Application of composted urban residue enhanced the performance of afforested shrub species in a degraded semiarid land

Improvement of physical-chemical soil quality is a key step for carrying out revegetation programs of degraded lands in Mediterranean semiarid areas. Organic residue addition may restore the quality of these areas. A field experiment was conducted in a silt-loam soil (Typic Petrocalcid) from a degraded semiarid Mediterranean area to evaluate the effect of the addition of a composted urban residue on soil aggregate stability, bulk density and chemical properties and on the establishment of Pistacia lentiscus and Retama sphaerocarpa seedlings. The composted residue was applied at a rate of 6.7 kg m(-2) before planting. The nutrient content (NPK), total organic C and water soluble C were increased and bulk density was decreased, in the rhizosphere soil of both shrub species, by the composted residue. The addition of composted residue significantly increased the soil aggregate stability by about 22% for both shrub species. The beneficial effect of the composted residue on soil quality still persisted 18 months after addition. Eighteen months after planting, the addition of composted residue to soil had increased significantly the production of shoot biomass by P. lentiscus and R. sphaerocarpa, by about 160% and 320% respectively, compared to control values. Composted residue addition to soil can be considered an effective preparation method of a degraded area for carrying out successful revegetation programs with Mediterranean shrubs under semiarid conditions.     

Temporal dynamics of arbuscular mycorrhizal fungi colonizing roots of representative shrub species in a semi-arid Mediterranean ecosystem

Arbuscular mycorrhizal (AM) symbiosis plays an important role in improving plant fitness and soil quality, particularly in fragile and stressed environments, as those in certain areas of Mediterranean ecosystems. AM fungal communities are usually affected by dynamic factors such as the plant community structure and composition, which in turn are imposed by seasonality. For this reason, a one-year-round time-course trial was performed by sampling the root system of two representative shrubland species (Rosmarinus officinalis and Thymus zygis) within a typical Mediterranean ecosystem from the Southeast of Spain. The 18S rDNA gene, of the AM fungal community in roots, was subjected to PCR-SSCP, sequencing, and phylogenetic analysis. Forty-three different AM fungal sequence types were found which clustered in 16 phylotypes: 14 belonged to the Glomeraceae and two to the Diversisporaceae. Surprisingly, only two of these phylotypes were related with sequences of morphologically defined species: Glomus intraradices and Glomus constrictum. Significant differences were detected for the relative abundance of some phylotypes while no effects were found for the calculated diversity indices. These results may help to design efficient mycorrhizal-based revegetation programs for this type of ecosystems.     

退化高寒草甸土壤微生物及酶活性特征

采用Biolog等方法,分析不同退化程度(未退化ND、轻度退化LD、中度退化MD、重度退化SD和黑土滩ED)高寒草甸0～10和10～20 cm土层土壤微生物量碳氮、碳代谢指纹和酶活性.结果表明: 所有草甸土壤微生物量、多样性指数和蔗糖酶活性在0～10 cm土层均显著高于10～20 cm土层,0～10 cm土层脲酶活性则显著低于10～20 cm土层.土壤微生物量C/N随草地退化程度加重显著降低.0～10 cm土层,ND和LD微生物量碳、氮均显著高于其他草地,MD、SD和ED微生物量碳无显著差异,MD微生物量氮显著低于其他草地;平均颜色变化率(AWCD)和McIntosh指数(U)随草地退化程度加重曲线下降,ND与MD间差异显著,其他草地间无显著差异;Shannon指数(H)和Simpson指数(D)在不同草地间均无显著差异;MD和SD脲酶活性最高,ED磷酸酶和蔗糖酶活性最低,与其他草地相比均差异显著.10～20 cm土层,ND和LD微生物量碳显著高于其他草地,MD、SD和ED间无显著差异,LD和ED微生物量氮显著高于其他草地,ND和SD间差异不显著;MD碳代谢指数最低,与LD和SD相比差异显著,ND和LD的AWCD和U指数均显著高于ED,H指数和D指数在ND、LD、SD和ED间差异不显著;ND和MD脲酶活性显著高于其他草地,LD、SD和ED间无显著差异;MD磷酸酶活性最高,与LD、SD和ED相比差异显著;MD蔗糖酶活性显著低于其他草地,ND、LD、SD和ED间差异不显著.不同退化程度高寒草地的地下生物量均与微生物量、碳代谢指数和磷酸酶呈显著正相关;脲酶与微生物量氮、H指数和D指数呈显著负相关.     

