大熊猫对冷箭竹更新竹林与残存竹林的选择利用及微生境结构的比较

在四川卧龙国家级自然保护区大熊猫Ailuropoda melanoleuca活动密集的"五一棚"区域,设置固定监测样线,定期收集大熊猫在冷箭竹更新竹林和残存竹林中的活动痕迹和生境数据。通过路线监测和样地调查,"五一棚"区域拐棍竹和冷箭竹为海拔梯度分布,2700 m以下为拐棍竹林,2300~3600 m之间为冷箭竹林;冷箭竹的更新竹林和残存竹林呈镶嵌耦合分布,从而有利于大熊猫的季节迁徙、食物转换和面对冷箭竹的开花枯死和自然更新。2012年9月—2013年11月的监测数据表明野生大熊猫主要生活于更新竹林中,利用率达到91.94%,且不同月份之间具有波动性(P<0.05)。比较更新竹林和残存竹林的微生境结构,发现两者之间除小部分变量之外(坡度、灌木层盖度、草本层盖度、竹笋密度、成竹密度、种群密度和枯死竹密度),其余各变量之间差异均无统计学意义(P>0.05),且竹子质量(地径、株高和生物量)达到大熊猫选择利用的标准。     

Review of Carbon Fixation in Bamboo Forests in China

Bamboo is widespread in the subtropics and tropics of Asia, Africa, and Latin America. The total area of bamboo forests of various species is 22.0?×?10⁶ ha, accounting for about 1.0% of the total global area of forest. Although the total forest areas in many countries have decreased drastically, bamboo forests have increased at a rate of 3% annually. China has the richest resources of bamboo in the world, with over 500 species in 39 genera. Carbon storage of vegetation, soils, and litter in bamboo forest system in China was 0.2511?×?10¹⁵, 0.8516?×?10¹⁵, and 0.0361?×?10¹⁵ g C, respectively, giving a total of 1.1388?×?10¹⁵ g C. This paper reviews carbon storage of vegetation, soils, and litter in bamboo forest system and compares the carbon fixation abilities of bamboo forest ecosystems with those of other tree species in subtropical China.     

带状采伐毛竹林恢复的质量特征研究

以安徽省黄山区毛竹林样地内2018年春笋和新竹为研究对象,以传统择伐林为对照(CK),设置4个梯度的采伐强度,分别为3m采伐带(D1)、6m采伐带(D2)、9m采伐带(D3)和12m采伐带(D4),分析带状采伐后毛竹林主要生产力指标(春笋数量、新竹数量、胸径和生物量等)的差异,探讨不同强度带状采伐方式对毛竹林恢复更新的影响程度,为毛竹林合理带状采伐提供理论依据。结果表明:(1)4种带状采伐处理单位面积发笋数量均大于对照,且随采伐强度增加,单位面积发笋数量呈现增加的趋势;较高采伐强度(9m和12m采伐带)下单位面积退笋数量和退笋率比采伐强度较低处理(3m和6m采伐带)和CK更低;单位面积成竹数量和成竹率以较高采伐强度(9m和12m采伐带)处理下相对较高。(2)4种带状采伐处理的新竹平均胸径均小于对照,较高采伐强度(9m和12m采伐带)下新竹平均胸径显著小于母竹,林地中小径级新竹比例增加,且新竹胸径与采伐带边距呈负相关关系。(3)4种带状采伐处理下单位面积新竹地上生物量均小于对照,表现为CK>D3>D4>D2>D1。研究认为,毛竹林恢复的质量特征对不同强度带状采伐措施存在响应差异,6~9m采伐带的毛竹林恢复能力较强,但毛竹林带状采伐后恢复是一个周期性过程,需要综合考虑不同强度带状采伐措施对新竹质量影响的长期效应。     

Surrounded by mycobacteria: nontuberculous mycobacteria in the human environment

A majority of the Mycobacterium species, called the nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens. A cardinal feature of mycobacterial cells is the presence of a hydrophobic, lipid-rich outer membrane. The hydrophobicity of NTM is a major determinant of aerosolization, surface adherence, biofilm-formation, and disinfectant- and antibiotic resistance. The NTM are oligotrophs, able to grow at low carbon levels [>50 μg assimilable organic carbon (AOC) l⁻¹], making them effective competitors in low nutrient, and disinfected environments (drinking water). Biofilm formation and oligotrophy lead to survival, persistence, and growth in drinking water distribution systems. In addition to their role as human and animal pathogens, the widespread distribution of NTM in the environment, coupled with their ability to degrade and metabolize a variety of complex hydrocarbons including pollutants, suggests that NTM may be agents of nutrient cycling.     

