension of bulk density, silt, moisture, pH, earthworm density and biomass were decreased imposed by deforestation. Our results suggest that deforestation should be regarded as an effective factor on variability of soil features that are tied to forest ecology. This is significant for evaluating forest management policies and practices with respect to effects on soil and also for the use of soils as indicators, especially earthworms as bio-indicator, of forest ecosystems