退化红壤区植被恢复过程中灌木层主要种群的生态位特征

选择闽西典型退化红壤地区,对6个不同恢复阶段的封育马尾松群落灌木层主要种群的生态位特征进行了分析,结果表明,多数种群的生态位宽度较窄,对资源的利用不充分,生态位宽度较大的种群顺序与其重要值大小顺序存在一致性,同时种群间生态位重叠较为普遍,对资源的利用方式相对一致。这些结果与退化红壤区植被恢复过程中生境条件的变化密切相关,有助于理解植被恢复动态规律,指导运用人工措施以加快恢复进程。     

三种木层孔菌子实体不同溶剂提取物抗氧化活性的研究

以抗坏血酸为阳性对照,分别对桑木层孔菌Phellinus mori、鲍姆木层孔菌Phellinus baumii和瓦宁木层孔菌Phellinus vaninii野生子实体甲醇提取物(ME)、氯仿提取物(CE)、乙酸乙酯提取物(EAE)、正丁醇提取物(BE)和热水提取物(WE)的体外清除DPPH(1,1-二苯基-2-三硝基苯肼)自由基、羟自由基和总抗氧化能力进行了检测。结果表明,3种木层孔菌的不同溶剂提取物都具有体外抗氧化活性。3种菌EAE清除DPPH自由基能力较强,其中瓦宁木层孔菌EAE清除DPPH自由基能力最强,IC50为10.65μg/mL。3种木层孔菌热水浸提物清除羟自由基的能力较强,鲍姆木层孔菌WE的清除率最高,1mg/mL时达到73.52%。另外,3种木层孔菌不同提取物总抗氧化能力和清除DPPH自由基能力基本相同,瓦宁木层孔菌BE的总抗氧化能力最强,1mg/mL时达到了167.7U/mL。3种木层孔菌相比,瓦宁木层孔菌不同提取物的体外抗氧化能力最强,其次是鲍姆木层孔菌,桑木层孔菌的体外抗氧化能力最弱。     

半干旱矿区3种灌木侧根分支处折力损伤后的自修复特性

以神东矿区用于植被恢复的小叶锦鸡儿、沙柳、沙棘为对象,研究侧根分支处极限抗折力学特性及受力受损后生长指标、力学特性的自修复能力,以明确半干旱采煤沉陷区灌木侧根分支处在遭受外力损伤后的可持续固土能力.结果表明: 3种灌木生长季初期侧根分支处极限抗折力和抗折强度均存在显著差异,种间变化均表现为小叶锦鸡儿>沙柳>沙棘.小叶锦鸡儿和沙柳侧根分支处抗折强度与纤维素、木质素及棕纤维素含量呈显著正相关,沙棘抗折强度与纤维素和木质素含量呈显著负相关,与棕纤维素含量呈显著正相关.沉陷区形成的折力损伤显著破坏灌木侧根分支处的正常生长和力学特性,即使通过3个月的自修复也不能恢复到未受损水平.生长指标自修复能力越强,抗折力自修复程度越高,修复率种间变化为沙棘(91.2%)>沙柳(82.0%)>小叶锦鸡儿(73.9%),抗折力修复率种间变化为沙棘(41.4%)>沙柳(37.1%)>小叶锦鸡儿(30.0%).3种灌木侧根分支处可持续固土指数分别为小叶锦鸡儿(2.2084)>沙柳(0.2009)>沙棘(-2.4093),说明在半干旱采煤沉陷区小叶锦鸡儿可持续固土能力最强,沙柳次之,沙棘最弱.     

