川西亚高山/高山森林土壤氧化还原酶活性及其对季节性冻融的响应

川西亚高山/高山森林土壤通常具有明显的季节性冻融特征。为深入了解川西亚高山/高山森林冬季土壤生态过程,于2008年11月-2009年10月,在土壤初冻期、冻结期和融化期及生长季节,研究了不同海拔(3582 m、3292 m和3023 m)岷江冷杉林的土壤氧化还原酶活性及其对土壤冻融的响应。土壤冻结时间和冻融循环次数随海拔的增加而增加。冻融格局显著影响了土壤氧化还原酶活性,但不同土壤酶在不同海拔表现出明显差异。土壤过氧化物酶和脱氢酶活性受初冻期冻融循环和温度降低影响显著下降,而过氧化氢酶活性明显上升。3种土壤氧化还原酶活性在土壤温度相对稳定的冻结期变化不显著,但在融化期随着土壤温度急剧增加经历一个明显的活性高峰后快速降低,且冻结时间最长和冻融循环次数最多的3582 m变化更为显著。此外,海拔和土层的交互作用显著影响了过氧化物物活性,但对脱氢酶和过氧化氢酶活性不显著。脱氢酶活性与土壤温度极显著相关,但过氧化物酶和过氧化氢酶活性与土壤温度的相关性随海拔差异而不同。这些结果表明川西亚高山/高山森林冬季土壤氧化还原酶仍然具有较高的活性,但受到季节性冻融及其变化的显著影响。     

Seasonal dynamics of soil fauna in the subalpine and alpine forests of west Sichuan at different altitudes

The climate (especially temperature) often plays an important role in the structure, function as well as composition of soil organisms in different latitudes and altitudes. As one of the essential components of soil ecosystem, soil faunal community not only lays their roles as soil engineer in material cycling and energy flow, but also acts as the sensitive bio-indicator to environmental change. However, little information has been available on the responses of soil faunal community to the changed environment at different altitudes and seasons. In order to understand the seasonal dynamics of soil faunal diversity under different forests with varying altitudes, three fir (Abies faxoniana) forests were selected covering a 600 m vertical transition zone. The primary fir forest at 3600 m (A1) of altitude, mixed fir and birch forest at 3300 m (A2) of altitude, and secondary fir forest at 3000 m (A3) of altitude are representative forests in the subalpine and alpine region of west Sichuan. A 2 years study was conducted in the three subalpine and alpine forests from May in 2009 until October in 2010. Soil samples were collected in both the soil organic layer and mineral soil layer. Soil macro-fauna were picked up by hand in the fields. Meso/micro-fauna and damp living fauna were separated and collected from the soil samples by Baermann and Tullgren methods in laboratory, respectively. A total of 74,827 individuals were collected in the 2 years, belonging to seven phyla, 16 classes, 31 orders and 125 families by preliminary identification. Similar dominant groups were detected in different forests at different altitudes, consisting of Spirostreptida, Formicidae, Staphylinidae, Hesperinidae, Onychiuridae, Isotomidae, Oribatuloidae, Alicoragiidae, Secernentea, and Adenophorea. In contrast, the ordinary species of macro-fauna and the ratios of Acarina to Collembolan were obviously different. For instance, the ordinary species were dominated by Cydmaenidae and Mycetophilidae at the A1, Scaphidiidae and Helicinidae at the A2, and Lumbricida and Agelenidae at the A3, respectively. Both the individual density and the number of soil faunal groups were significantly higher in soil organic layer than those in mineral soil layer. The density and group of macro-, meso- and micro-fauna in different forests showed the order as A2 > A1 > A3, but the density of damp living fauna showed the order as A1 > A2 > A3. The functional groups of macro-fauna were mainly dominated by saprozoic. The highest density and group of macro-fauna was observed in August, while the highest value of meso/micro-fauna was detected in October. In addition, the Jacard similarity indices showed that the composition and structure of soil fauna were similar in the different forests varied with altitudes, but the Shannon–Wiener indices were significantly different. The highest values of Shannon–Wiener indices were observed in October at both the A1 and A3, and in August at the A2. The results suggested that soil faunal community kept a high diversity in the subalpine and alpine forests of west Sichuan, and their structures were significantly affected by the variation of altitudes, which provided important scientific evidences for understanding the ecological processes in the subalpine and alpine coniferous forests.     

