Positionality and protocol in field research: Undertaking community‐based investigations in Samoa

This article considers the experiences of a Samoan female geographer undertaking community‐based field research in her home country, and identifies some lessons for researchers working in similar circumstances. The paper suggests that ethical behaviour in research is ‘place‐specific’, and there is therefore a need to employ culturally sensitive and ‘location‐specific’ methodologies when undertaking community‐based research fieldwork. For the lead researcher, growing up in Samoa played a significant role in gaining an understanding of a set of robust and effective procedures to evaluate citizens' resilience to climatic and other environmental challenges. Fluency in everyday and more formal local languages, and awareness of local differences, each with multi‐layered connections to local communities, understanding cultural nuances and practising respect for va tapuia [sacred space or relationships] protocols, together facilitated the process of knowledge acquisition and helped to confirm the validity of the conclusions derived from the study.     

基于高通量测序技术分析2种菌草根际土壤真菌群落多样性

为了解福州菌草基地巨菌草和绿洲一号2种菌草的根际土壤真菌群落多样性,采用Illumina Miseq高通量测序技术和生物信息学方法,对菌草根际土真菌的多样性及群落结构进行分析。结果表明：从3份土壤样本中获得525 292条ITS序列,在97%序列相似性基础上可划分为7267个可操作分类单元（OTU）。真菌群落的丰富度指数（ACE）以菌草非根际土最低,绿洲一号根际土略高于巨菌草根际土;而多样性指数（Shannon-Wiener和Simpson）菌草根际土高于非根际土,绿洲一号根际土略高于巨菌草根际土。3份样品的优势菌门为子囊菌门（Ascomycota）、担子菌门（Basidiomycota）、接合菌门（Zygomycota）、壶菌门（Chytridiomycota）、球囊菌门（Glomeromycota）;优势菌纲为散囊菌纲（Eurotiomycetes）、粪壳菌纲（ Sordariomycetes）、座囊菌纲（Dothideomycetes）、伞菌纲（Agaricomycetes）、锤舌菌纲（Leotiomycetes）、圆盘菌纲（Orbiliomycetes）、银耳纲（Tremellomycetes）、粘膜菌纲（Wallemiomycetes）;优势菌属为篮状菌属（Talaromyces）、深黄伞形霉属（Umbelopsis）、枝孢菌属（Cladosporium）、暗双孢菌属（Cordana）、镰刀菌属（Fusarium）、隐球菌属（Cryptococcus）、淡紫紫霉属（Purpureocillium）、赤霉菌属 （Gibberella）、灵芝属（Ganoderma）。研究结果表明,菌草根际土真菌群落多样性高于非根际土,为进一步更好地利用菌草提供理论参考依据。     

间作栽培对宁夏南部山区马铃薯根际土壤真菌菌群结构的影响

根据宁夏南部山区气候和作物的生长特点，设计马铃薯‖玉米（P‖M，行比分别为4∶1，3∶2， 2∶3）、马铃薯‖蚕豆（P‖F，行比同前）、马铃薯不同品种（A‖B‖C，行比1∶1∶1）间作栽培模式，以马铃薯连作为对照，研究马铃薯根际土壤真菌多样性和菌群结构的变化，探寻能够减轻宁夏南部山区马铃薯连作障碍的有效栽培模式。采用基于18S rDNA的末端标记限制性片段长度多态性 (Terminal restriction fragment length polymorphism，T-RFLP) 技术研究不同间作栽培模式下马铃薯根际土壤真菌的菌群结构和多样性变化，构建真菌ITS克隆文库，利用Genbank数据库比对各栽培模式中ITS序列的测序结果，并作群落结构组成和功能分析。结果表明，马铃薯间作栽培后真菌Shannon-Wiener指数和Simpson指数均有不同程度降低；马铃薯与玉米、蚕豆间作后根际土壤真菌的物种丰富度在门、纲和目的分类学水平上与连作相比明显下降，菌群结构发生较大变化，成熟期马铃薯‖玉米3∶2行比间作模式与连作的差异最大，属的比例下降67.74%。间作栽培后，黑孢属（Nigrospora）、地丝霉属（Geomyces）、圆盘菌属（Orbilia）、枝顶孢属（Acremonium）、四枝孢属（Tetracladium）等9个属的真菌消失，同时新增刺盘孢属（Colletotrichum）、毛壳属（Chaetomium）、巨孢囊霉属（Gigaspora）、小球腔菌属（Pleosporineae）等13个属的真菌，其中马铃薯‖玉米3∶2行比间作后巨孢囊霉属比例高达60.35%。可见，马铃薯‖玉米间作栽培能有效改善马铃薯根际土壤的真菌菌群结构，使其微环境得以改善，缓解宁夏南部山区马铃薯连作障碍。     