不同优势树种菌根类型差异对土壤胞外酶活性的影响

土壤酶作为微生物代谢指标,在森林生态系统土壤碳和养分循环过程中发挥着重要作用,是土壤质量的重要指标。针对不同优势树种的内生菌根(AM)和外生菌根(ECM)所占比例差异,设置4种菌根类型比例梯度(即林分中ECM树种所占比例为<25%、25%—50%、50%—75%、>75%),分析4种林分中土壤水解酶[β-葡糖苷酶(BG)、β-N-乙酰氨基葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)、酸性磷酸酶(AP)]和过氧化物酶(PER)活性差异,运用方差分析和多重比较分析方法,探究水解酶和氧化酶沿菌根类型梯度的变化规律及原因。结果表明：(1)lnBG和ln(NAG+LAP)与lnAP的回归斜率小于1,且AP远大于BG和NAG+LAP,这表明森林土壤微生物受磷(P)限制更严重,随着林分中ECM优势树种的增加,微生物受碳(C)和P限制的状况得到缓解;(2)土壤有机碳(SOC)随着ECM树种占比的增加而增加,ECM森林比AM森林表现出更高的全氮(TN)和全磷(TP)含量;(3)随着林分中ECM树种占比的增加,BG、AP和NAG+LAP呈逐渐显著增加的趋势(P<0.05);但氧化酶活性...     

Variations of soil enzyme activities in a temperate forest soil

Soil enzyme activities (dehydrogenase, urease, phosphatase, and arylsulfatase) in a temperate forest soil were determined in relation to landscape position and seasons. Overstory of the area is dominated by Quercus mongolica, Kalopanax pictus, Carpicus cordata, and Acer pseudo-sieboldianum. The activities were measured in three patches, namely a north-facing backslope, a ridge, and a south-facing backslope in autumn and spring over 2 years. In addition, spatially more detailed analysis for phosphatase was conducted before and after litterfall production in six patches. Dehydrogenase, urease, phosphatase, and arylsulfatase activities varied 1.8–18.5 μg INT-formazan g⁻¹ h⁻¹, 45.4–347.0 μg NH₄ ⁺ g⁻¹ h⁻¹, 0.9–4.5 mmol pNP g⁻¹ h⁻¹, and 0.7–2.6 mmol pNP g⁻¹ h⁻¹, respectively. In general, higher enzyme activities were found in the northern aspect than in the southern aspect. This variation appears to be related to differences in chemical properties (e.g., Fe, Al, and Mg) of soil as well as distribution of leaf litter. Two patterns were discernible in relation to seasonal variations. Dehydrogenase and urease exhibited a positive correlation with mean air temperature, suggesting that temperature would be a major controlling variable for those enzymes. In contrast, higher activities were detected in autumn for phosphatase and arylsulfatase activities, which appeared to be closely related to litter production and distribution. Overall results of this study indicate that soil enzyme activities in a forest floor are influenced by several variables such as temperature, nutrient availability, and input of leaf litter, which are closely related to landscape position.     

Comparative community physiology: nonconvergence in water relations among three semi-arid shrub communities

Plant adaptations to the environment are limited, and therefore plants in similar environments may display similar functional and physiological traits, a pattern termed functional convergence. Evidence was examined for functional convergence among 28 evergreen woody shrubs from three plant communities of the semi-arid winter rainfall region of southern California. Both leaf and water relations traits were examined, including seasonal stomatal conductance (gs), specific leaf area (SLA), leaf specific conductivity (Kl), seasonal water potential (Psi w), stem cavitation resistance (Psi 50), and xylem density. Species display community-specific suites of xylem and leaf traits consistent with different patterns of water use among communities, with coastal sage scrub species utilizing shallow pulses of water, Mojave Desert scrub species relying on deeper water reserves, and chaparral species utilizing both shallow and deep moisture reserves. Communities displayed similar degrees of water stress, with a community-level minimum Psi w (Psi wmin) of c. -4.6 Mpa, similar to other arid communities. Pooled across sites, there was a strong correlation between Psi wmin and xylem density, suggesting that these traits are broadly related and predictive of one another. This comparative community physiology approach may be useful in testing hypotheses of functional convergence across structurally similar semi-arid communities.     