Germination et croissance des plantules de hêtre (Fagus sylvatica) sous contraintes climatiques et allélopathiques

Recruitment is a key process for forest sustainability, especially in warm margin of distribution area. The influence of climate (temperate or warm), of soil water availability, and of allelopathic interactions from different forest species have been tested on the germination of Fagus sylvatica in controlled climatic conditions. Germination rates of non-dormant Fagus seeds were improved by relatively warm temperatures (20 °C), but reversibly stopped under heat constraint (27 °C). The relative growth rate of Fagus seedlings was better under temperate climatic conditions. Foliar extracts of Hedera helix showed the highest allelopathic effect on Fagus recruitment, especially in temperate conditions. Our results suggest a limitation of Fagus recruitment in warm margin of its distribution area, and a modulation of recruitment success according to the identity of plant neighbourhood.     

Effect of seasonal freeze–thaw cycle on net nitrogen mineralization of soil organic layer in the subalpine/alpine forests of western Sichuan,China

Nitrogen mineralization, a main way that soil organic nitrogen converts to mineral nitrogen, is one of the key processes in soil nitrogen cycle. The mineral nitrogen has an important role in plant growth in the growing season. It has been widely accepted that soil freezing in winter can kill a number of microorganisms, weakening soil nitrogen mineralization. However, more and more recent studies have documented that soil microorganisms still have high activity during the deep freezing period, and obvious nitrogen mineralization in winter. Seasonal freeze–thaw cycle is a common phenomenon in the subalpine/alpine forest region, which may have a strong effect on soil ecological processes. Furthermore, the changing pattern of seasonal freeze–thaw cycles might have a significant influence on soil nitrogen mineralization in this region in the scenarios of global warming. As yet, little attention has been given to nitrogen mineralization of soil organic layer as affected by changed seasonal freeze–thaw pattern, although the increasing studies have demonstrated that winter warming might give strong effects on the litter decomposition and microbial activity in the subalpine/alpine forest regions. Therefore, a method of intact soil core incubation in combination with natural environmental gradient was employed by transferring forest soils from 3582 m (A₁) of altitude to 3298 m (A₂) of altitude and 3023 m (A₃) of altitude in the subalpine/alpine forests of western Sichuan, respectively. The amounts and rates of net nitrogen mineralization in soil organic layer were measured. The incubation period included the growing season and the freeze–thaw season from May 24, 2010 to April 19, 2011. The results suggested that significant net nitrogen mineralization was only observed in soil organic layer at low altitude (A₃) during the whole incubation period. Forest soils at higher altitudes (A₁ and A₂) showed obvious soil nitrogen immobilization. In comparison with the growing season which showed remarkable nitrogen immobilization characteristic, the freeze–thaw season showed obvious nitrogen mineralization at lower altitudes (A₂ and A₃). In contrast, the nitrogen immobilization amounts at high altitude (A₁) in freeze–thaw period were less than those in the growing season. Besides, the maximum of net nitrogen mineralization amounts and rates at high altitude (A₁) in soil organic layer mainly occurred in the late stage of growing season and the onset of freezing, soil nitrogen mineralization at the middle altitude (A₂) mainly occurred in the onset of freezing and the deep freezing period, while the highest amount and rate of net nitrogen mineralization at low altitude (A₃) occurred in the early stage of thawing and the late stage of growing season. Furthermore, the amount and rate of soil net nitrogen mineralization during the freeze–thaw season were increasing with the decrease of altitude, which correlated with soil freeze–thaw cycle and freezing process at different altitudes. These results indicated that increasing soil temperature in the future could not only significantly enhance soil nitrogen mineralization in the freeze–thaw season, but also improve soil nitrogen mineralization by increasing freeze–thaw cycle times and shortening freeze–thaw period. However, the processes were significantly influenced by soil micro-environment of subalpine/alpine forest regions.     

