魏源诗学思想与湖湘地域文化——以《诗古微》、《诗比兴笺》为论述中心

魏源是晚清经世致用学术思想的有力提倡者和实践者,是来自湖湘的有识之士。《诗古微》和《诗比兴笺》是魏源的两部重要学术著作,前者是一部经学研究著作,后者是一部特色鲜明、具有诗论性质的诗选,却集中体现了魏源的诗学思想。这两部著作表明,魏源的诗学思想除受当时今文经学思潮影响之外,还深受湖湘地域文化传统的熏染,后者的影响作用主要表现在三个方面：对先秦屈骚的崇拜与追慕,对清初王夫之《诗广传》的大量引用,以及对近代湖湘经世学风的自觉传承。     

国家森林公园发展塞罕坝生态旅游的优势与前景预测

本文分析了塞罕坝开展生态旅游的旅游优势、自然景观优势、人文景观优势、生物景观优势,并对生态旅游前景预测,旨在为国内森林公园的生态旅游资源开发提供借鉴。     

“田园城市”美学思想与意境设计研究——以“成都·世界田园城市”为例

从田园城市概念产生的背景、田园城市的理论与实践、对国内外城市规划中的影响、成都建设田园城市所具备的条件这4个方面阐述了田园城市在“成都·世界田园城市”意境规划设计中的指导作用.通过对研究内容的分析,总结出田园城市理论在成都建设城市规划中的美学价值:可形成大面积的绿色视野,营造成都独特的休闲文化气息,构建田园意象、自然文化景观多样性的统一.     

Species richness of ectomycorrhizal hyphal necromass increases soil CO2 efflux under laboratory conditions

The ectomycorrhizal mycelium is a large component of boreal and temperate forest soil microbial biomass and the resulting necromass is likely to be an important source of nutrients for saprotrophic microorganisms. Here we test the effects of species richness of ectomycorrhizal mycelial biomass on short-term CO₂ efflux by amending forest soil with necromass from 8 fungal species added separately and in mixtures of 2, 4 and 8 species. All additions of necromass rapidly increased soil CO₂ efflux compared to unamended controls but CO₂ efflux increased significantly with species richness. Efflux of CO₂ did not correlate with the carbon (C) or nitrogen (N) contents or the C:N ratio of the added necromass. The study demonstrates that species diversity of dead ectomycorrhizal fungal hyphae can have important consequences for soil CO₂ efflux, and suggests decomposition of hyphae is regulated by specific constituents of the nutrient pools in the necromass rather than the total quantities added.     

Long term impact of mineral amendment on the distribution of the mineral weathering associated bacterial communities from the beech Scleroderma citrinum ectomycorrhizosphere

Liming is a known forest management procedure used to amend nutrient-poor soils such as soils of acidic forests to rectify cation deficiencies and to restore soil pH. However, although this procedure is well known for its beneficial effect on the forest trees, its relative impact on the functional and taxonomic diversity of the soil bacterial communities has been poorly investigated. In this study, we characterized the ability of the soil bacteria to weather soil minerals and to hydrolyze chitin. A collection of 80 bacterial strains was isolated from the Scleroderma citrinum ectomycorrhizosphere and the adjacent bulk soil in two stands of mature beeches (Fagus sylvatica) developed on very acidic soil and presenting two levels of calcium (Ca) availability: a control plot as well as a plot amended with Ca in 1973. All the bacterial isolates were identified by partial 16S rRNA gene sequence analysis as members of the genera Burkholderia, Bacillus, Dyella, Kitasatospora, Micrococcus, Paenibacillus, Pseudomonas, and Rhodanobacter. Using a microplate assay for quantifying the production of protons and the quantity of iron released from biotite, we demonstrated that the bacterial strains from the amended plot harbored a significant higher mineral weathering potential that the ones isolated from the control plot. Notably, the weathering efficacy of the ectomycorrhizosphere bacterial isolates was significantly greater than that of the bulk soil isolates in the control treatment but not in the amended plot. These data reveal that forest management, here mineral amendment, can strongly affect the structure of bacterial communities even over the long term.     

Empirical modeling of spatial and temporal variation in warm season nocturnal air temperatures in two North Idaho mountain ranges, USA

Accurate, fine spatial resolution predictions of surface air temperatures are critical for understanding many hydrologic and ecological processes. This study examines the spatial and temporal variability in nocturnal air temperatures across a mountainous region of Northern Idaho. Principal components analysis (PCA) was applied to a network of 70 Hobo temperature loggers systematically distributed across 2 mountain ranges. Four interpretable modes of variability were observed in average nighttime temperatures among Hobo sites: (1) regional/synoptic; (2) topoclimatic; (3) land surface feedback; (4) canopy cover and vegetation. PC time series captured temporal variability in nighttime temperatures and showed strong relationships with regional air temperatures, sky conditions and atmospheric pressure. PC2 captured the topographic variation among temperatures. A cold air drainage index was created by predicting PC2 loadings to elevation, slope position and dissection indices. Nightly temperature maps were produced by applying PC time series back to the PC2 loading surface, revealing complex temporal and spatial variation in nighttime temperatures. Further development of both physically and empirically based daily temperature models that account for synoptic atmospheric controls on fine-scale temperature variability in mountain ecosystems are needed to guide future monitoring efforts aimed at assessing the impact of climate change.     

Drought and ecosystem carbon cycling

Drought as an intermittent disturbance of the water cycle interacts with the carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequences for carbon uptake by photosynthesis and release by total ecosystem respiration. After a drought the disturbances in the reservoirs of moisture, organic matter and nutrients in the soil and carbohydrates in plants lead to longer-term effects in plant carbon cycling, and potentially mortality. Direct and carry-over effects, mortality and consequently species competition in response to drought are strongly related to the survival strategies of species. Here we review the state of the art of the understanding of the relation between soil moisture drought and the interactions with the carbon cycle of the terrestrial ecosystems. We argue that plant strategies must be given an adequate role in global vegetation models if the effects of drought on the carbon cycle are to be described in a way that justifies the interacting processes.     

关于森林经理学的正名,定位与开拓

森林经理学二字的释义,不一定视为经营与管理二词的缩写,而应是度量与筹划,森林经理学是森林资源度量与筹划的技术科学。     

天然次生林群落垂直结构的定量研究

本文以三个次生林群落类型为对象,运用相对多度(RA)、相对频度(RF)、相对显著度(RD)及重要值(Ⅳ)等指标,对其垂直结构进行了深入分析,运用填充系数(F)对群落的层次结构研究提供重要依据;在参考多种分层系统的基础上运用动态的分层方法对群落的层次结构进行了较为合理的划分;分析了次生林群落的垂直结构特征对于群落生产力及其动态演替趋势的意义.     

皖东低丘陵地复合经营系统的探讨

本文探讨皖东地区低丘陵地建立复合经营系统的模式;重点在于进入模式中的林下混种作物的研究以及不同林分下混种效果的比较,对刺槐林分中混种绞股蓝植物的可能性和经济效益作了比较详细的分析,通过二年的比较栽培表明该种模式稳定高产,可在皖东地区推广。