Revegetated shrub species recruit different soil fungal assemblages in a desert ecosystem

Plant and Soil - Revegetation with xeric shrubs is a widely applied measure for restoring degraded ecosystems in the deserts of northern China. However, knowledge on the soil fungal assemblages in...     

荒漠油蒿（Artemisia ordosica）根围AM真菌分布与土壤酶活性

于2007年10月在油蒿(Artemisia ordosica)集中分布区选取4个典型样地,分别从0～10cm、10～20cm、20～30cm、30～40cm和40～50cm土层采集根围土样,分离其丛枝菌根(arbuscular mycorrhiza,AM)真菌并测定了3种土壤酶活性.结果表明,在各样地0～50cm土层中油蒿根系AM真菌菌丝定殖率均很高,有典型的泡囊与丛枝结构.菌丝定殖率与泡囊定殖率呈显著正相关,但菌丝、泡囊和丛枝定殖率与AM真菌孢子密度和土壤酶活性之间都无相关性;孢子密度在不同样地及采样深度间差异明显,与土壤有机质、速效磷和速效氮含量都呈一定正相关关系.孢子密度与脲酶和酸性磷酸酶活性有显著或极显著相关关系,与碱性磷酸酶活性之间的相关性受到土壤pH的显著影响.孢子密度的峰值出现在0～10cm表层土,并随土壤剖面深度增加而降低.土壤酶活性在土壤垂直剖面显示与孢子密度同样的规律.不同样地间AM真菌分布及油蒿根系定殖率的差异表明,油蒿与AM真菌之间有良好共生性,对维护荒漠生态环境系统结构的完整性具有重要意义.     

Carbon isotope discrimination in three semi-arid woodland species along a monsoon gradient

Leaf carbonisotope discrimination () was measured for three dominant, semi-arid woodland species along a summer monsoon gradient inthe southwestern United States over a 2-year period. We tested the hypothesis that decreased humidity levels during the growing season along this gradient resulted in lower leaf values. Sites of similar elevation along the transect were selected and the range in monsoon contribution to overall annual precipitation varied from 18 to 58%, while total annual precipitation differed by a maximum of only 25% across this gradient. Leaf values in Quercus gambelii were negatively correlated with , a seasonally-weighted estimate of the evaporative humidity gradient, suggesting that stomatal conductance declined as transpiration potential increased. For two other trees that co-occurred along this gradient, Pinus edulis and Juniperus osteosperma, remained relatively constant despite large variation in . These woodland species represent the full spectrum of responses of carbon isotope discrimination to increases in evaporative potential; that of decline where c _i /c _a (ratio of internal to ambient CO₂ concentration) and presumably stomatal conductance decrease, and that of constancy where whole plant internal adjustments allow c _i /c _a to remain stable.     

Long‐term monitoring of shrub species translocation in degraded Neotropical mountain grassland

The introduction of plant species is a central topic in restoration ecology research. It is an effective technique to restore degraded ecosystems that present low resilience, such as the rupestrian grasslands. Once implemented, the transplantation of native species is monitored only in the short term, whereas long‐term monitoring should be preferred to identify potential changes in the restoration results. Our study is the first assessment of the transplantation success of 10 native shrub species in a degraded area of rupestrian grasslands, 8.5 years after transplantation. Survival, growth, and recruitment were assessed in 2004, 2008, and 2012. For all species, survival, growth, and recruitment varied over time. Although some species exhibited great mortality during the last 4 years, they also showed a great resprouting ability. Our results highlighted a trade‐off between survival and recruitment capacity. Most of the studied species showed remarkable ability to adapt to the extreme environment of the degraded area, persisting either through surviving or recruiting new individuals. We list nine native species, which are well appropriated for rupestrian grasslands restoration. In constrained environments, survival and resistance should represent criteria to select species for restoration project rather than fast growth and ground cover.     