Environmental indicators for estimating the potential soil respiration rate in alpine zone

Soil respiration is the main form of carbon flux from soil to atmosphere in the global carbon cycle. The effect of temperature on soil respiration rate is important in evaluating the potential feedback of soil organic carbon to global warming. We incubated soils from the alpine meadow zone and upper rocky zone along an altitudinal gradient (4400–5500 m a.s.l.) on the Tibetan Plateau under various temperature and soil moisture conditions. We evaluated the potential effects of temperature and soil moisture on soil respiration and its variation across altitudes. Soil respiration rates increased as the temperature increased. At 60% of soil water content, they averaged 0.21–5.33 μmol g soil⁻¹ day⁻¹ in the alpine meadow zone and 0.11–0.50 μmol g soil⁻¹ day⁻¹ in the rocky zone over the experimental temperature range. Soil respiration rates in the rocky zone did not increase between 25 and 35 °C, probably because of heat stress. Rates of decomposition of organic matter were high in the rocky zone, where the CN ratio was smaller than in the middle altitudes. Soil respiration rates also increased with increasing soil water content from 10% to 80% at 15 °C, averaging 0.04–2.00 μmol g soil⁻¹ day⁻¹ in the alpine meadow zone and 0.03–0.35 μmol g soil⁻¹ day⁻¹ in the rocky zone. Maximum respiration rates were obtained in the middle part of the alpine slope in any case of experimental temperature and soil moisture. The change patterns in soil respiration rate along altitude showed similar change pattern in soil carbon content. Although the altitude is a variable including various environmental factors, it might be used as a surrogate parameter of soil carbon content in alpine zone. Results suggest that temperature, soil moisture and altitude are used as appropriate environmental indicators for estimating the spatial distribution of potential soil respiration in alpine zone.     

亚高山/高山森林土壤有机层氨氧化细菌和氨氧化古菌丰度特征

为了解季节性冻融作用对川西亚高山/高山地区土壤氨氧化微生物群落的影响,采用qPCR技术,以氨单加氧酶基因的α亚基(amoA)为标记,在生长阶段、冻结阶段、融化阶段中的9个关键时期调查了该地区不同森林群落：岷江冷杉(Abies faxoniana)原始林(PF)、岷江冷杉(A. faxoniana)和红桦(Betula albosinensis)混交林(MF)、岷江冷杉次生林(SF)土壤有机层的氨氧化细菌(ammonia-oxidizing bacteria, AOB)和氨氧化古菌(ammonia-oxidizing archaea, AOA)丰度的特征。结果表明,三个森林群落土壤有机层中都具有相当数量的氨氧化细菌和古菌,均表现出从生长阶段至冻结阶段显著降低,在冻结阶段最低,但冻结阶段后显著增加,在融化阶段为全年最高的趋势。土壤氨氧化微生物类群结构(AOA/AOB)受负积温影响明显。冻结后期三个森林群落土壤负积温最大时,AOA数量明显高于AOB,但其他关键时期土壤氨氧化微生物类群结构与群落类型密切相关。高海拔的PF群落土壤有机层表现为AOA>AOB(冻结初期除外),低海拔的SF群落中表现为AOB>AOA(冻结后期除外),而MF群落则仅在融冻期和生长季节末期表现为AOB>AOA。这些结果为认识亚高山/高山森林及其相似区域的生态过程提供了一定的科学依据。     

利用海拔差异模拟增温对高山森林土壤溶解性有机碳和有机氮含量的影响

在2010年5月—2011年4月和2011年5月—2012年4月2个培养周期内,采用原状土柱野外控制试验,利用海拔梯度变化研究了温度增加对川西高山森林土壤溶解性有机碳(DOC)和有机氮(DON)动态的影响.结果表明: 经模拟增温处理(降低海拔)的土壤有机层和矿质土壤层DOC和DON含量在2个连续培养周期内的各关键时期均呈现明显的动态变化.海拔3300和3000 m样地比海拔3600 m 样地土层DOC含量分别增加6.8和26.6 mg·kg^-1.海拔3600、3300和3000 m样地土层DOC含量均在第1个培养周期的生长季末最高,分别为408.0、317.9和448.2 mg·kg^-1,在第2个培养周期的生长季节中期最低, 分别为33.1、32.4和36.5 mg·kg^-1.与海拔3600 m样地相比,海拔3300和3000 m样地土层DON含量分别增加2.3和30.4 mg·kg^-1.除海拔3000 m样地以外,海拔3600和3300 m样地土层DON含量在第1个培养周期内的生长季节中期最高,分别为65.9和64.6 mg·kg^-1,在第1个培养周期内的融化期最低,分别为31.9和37.1 mg·kg^-1.模拟增温处理增加了样地内土壤有机层DOC和DON含量,降低了矿质土壤层DOC含量、土壤有机层及矿质土壤层DOC/DON值.土壤有机层DOC/DON值与DOC含量呈显著正相关,与DON含量呈显著负相关;矿质土壤层DOC/DON值与DOC含量呈显著负相关,与DON含量呈显著正相关.未来全球气候变暖可能通过影响高寒森林土壤温度和冻融循环格局,增加整个土层DOC和DON含量,进而影响高寒森林土壤碳、氮循环过程.     