Surrounded by Slit--how forebrain commissural axons can be led astray.

In Drosophila, Slit acts as a barrier preventing roundabout expressing axons from entering the midline and sorting contralaterally from ipsilaterally projecting axons. Hutson and Chien, Plump et al., and Bagri et al. (all in this issue of Neuron) use Slit knockout mice and zebrafish astray/Robo2 mutants to show that in vertebrates, Robo/Slit function to channel axons into specific pathways and determine where decussation points occur. Ipsilaterally and contralaterally projected axons are equally affected.     

Unveiling a Ghost of Amazonian Rain Forests: Camponotus mirabilis,Engineer of Guadua Bamboo1

Camponotus mirabilis (Hymenoptera: Formicidae) is a highly specialized resident of live Guadua bamboo in western Amazonia. Workers in established colonies open and invade young, unlignified culms, and mature polydomous colonies occupy several‐to‐many adjacent stems. Multistoried carton shelves support brood inside culms, and larvae are nourished by honeydew of coccids (Cryptostigma guadua). Constructing a system of stem holes and wicks, C. mirabilis modifies occupied stems in ways that produce passive water evacuation. Nocturnally foraging workers gather both prey and wood fiber, a component of wicks. Diurnally, they boil aggressively from agitated stems, and are attacked by parasitic phorid flies (Diptera: Phoridae). Culms housing C. mirabilis are stouter and more erect than are unoccupied stems but are opened regularly by capuchin monkeys (Cebus apella) searching for brood and perhaps reproductive castes. Damaged by monkeys, weak‐walled Guadua stems frequently collapse and are abandoned by ants. Breakdown of brood shelves leaves nutrient‐rich carton suspended in water within basal internodes, but isotopic analyses fail to show that occupied culms utilize either nitrogen from carton or carbon respired by ants or decomposing debris. Lower foliar nitrogen concentration in occupied than in control stems suggests that coccids and ants parasitize host resources. A prior experimental survey of bamboo ants may have missed C. mirabilis because females found new colonies in culms occupied by another bamboo specialist, and established colonies invade only young bamboo growth.     

Extending biochemical databases by metabolomic surveys

Metabolomics can map the large metabolic diversity in species, organs, or cell types. In addition to gains in enzyme specificity, many enzymes have retained substrate and reaction promiscuity. Enzyme promiscuity and the large number of enzymes with unknown enzyme function may explain the presence of a plethora of unidentified compounds in metabolomic studies. Cataloguing the identity and differential abundance of all detectable metabolites in metabolomic repositories may detail which compounds and pathways contribute to vital biological functions. The current status in metabolic databases is reviewed concomitant with tools to map and visualize the metabolome.     

A Nanocapsule Based on Natural Mineral Clinoptilolite Surrounded by a Lecithin Envelope

Biophysics - A technology for obtaining nanoparticles of natural clinoptilolite, a mineral from the zeolite family, under laboratory conditions has been developed. The size of zeolite particles was...     

Resonant Broadband Field Enhancement in Cylindrical Plasmonic Structure Surrounded by Perovskite Environment

We demonstrate the optical response of metal nanoparticles and their interaction with organic-inorganic perovskite (methyl ammonia lead halide (CH₃NH₃PbI₃)) environment using discrete dipole approximation (DDA) simulation technique. Important optical properties like absorption, scattering, and electric field calculations for metal nanoparticle using different geometry have been analyzed. The metal nanoparticles embedded in the perovskite media strongly support surface plasmon resonances (SPRs). The plasmonic interaction of metal nanoparticles with perovskite matrix is a strong function of MNP’s shape, size, and surrounding environment that can manipulate the optical properties considerably. The cylindrical shape of MNPs embedded in perovskite environment supports the SPR which is highly tunable to subwavelength range of 400–800 nm. Wide range of particle sizes has been selected for Ag, Au, and Al spherical and cylindrical nanostructures surrounded by perovskite matrix for simulation. The chosen hybrid material and anisotropy of structure together make a complex function for resonance shape and width. Among all MNPs, 70-nm spherical silver nanoparticle (NP) and cylindrical Ag NP having diameter of 50 nm and length of 70 nm (aspect ratio 1.4) generate strong electric field intensity that facilitates increased photon absorption. The plasmonic perovskite interaction plays an important role to improve the absorption of photon inside the thin film perovskite environment that may be applicable to photovoltaics and photonics.