Superoxide dismutase and total peroxidase activities in relation to drought recovery performance of mycorrhizal shrub seedlings grown in an amended semiarid soil

We studied the effect of inoculation with a mixture of three arbuscular mycorrhizal (AM) fungi (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) and Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) and addition of a composted organic residue on plant growth, nutrient uptake, mycorrhizal colonisation and superoxide dismutase (SOD, EC 1.15.1.1) and total peroxidase (POX, EC 1.11.1.7) activities in shoots of Juniperus oxycedrus seedlings after well-watered, drought and recovery periods. The mycorrhizal inoculation and composted residue addition significantly increased the growth, foliar nutrients (N, P, K) and shoot water content of the plants, independent of the water regime. POX activity in control plants increased during drought (about 250% higher than under well-watered conditions) and returned to initial levels after re-watering. The seedlings inoculated with AM fungi showed the highest values of POX activity, followed by the plants grown in the amended soil, which varied little during the drought and recovery periods. Drought decreased the SOD activity in shoots of both J. oxycedrus seedlings inoculated with AM fungi and those grown with composted residue, but did not affect that of control plants. After re-watering, the SOD activity in mycorrhizal or residue-amended plants increased, showing values similar to control plants.     

Neighborhood effects on soil properties,mycorrhizal attributes,tree growth,and nutrient status in afforested zones

A harmonious interspecies relationship is the key to the success of mixed afforestation. This study was conducted to assess the responses of afforestation species to their neighboring trees. We examined five types of stands—monocultures of Chinese pine (Pinus tabuliformis), black locust (Robinia pseudoacacia), sea‐buckthorn (Hippophae rhamnoides), and two mixtures (Chinese pine × black locust mixture and Chinese pine × sea‐buckthorn mixture)—in the Loess Plateau, northwestern China. The height and diameter at breast height of each tree species were measured, and rhizosphere soil, shoot, and root were sampled. In monocultures, black locust was taller than Chinese pine and sea‐buckthorn, while the height of Chinese pine and sea‐buckthorn was similar. In mixtures, Chinese pine grew better with sea‐buckthorn than alone as a result of modified soil properties and plant nutrition, but not with black locust. When Chinese pine was used as neighbors, it affected the level of arbuscular mycorrhizal (AM) colonization of black locust, soil properties and AM fungal spore density of black locust and sea‐buckthorn, but did not significantly affect their growth. Our results suggest that the reciprocal effects between tree species in mixture are not symmetric, and thus planning for efficient mixed afforestation requires knowledge of species‐specific growth rate, nutrient requirements, and species interactions.     

鸡粪改良铜尾矿对3种豆科植物生长及基质微生物量和酶活性的影响

基质改良和耐性植物种选择是重金属矿业废弃地人工生态恢复的关键。通过室内盆栽试验研究不同比例腐熟鸡粪改良铜尾矿后对3种豆科植物决明(Cassia tora)、田菁(Sesbania cannabina)、菽麻(Crotalaria juncea)生长和尾矿基质中土壤微生物量C、N及过氧化氢酶、碱性磷酸酶、脲酶和脱氢酶活性的影响。结果表明:添加鸡粪改良处理后3种植物茎叶生物量、根系生物量和体内总磷含量均有提高,植物体内总氮含量则只有菽麻明显增加。添加鸡粪可提高尾矿基质中微生物量C以及脲酶和脱氢酶活性,其中菽麻生长的尾矿基质中微生物量C含量增加最显著。尾矿基质中微生物量C与基质中总氮、有效磷呈显著正相关,菽麻生长的尾矿基质中微生物量C与基质中有效态Cu、Zn呈显著负相关。田菁、菽麻生长的尾矿基质中脲酶、脱氢酶与基质中总氮、有效磷呈显著正相关,决明、菽麻生长的尾矿基质中脱氢酶与基质中微生物量C呈显著正相关,决明生长的尾矿基质中脲酶、脱氢酶与基质中有效态Zn呈显著负相关。综合分析表明,铜尾矿∶鸡粪=250∶1的处理方式可作为鸡粪改良铜尾矿基质较好的一种比例模式,该处理方式下菽麻可作为铜尾矿生态修复优选植物种。     