Effects of varying temperature on the reproduction and damage potential of Heterodera schachtii to Chinese cabbage (Brassica rapa pekinensis)

Heterodera schachtii is a well-known, destructive pathogen of Chinese cabbage (Brassica rapa pekinensis) in Korea, and several studies have attempted to find a potential control measure against it. This study is the first to investigate the effects of varying temperature on the reproduction and damage potential of H. schachtii to Chinese cabbage. Chinese cabbage plants were inoculated with H. schachtii at different densities (1, 2, or 4 juveniles per gram of soil) and grown under three temperature regimes: constant (15, 20, or 25 °C), increasing (10, 14, and 18 °C), and fluctuating (positive, 16.7–22.0 °C; negative, 21.5–11.5 °C). At a constant temperature after 30 days of inoculation, both Chinese cabbage and H. schachtii performed best at 20 °C. However, after 60 days of inoculation, H. schachtii had a significantly higher population at 20 °C, whereas cabbage growth was best at 25 °C. With increasing temperature, the numbers of cysts and females did not change significantly, and reached maxima at an initial temperature of 14 °C. However, the number of leaves and weights of the Chinese cabbage plants significantly differed at 14 °C. Under fluctuating temperatures, temperature decreases reduced the H. schachtii population.     

Vegetation mapping above tree line in Nandiar valley,western Himalayas. A multivariate approach

This paper communicates an analytical exploration of the vegetation above tree line in Nandiar valley western Himalayas with respect to climatic, edaphic and topographic factors. The alpine pasture stretches above the tree limits between elevations of 2850–3800 m. Thirteen stands were selected on the basis of physiognomy of vegetation in 2014–15. The leading life form and leaf spectra were therophytes and microphyll respectively. Four plant communities were identified through two ways indicator species analysis at cut level 2. Bray-Curtis ordination showed that maximum stands have common species. Detrended correspondence analysis grouped species having similar habitats in ordination space. Canonical correspondence analysis constrained species along different environmental variables. The significant result were contribution by phosphorous (P = 0.01) and wind speed (P = 0.08). Few plant species like Betula utilis and Podophyllum emodi are threatened due to its medicinal collection. The alpine pasture of Nandiar valley is under severe stress due to anthropogenic and grazing factors. Overall, this research article call for greater attention to the types of conservation actives occurring and the ways they are working together to protect and recover the global alpine biodiversity.     

Distribution characteristics and factors influencing the ecosystem in western Hubei

Western Hubei is the most concentrated area of forest resources in Hubei Province, and the knowledge of the distribution characteristics of ecosystem carbon density is important to understand the regional characteristics of carbon density and its mechanism of formation. Carbon density and factors influencing different layers in the ecosystem were studied by using field data. The average carbon density of ecosystems in western Hubei was 159.05 t/hm²; the carbon density of different forest types in descending order was Abies fargesii forests (362.25 t/hm²), mixed broadleaf-conifer forests (154.13 t/hm²), broad-leaved forests (146.09 t/hm²), and coniferous forests (135.76 t/hm²), and ecosystem carbon density increased with increasing age. The carbon density of the arborous layer, shrub layer, and soil layer of A. fargesii forests was significant higher than that of the other forests (P < 0.05), indicating the carbon storage per unit area of A. fargesii forests, which grow at higher elevations, was the greatest. The carbon density in arborous layers of broad-leaved forests, mixed broadleaf-conifer forests, and coniferous forests was 39.29 t/hm², 48.99 t/hm², and 48.39 t/hm², respectively. Those of the soil layer were 102.96 t/hm², 100.97 t/hm², and 82.37 t/hm², respectively, and there were no significant differences among them. Among the three forest types, carbon density in the litter layer was greater than that of the shrub layer, which indicated the litter layer plays an important role in carbon storage. The carbon density of mixed broadleaf-conifer forests was greatest, excluding A. fargesii forests, in medium (58.71 t/hm²) and mature forests (79.66 t/hm²). Thus, the carbon sink of mixed broadleaf-conifer forests had more potential than the others at the medium and mature forest stage. The soil layer carbon density in different forests constituted 60.67—70.48% of the entire ecosystem, and was 1.70—2.62 times greater than that of the arborous layer. There are many factors influencing ecosystem carbon density, which result from the interaction of environmental and topographical factors. The main explanatory variables of carbon density of the region were altitude, precipitation, and canopy density. The vegetation and soil layer carbon density increased as altitude increased, and the rate of change for every vertical 100 m was 1.3 t/hm² and 1.9 t/hm², respectively (P < 0.05). Although the annual average precipitation only affected the carbon density of the vegetation, it increased to 4 t/hm² (P < 0.01) when average precipitation was >100 mm.     

