Population differentiation of Procypris rabaudi (Tchang) in the upper reaches of the Yangtze River revealed by mitochondrial DNA and RAPD markers

Procypris rabaudi (Tchang) is a cyprinid fish endermic to middle and upper reaches of the Yangtze River. Besides in main stream and large tributaries, there exists an early matured, small-sized ecological type in a small tributary, Tang River. In this study, mitochondrial DNA cytochrome h (cyt b) gene sequence analysis and randomly amplified polymorphic DNA (RAPD) analysis were performed to investigate the differentiation of the Tang River population from the Mudong reach population of the Yangtze River, with the purpose of conservation and exploitation of this fish. In the 1140 bps of cyt b gene sequence surveyed, 20 sites were found polymorphic, which defined 23 haplotypes. Among them, four haplotypes accounted for 54.4% of all individuals, while population-specific haplotypes occurred in low frequencies. Analysis of molecular variation on cyt b data revealed no significant partition existing between Tang River population and Mudong reach population. Analyses of 132 RAPD loci suggested that genetic variation between populations was significant, though values of different F-ST were not very high. The results revealed low genetic diversity and the beginning of population differentiation, suggesting that Tang River population should be designated as a separate Management Unit.

Population genetic structure of an endemic cyprinid fish, Ancherythroculter nigrocauda, in the upper reaches of the Yangtze River and its implication for conservation

Ancherythroculter nigrocauda is a cyprinid fish endemic to the upper reaches of the Yangtze River, which has been reported to have 2 or 3 chambers to its air bladder. Morphological studies showed no differences between individuals with different types of air bladder, but did demonstrate geographical differences from different sources. After the completion of the Three Gorges Dam, it was expected that the population of this species would decrease, but artificial breeding and stocking is under consideration to protect this species from extinction. In the present study, mtDNA cytochrome b gene sequences were determined and analyzed for A. nigrocauda samples of different morphotypes and sources to identify their genetic differentiations, and thereby guide plans for the artificial propagation and conservation of this species. Haplotype diversity index values (h) and nucleotide diversity values (pi) for all the populations were found to be high indicating their high level genetic diversity. An analysis of molecular variance identified no differentiation among the studied populations. Therefore, we suggested that the individuals of different morphological types and geographical sources belong to the same species. To maintain its high level genetic diversity, it mill he necessary to use large and diverse sources of parental fish for artificial reproduction.

Findings report on the endemic fluorosis in the lower reaches of Xiaoqing river [小清河下游地区地方性氟中毒调查报告]

Objective: To find out the present prevalent situation of the endemic fluorosis in the lower reaches of Xiao Qing River , and to look for an effective way to altering sources to lower fluoride level. Methods: To determine the water fluoride content in the drinking water sources and investigate the basic condition of the water sources (type of the water sources, the depth of well, etc) in the three towns of this area . Make a sampling survey of the children aged from 8 to 12 about the dent al fluoro sis and determine the urine fluoride, and the skeletal fluorosis among the crowd over 16 y ears of age. Results: The survey shows that the lower reaches of Xiaoqing river belong to the drinking water type of endemic fluorosis caused by drinking deep well water. In this area, 65.71% of the water sources contain high level of fluoride, 57.51% of the children suffer from dental fluorosis, 0.58% of the crowd over 16 years of age suffer from skeletal fluorosis. High water fluoride rate is related with the depth of the well. If the well is over 500 metres deep, the fluoride content rate is clearly low. Conclusions: In this area, there are still some water sources which contain normal level of fluoride. By increasing the depth of the well down to 500 metres, the problem of high fluoride in water might be solved.