Artificial neural network modeling of microbial community structures in the Atlantic Forest of Brazil

Microbial communities vary across the landscape in forest soils, but prediction of their biomass and composition is a difficult challenge due to the large numbers of variables that influence their community structures. Here we examine the use of artificial neural network (ANN) models for extraction of patterns among soil chemical variables and microbial community structures in forest soils from three regions of the Atlantic Forest of Brazil. At each location, variations in soil chemical properties and FAME profiles of microbial community structures were mapped at 20 × 20 m intervals within 10 ha parcels. Geostatistical analyses showed that spatial variability in soil physical and chemical variables could be mapped at scale distances of 20 m, but that FAME profiles representing the microbial communities were highly variable and had no spatial dependence at the same scale in most cases. RDA analysis showed that FAME signatures representing different microbial groups were positively associated with soil pH, OM, P and base cations concentrations, whereas microbial biomass was negatively associated with the same environmental factors. In contrast, ANN models revealed clear relationships between microbial community structures at each parcel location, and generated verifiable predictions of variations in FAME profiles in relation to soil pH, texture, and the relative abundances of base cations. The results suggest that ANN modeling provides a useful approach for describing the relationships between microbial community structures and soil properties in tropical forest soils that were not able to be captured using geostatistical and RDA analyses.     

不同植被恢复模式土壤结构特征与健康评价

对湘西女儿寨流域不同植被恢复类型的土壤结构特征研究和健康评价的结果表明:荒草灌丛容重最高,人工林土壤容重高于天然林及混交林;对土壤孔隙状况的改善作用表现为林分类型优于荒草灌丛类型,天然林优于人工林,0~20 cm土层优于20~40 cm土层;土壤团聚体平均重量直径以油桐人工林、杜仲人工林最高,马尾松天然林、毛竹杉木混交林其次,而润楠次生林、荒草灌丛、杉木人工林较低;各层土壤团聚体分形维数值大小排序为:毛竹杉木混交林>马尾松天然林>荒草灌丛、润楠次生林>杜仲人工林>油桐人工林>杉木人工林;土壤结构健康综合评价的灰色关联分析结果表明,土壤结构以荒草灌丛最差,油桐人工林最好,其余类型介于两者之间.研究结果可为女儿寨流域及我国类似生态脆弱区的植被恢复与重建提供一定依据和参考.     

湘中丘陵区石栎混交林群落物种多样性研究

通过对湘中丘陵区石栎（Ｌｉｔｈｏｃａｒｐｕｓｇｌａｂｅｒ（Ｔｈｕｎｂ．）Ｎａｋａｉ）混交林群落调查．利用Ｓｈａｎｎｏｎ和Ｓｉｍｐｓｏｎ多样性指数及相应的均匀度和种间相遇机率．对其群落物种的多样性进行了初步研究．结果表明：湘中丘陵区石栎混交林群落乔木层与下木层的Ｓｈａｎｎｏｎ多样性指数分别为１．１８４和３．１９７；Ｓｉｍｐｓｏｎ多样性指数分别为０．６２４和０．８１４；种间相遇机率分别为０．６２５和０．８１４；均匀度分别为４５．８０％和６３．９４％．乔木层第Ⅰ亚层多样性指数低于第Ⅱ亚层；群落的物种多样性是时间和空间的函数．     