Promoting effect of Fusarium oxysporum [f.sp. strigae] on abundance of nitrifying prokaryotes in a maize rhizosphere across soil types

The integrated application of resistant crop varieties with biological control agents (BCAs) such as the Fusarium oxysporum [f.sp. strigae] strain “Foxy-2” has shown to be effective in fighting off the weed Striga hermonthica which is parasitic to several cereals cultivated in Sub-Saharan Africa (Schaub et al., 2006; Venne et al., 2009). “Foxy-2” proliferates in the rhizosphere and has been mainly studied for its virulence and mode of action. Contrary, no understanding is available regarding its interactions with key rhizosphere microorganisms steering relevant nutrient cycles in soils including nitrogen (N). In this study, we tested the hypothesis that “Foxy-2” displaces indigenous prokaryotic, N cycling communities in the maize rhizosphere due to competition for organic resources. Consequently, we evaluated if the application of an N-rich organic residue (i.e., Tithonia diversifolia with C/N ratio = 13, lignin content = 8.9%, polyphenol content = 1.7%) compensates these presumed competition effects. In a rhizobox experiment, quantitative polymerase chain reaction was used to follow the response of rhizosphere ammonia-oxidizing archaea (AOA) and bacteria (AOB) as well as total bacteria and archaea following “Foxy-2” inoculation in two physico-chemically contrasting soils (sandy Ferric Alisol versus clayey Humic Nitisol). Soils were treated with or without “Foxy-2”, S. hermonthica seeds, and T. diversifolia residues. Contrary to our expectations, we observed a distinct soil texture dependent, promoting effect of “Foxy-2” on rhizosphere prokaryotes. Abundance of AOA and total prokaryotic communities increased in response to “Foxy-2” in the sandy soil, while AOB remained unaffected. This effect on AOA was accelerated when T. diversifolia residues were incorporated. Further, in the clayey soil, AOA abundance was promoted when exposed to S. hermonthica infestation of maize. This suggested their capability to adapt to this biotic stress situation. It was concluded that “Foxy-2” did not pose a negative effect on targeted indigenous microorganisms, but the underlying mechanisms for the observed promoting effect of AOA abundance by “Foxy-2” inoculation are yet to be understood.     

辉腾锡勒草原干涸湖泊中氨氧化微生物群落结构分析

【目的】以内蒙古辉腾锡勒草原九十九泉湿地为对象,研究湖泊干涸过程中氨氧化微生物的群落结构及其变化。【方法】通过MPN-PCR定量测定氨氧化古菌(AOA)和氨氧化细菌(AOB)的数量;构建amoA基因克隆文库,进行系统发育分析;结合土壤环境因子,探讨湿地退化过程中影响氨氧化微生物的潜在因素。【结果】依湖泊湿地退水梯度的不同样点中,有75%的样点AOB的数量高于AOA,AOB与AOA的数量比率为0.3-18.1。从湖心到湖岸草原带,AOA和AOB的数量有明显增加,但生物多样性呈降低趋势,二者没有呈现正相关。研究发现,AOB的数量与土壤中NH 4+-N的变化存在良好响应。系统发育分析显示,退化湖泊湿地AOA克隆序列均来自于泉古菌门(Crenarchaeota);AOB的amoA基因的克隆序列大部分与亚硝化单胞菌属(Nitrosomonas)有一定同源性,较少部分与亚硝化螺菌属(Nitrosospira)有一定同源性。【结论】湖泊退水过程增加了湿地土壤氨氧化微生物的数量,而氨氧化微生物的种群丰度有所降低。AOA和AOB群落对湖泊湿地的退化过程做出了响应,其中AOB的响应较为明显,氧化条件和土壤铵浓度的改变可能是促成这种响应的重要原因。     