Organic carbon in the sediments of the lower reaches of Periar River

Sediments are indicators of the quality of water overlying them and hence, useful in the assessment of environmental pollution. Temporal and spatial variations in sediment characteristics and organic carbon content from 9 stations in the lower reaches of Periyar River an area in Cochin Backwater, India which is polluted from different sources were studied for one year during 1981. Variations in colour and texture of sediments were brought about by changes in the grain size and state of oxidation of organic matter. The colour of the sediment varied from greyish black at stations 1 and 2, brownish at station 3, black at stations 4 to 8 and reddish at station 9. Organic carbon and sediment texture showed a direct relationship at all stations except at station 9 where organic carbon content showed an irregular pattern. Overall range of organic carbon content was between 1.19 and 29.6 mg.g super(-1). The mean organic carbon of the stations ranged between 6.8 mg.g super(-1) (station 5) and 20.8 mg.g super(-1) (station 9). On the whole temporal variations were considerable with high values at station 9 and low values at station 5. Fluctuations were more at stations 6, 7 and 8.

On the growth and reproductive biology of asp, Aspius vorax, population from the middle reaches of Euphrates river

Endemic asp, Aspius vorax, from the middle section of the Euphrates River flowing through eastern Syria were studied to determine the main characteristics of their population structure, morphological parameters and reproductive biology. Samples ranged between 0+ and 4+ years of age and were dominated by 2+ years old group. Total length (TL) ranged between 19 and 70 cm corresponding with 46 to 2824.5 g weight, respectively. Fish growth has isometric pattern and the overall sex ratio was unbiased. Seasonal changes in the condition factor were related with the water temperature as well as the spawning season. Annual cycle of gonadosomatic index (GSI) readings indicated that spawning season occur around March when fish longer than 36 cm can mate. Average pre-spawning GSI was greater in individuals older than 2 years. Meanwhile, female fecundity was highly related to TL and weight. These findings did not always concur with previous observations from other asp populations, mainly in southern and northern Mesopotamia. Our results highlighted basic biological aspects of the local population and indicated differences between populations which can assist in fisheries management, conservation and commercial culture of the investigated species.

Dynamics And Speciation Of The Heavy Metals In The Lower Reaches Of Chithrapuzha- A Tropical Tidal River

The proposed study is an attempt to quantify and study the seasonal and spatial variations in the distribution of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb among the various geochemical phases in the surficial sediments of Chitrapuzha river. The study also estimates the concentration of heavy metals in dissolved, particulate and sediments and their variation in seasonal and spatial distribution. Chitrapuzha River originates as a small stream from the upper reaches of high ranges in the eastern boundary of Kerala, passes through the valley and finally joints in the Cochin backwaters. Numerous industrial units located along the banks of the river discharge treated and untreated effluents into the water. These are long standing local complaints about water pollution causing fish mortality and serious damage to agricultural crops resulting in extensive unemployment in the area. The river is thus of considerable social and economic importance.

景观格局对土壤侵蚀的影响研究-以岷江上游的小流域为例

岷江上游地区生态环境脆弱，加之不合理的土地利用，土壤侵蚀问题日趋严重。准确定量土壤侵蚀、产沙模数的空间分布，从而分析土地利用及其空间配置对于土壤侵蚀过程是否合理？对减少长江上游的输沙量具有重要意义，是一个严峻的研究课题。本文以GIS为平台，建立泥沙输移分布模型，模拟流域的侵蚀模数、泥沙输移比和产沙模数的空间分布；结合模型模拟结果，分析不同土地利用/覆被方式的侵蚀和产沙特征，并以景观生态学的“格局-过程”理论为基础，通过景观指数——景观空间负荷对比指数，探讨土地利用/覆被的空间格局对土壤侵蚀过程的影响。泥沙输移分布模型模拟的产沙量与实测值比较，结果十分理想。模拟结果表明：两个流域大部分区域属于微度到中度侵蚀，平均侵蚀模数略低于长江上游的平均值；两个流域的平均泥沙输移比均远小于长江上游的平均值；河流两侧1 km范围内是流域主要的产沙区域；不同土地利用/覆被方式的侵蚀模数不同——裸岩>居民点>草地 >农田>灌木林>林地；侵蚀广泛分布在草地、林地和灌木林地上，占流域侵蚀总量的80%以上；灌木林和林地是流域主要的产沙源，占总产沙量的60%以上。景观空间负荷对比指数的计算结果表明：两个流域土地利用/覆被随坡度的空间配置有利于水土保持，但随相对距离、相对高度和运移距离的空间配置不利于水土保持；两个流域“源”大“汇”小的土地利用/覆被组成方式有利于水土保持，且镇江关流域的组成方式更优；景观空间负荷对比指数能够比较全面客观地反映景观格局对对土壤侵蚀过程的影响：两个流域的景观格局均较为合理；且镇江关流域的景观格局优于黑水流域。