甜槠群落主要种群空间分布格局对人为干扰的响应

研究了不同人为干扰强度对甜槠天然群落中主要种群甜槠和赤楠的分布格局的变化动态.结果表明,人为干扰会使甜槠种群的聚集性加强,而赤楠种群的聚集性降低.干扰强度对甜槠聚集性的影响随树龄的增大而逐渐减小,而对赤楠聚集性的影响则是随林龄增大呈现由小→大→小的规律.     

Rain Use Efficiency,Primary Production and Rainfall Relationships in Desert Rangelands of Tunisia

Desert rangelands are characterised by low and highly variable rainfall regime, low forage production and high heterogeneity in the distribution of natural resources. This study was carried out in the desert rangelands of Tunisia to evaluate the response of different rangelands to annual rainfall in terms of aboveground net primary production (ANPP) and rain use efficiency over a 10‐year period (2003–2012). In general, ANPP values were relatively low (123 kg DM ha⁻¹ y⁻¹) but would tend to increase with increasing annual rainfall for all rangeland types. The highest value of ANPP was observed from Stipagrostis pungens and Hammada shmittiana communities (sandy‐soil) during the wet year 2011. In contrast, rain use efficiency tends to decline with the highest annual rainfall and varies among rangeland types and with an average of 1·9 kg DM ha⁻¹ mm⁻¹ y⁻¹. Rain use efficiency tended to be higher during dry years and lower during wet years and tended to be higher on S. pungens and H. shmittiana (sandy‐soils) and lower on Helianthemum kahiricum (loamy soils). Therefore, understanding how rainfall affects productivity in rangelands is critical for predicting the impact of land degradation on the functioning of these ecosystems. It can be used to explain production decline associated with desertification as well as to assess rangeland conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

Traditional weather forecasting for sustainable agroforestry practices in Ilocos Norte Province,Philippines

People in rural communities in Ilocos Norte Province in the Philippines rely heavily on traditional knowledge, particularly for predicting weather to plan and prepare their agroforestry activities as well as disaster prevention. Farmers use this knowledge, derived from observations of atmospheric and astronomic conditions, indicator plants and behavior of animals (insects, birds, and mammals) which signal the onset of the rainy season. These indicators prompt farmers to prepare their upland farmlands for cropping to ensure that vegetative ground cover is established prior to heavy rainfall and thereby prevent erosion of upland soil and siltation of watercourses. Predictive knowledge of the timing of long or short rainy periods enables farmers to plant suitable crops.     

Soil conditions and land use intensification effects on soil microbial communities across a range of European field sites

Intensive land use practices necessary for providing food and raw materials are known to have a deleterious effect on soil. However, the effects that such practices have on soil microbes are less well understood. To investigate the effects of land use intensification on soil microbial communities we used a combined T-RFLP and pyrosequencing approach to study bacteria, archaea and fungi in spring and autumn at five long term observatories (LTOs) in Europe; each with a particular land use type and contrasting levels of intensification (low and high). Generally, due to large gradients in soil variables, both molecular methods revealed that soil microbial communities were structured according to differences in soil conditions between the LTOs, more so than land use intensity. Moreover, variance partitioning analysis also showed that soil properties better explained the differences in microbial communities than land use intensity effects. Predictable responses in dominant bacterial, archaeal and fungal taxa to edaphic conditions (e.g. soil pH and resource availability) were apparent between the LTOs. Some effects of land use intensification at individual field sites were observed. However, these effects were manifest when land use change affected soil conditions. Uniquely, this study details the responses of different microbial groups to soil type and land use intensification, and their relative importance across a range of European field sites. These findings reinforce our understanding of drivers impacting soil microbial community structure at both field and larger geographic scales.