Effects of plateau pika (Ochotona curzoniae) on alpine meadow phytocoenosium and analysis of the strategy it uses to expand habitat

High-density plateau pikas (Ochotona curzoniae) disturbance is one of the main causes of alpine meadow degradation. The response of phytocoenosium to the disturbance of plateau pika may reflect its habitat expanding strategy. We used quadrat sampling method to investigate vegetation height, coverage, and aboveground biomass of non-pika area (NA), transition area (TA), and pika-active area (AA) distributed continuously in alpine meadow located in Guoluo Tibetan Autonomous County of Qinghai Province in 2011 and 2012. The results showed that, from NA to AA (i) vegetation coverage, height, and above-ground biomass decreased (P < 0.01). (ii) While the number of plant species decreased from 41 to 30, and species diversity decreased significantly (P < 0.05), evenness of the alpine meadow showed no significant variations. (iii) Dominant species changed from grasses to weeds. (iv) While plants in TA showed no obvious difference in height between 2011 and 2012, coverage reduced significantly (P < 0.05). These results demonstrate that (i) plateau pikas disturbance on alpine meadow will change plant community structure and composition, directly leading to degeneration of alpine meadow. Additionally, (ii) plateau pikas expand their habitat by altering plant coverage firstly.     

Ecological effects of forest roads on plant species diversity in Caspian forests of Iran

Current research includes the effects of asphalt forest roads on changes of plant cover and tree regeneration from asphalt forest roads edges towards its inner parts in two compartments of Nave Asalem forests located in the north of Iran. For this reason, in each side of road, 6 sample plots (20 m × 20 m) were established for measuring plant species diversity. In each sample plot, ground vegetation and tree regeneration were assessed within nine 2 × 2 m micro plots. In total, 12 sample plots and 108 μ plots were established. Results indicated that the road positions were effective on plant species diversity. The highest diversity and evenness indices value were observed down of the road compared to the up of the road position for herbal and tree regeneration layers. The same results were found also for herbal richness indices. Up of road position had the greatest value of richness indices in comparison to the other road position for tree regeneration layer. Also, the results showed that diversity, richness, and evenness indices were decreased with the increasing of distance from the road side for herbs and tree regeneration layers. This study indicated that roads can increase plant biodiversity; that is, tree regeneration density.     

Continued optimization of the M5 NAM ML375: Discovery of VU6008667, an M5 NAM with high CNS penetration and a desired short half-life in rat for addiction studies

This letter describes the continued optimization of M₅ NAM ML375 (VU0483253). While a valuable in vivo tool compound, ML375 has an excessively long elimination half-life in rat (t_1/2 = 80 h), which can be problematic in certain rodent addiction paradigms (e.g., reinstatement). Thus, we required an M₅ NAM of comparable potency to ML375, but with a rat t_1/2 of less than 4 h. Steep SAR plagued this chemotype, and here we detail aniline replacements that offered some improvements over ML375, but failed to advance. Ultimately, incorporation of a single methyl group to the 9b-phenyl ring acted as a metabolic shunt, providing (S)-11 (VU6008667), an equipotent M₅ NAM, with high CNS penetration, excellent selectivity versus M_1–4 and the desired short half-life (t_1/2 = 2.3 h) in rat.     

Microwave-enhanced extraction of lignin from birch in formic acid: Structural characterization and antioxidant activity study

A rapid and mild extraction protocol for the preparation of lignin was achieved by microwave-assisted heating in formic acid at 101 °C under atmospheric pressure. In this case, birch lignin was extracted with microwave heating process (ML) in formic acid and characterized by elemental analysis, FTIR, GPC, ¹H NMR and ¹³C–¹H HSQC. In addition, the antioxidant activity of the samples was investigated. For comparative study, milled wood lignin (MWL) and lignin extracted with oil bath heating process (OL) were prepared. The results showed that the lignin yield under microwave heating was much higher than that under oil bath heating. A maximal delignification degree (89.77%) was achieved when microwave heating time was 30 min. When double time (60 min) was used under oil bath heating, the delignification degree was 66.11%. The structural characterization showed that the lignin structure of ML did not change dramatically, which is a mixture of GS-type with β-O-4′ ether bond as the major inter-unit linkage. As for antioxidant activity against DPPH, the radical scavenging index (RSI) of ML was 1.20, which was higher than that of MWL (0.53), suggesting that ML exhibited much higher antioxidant activity than MWL.     