Antioxidant activities of three dihydrochalcone glucosides from leaves of Lithocarpus pachyphyllus

In vitro antioxidant activities of three sweet dihydrochalcone glucosides from the leaves of Lithocarpus pachyphyllus (Kurz) Rehd. (Fagaceae), trilobatin 2"-acetate (1), phloridzin (2) and trilobatin (3), were investigated. The IC50 (50% inhibitory concentration) values for compounds 1-3 of lipid peroxidation in rat liver homogenate were 261, 28, 88 microM, respectively. Compounds 1-3 increased superoxide dismutase (SOD) activity with EC50 (50% effective concentration) values of 575, 167, 128 microM, and glutathione peroxidase (GSH-Px) activity with EC50 values of 717, 347, 129 microM, respectively, and showed only weak DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity.     

Plant-type dependent changes in arbuscular mycorrhizal communities as soil quality indicator in semi-arid Brazil

A large remaining of dry deciduous forest (woody Caatinga) in semi-arid Brazil has been reached by successive fires and exploratory actions what leads to the invasion of low load trees and shrub mesh, called “Carrasco vegetation”. As it restrains the sprouting of woody species, land recuperation was performed using a mixed plantation of native and Eucalyptus species to both preservation and to supply the demand for wood. In order to evaluate the recuperation, a study of microbial communities was proposed. In addition to the highest soil phosphorus content found in the Carrasco area, the greatest spore density of arbuscular mycorrhizal fungi (AMF) communities occurred in the rhizosphere of the both pioneer species: Carrasco and Eucalyptus. In contrast to the DGGE bacteria profile, it was possible to group AMF species of the preserved and experimental sites which were not clustered with Carrasco species through the DGGE of Glomales DNA and also by the principal component analysis (PCA) based on diversity index. Glomus and Acaulospora were the dominant genera at both the preserved site and Carrasco. Nevertheless, Gigaspora species were preferentially found in Dry Forest, while Scutellospora were absent. In contrast, Carrasco favoured the genus Scutellospora and the species Acaulospora scrobiculata. Our results allow one to conclude that vegetation type modifies the AMF communities, which may be used as good indicator of soil quality. Based on AMF communities as soil quality indicator, the mixed forest plantation appears to be underway towards the preserved site two years after transplantation.     

Antioxidant enzyme activities and trace element concentrations in ischemia-reperfusion

In this study, we investigated the impact of ischemia-reperfusion on antioxidant enzyme activities and trace element concentrations. For this purpose, ischemia was initiated by clamping superior mesenteric artery of Wistar (albino) rats for 30 min, followed by reperfusion for 20 min. Immediately after reperfusion, blood samples were taken and examined for red cell copper-zinc superoxide dismutase (Cu-Zn-SOD), catalase (CAT), and glutathione peroxidase (GPx) activities spectrophotometrically and plasma zinc, copper, and magnesium concentrations by atomic absorption spectrophotometer. In the ischemiareperfusion group, red cell Cu-Zn-SOD activity and plasma zinc and copper concentrations were increased significantly (p<0.001) when compared to the control group; however, the increases in GPx activity and plasma magnesium concentration were not significant (p>0.05). We also found a significant (p<0.01) decrease in catalase activity. Free radicals released as a consequence of ischemia-reperfusion caused significant alterations in antioxidant enzymes and in the concentrations of trace elements. Presented at III International Congress of Pathophysiology 1998, Lahti, Finland.