Soil properties along altitudinal gradient in Himalayan temperate forest of Garhwal region

The aim of the present study was to analyse the soil properties in different seasons at varying altitudes. The study was carried out in Dhanaulti forest, falls under temperate region of Garhwal Himalaya in Uttarakhand State, India. Physical properties and chemical properties of the soil were estimated using all standard procedures. In the present study, sand particles were reported highest (77.21%) in rainy season followed by in summer (70.17%) and winter (63.15%) seasons. The silt and clay particles also followed similar trend as sand which reduced in order of rainy > summer > winter seasons. The water holding capacity of soil ranged from 62.13 to 67.70%. The majority of soils were dark brown to dark yellowish brown in colour, which is considered having higher potential of water holding capacity. The values of nitrogen ranged between 0.01 to 0.012% (upper altitude), 0.009 to 0.011% (middle altitude) and 0.007 to 0.011% (lower altitude). The effects of altitudes and seasons in nitrogen show significant variation. Potassium ranged between 102.29 and 206.22 kg ha^? 1. The combined effect of season and soil-depth also showed significant variation in level of potassium. The soil organic carbon values were between 0.14 and 0.19% and pH values ranged between 6.33 and 6.75 which was slightly acidic in nature.     

The assessment of anti-tumoral activity of polysaccharide extracted from terrestrial filamentous fungus

Fungal polysaccharides are well-known for the medicinal properties such as antitumor and immunomodulating effects. Hence, this study evaluated antitumor effects of polysaccharide extracted from Fusarium sp. isolated from soil samples of Karaj district, Alborz, Iran along with its taxonomic study. The filamentous fungus strain FK1 was isolated from the soil sample of Karaj, Iran. The strain was identified based on cultural, morphological and 18 S rRNA gene parameters as Fusarium. Further, the strain Fusarium was cultured in fermented broth of modified (PDB) for 10  days at 25 °C. The polysaccharide of strain FK1 was extracted from the mycelium free supernatant by boiling water method and evaluated for antitoxicity effect on two human cancer cell lines: HeLa cell line and Lymphoblastoid cell line (LCL) by MTT method. Findings revealed that water-extracted from mycelia polysaccharide of strain FK1 had the highest cytotoxicity effect against LCL which is the cause of B lymphocyte cancer, at 50  μg/ml concentration dose (114 ± 1.63) followed by 100  μg/ml (105 ± 0.57) and 10  μg/ml (104 ± 0.57), while it did not have a considerable effect on HeLa cell line. Fusarium could be alternative sources as an antitumor component.     

Variation in soil properties under different land uses and attitudinal gradients in soils of the Indian Himalayas

We studied the interaction effects of 8-different land uses systems viz., forestry (T₁), silvopastoral (T₂), horticulture (T₃), agrihorticulture (T₄), agrisilviculture (T₅), agrihortisilviculture (T₆) > grassland (T₇) and agriculture (T₈) in 2-altitudinal gradient for three consecutive soil layers of up to 1 m deep from sub-montane to low hill sub-tropical zone of Western Himalayas in Himachal Pradesh State of India. All the land uses under agroforestry practices viz., agrisilviculture, silvopastoral, agrihorticulture and agrihortisilviculture showed significantly enhanced values of pH, organic carbon (OC %), available N, P, K and exchangeable Ca, Mg and available S than agriculture land use. A maximum value of soil carbon (1.08%) was observed in forest land use followed by silvopastoral, horticulture, agrihorticulture, agrisilviculture, agrihortisilviculture, grassland and agriculture, respectively. Overall highest values of available N, P and K were observed under forest land use and silvopastoral among agroforestry systems. Available N, P, and K declined with increasing altitude. Exchangeable Mg followed the trend T₇ > T₂ > T₅ > T₁ > T₆ > T₃ > T₄ > T₈ and available Sulphur as T₇ > T₃ > T₂ > T₆ > T₅ > T₄ > T₈ > T_1, respectively. The value of exchangeable Ca and available S increased with increasing altitude. From the study it can be concluded that tree based land use systems of subtropical zone of the Himalayan region are more sustainable and environment friendly than agriculture and grassland use systems. Hence, they need to be conserved and promoted on large scale. The outcome of this paper will be helpful in convincing the farmers for adoptions of agroforestry practices in large scale.