岷江上游地区景观格局优化

岷江上游是我国十分典型的山地生态脆弱区。该地区的生态环境意义十分重大，既是长江上游生态屏障的重要组成部分，更是成都平原的重要生态屏障和水源生命线，其生态环境状况直接影响成都平原水资源的质量和数量，以至影响到整个岷江流域甚至整个长江上游的生态环境与社会经济发展。对岷江上游的生态服务和景观格局的变化进行分析和优化得到如下主要结论： 1岷江上游地区近几十年来土地利用发生了很大的变化，农田面积显著增加，森林面积减少，草地有所增加；研究区总体生态服务价值减少了771.11亿元。对岷江上游各时期的生态服务功能经济价值的计算和比较，研究表明应对土地利用结构进行相应的、有区别的调整，实施退耕还林还草，以优化岷江上游地区的生态服务功能，还应该实施计划生育政策；应增加蔬菜瓜果的种植面积，增加当地的经济收入。 2岷江上游地区在1986年水源涵养量最高，1995年水源涵养量下降，造成这一现象的主要原因是20世纪90年代岷江上游森林景观受到人为的严重破坏，1998年实施“天然林保护工程”与“退耕还林还草”的政策，加强了人工造林，改善了森林生态系统，使森林生态系统水源涵养量有所恢复，使得2000年水源涵养量及经济价值与1995年基本持平。 3分布在岷江上游的大中型兽类中，有5种野生动物在此地绝迹。造成这一现象的主要原因是人口的增加、经济的发展使人类对生态环境的压力加大，减少了野生动物的适宜生境。降低了生物多样性，适宜斑块进一步破碎化，核心区面积减少且距离进一步加大。因此，为改善现状，在岷江上游地区应大力推动科技发展，减少人类活动对生态环境的破坏，发展经济与生态保护并重。 4结合灰色线形规划和CLUE-S模型对岷江上游地区的景观格局进行合理规划，结果表明：岷江上游景观格局优化配置应将灌木林地、草地和耕地恢复到林地，综合治理干旱河谷，保持区域经济可持续发展。优化结果有林地面积增加15.38%；灌木林地面积减少最多，减少22.84%；农田减少28.84%和草地减少5.65%；城镇等居民用地有所增加。

岷江上游农林景观边界生态效应分析

景观边界的研究是现代景观生态学研究的重要组成部分，也是国内外研究的热点问题。本文选取崛江上游不同类型的景观边界为研究对一象，根据遥感影像解译和野外实际调查，在研究区内的茂县和理县选取4种景观边界类型共7个样地，以农林景观边界生态过程为切入点，运用移动窗口法和统计分析等对垂直于边界方向的土壤水分、土壤养分和植物多样性进行研究，并探索不同因子的影响域以及土壤水分、养分和植物多样性的藕合关系。通过揭示斑块尺度上林地和农田相互作用的强度和范围，刻画农林复合景观的生态环境效应，从而为更大尺度上农林景观的区域环境效应提供科学依据。主要结论如下：（l）景观边界土壤水分变化规律：干旱河谷区土壤水分含量较低，林地一边界，花椒地土壤水分含量基本呈"V'字型变化，而在边界两侧景观的内部呈"W"型波动；日内水分含量从9时-12时-15时依次递减，日间变化干早时不明显，雨后逐曰递减，而年内水分含量变化可以分为上升期，高峰期和消退期；（2）景观边界土壤养分变化规律：从农田一边界一林地只有土壤有机质和全氮含量有明显变化，其它各因子没有明显变化；除全钾、pH值和砾石含量随海拔高度的增加而降低外，土壤全氮、全磷、速效磷、有机质含量随海拔高度的增加而增加；（3）景观边界植物多样性变化规律：各样地乔木树种较为单一，物种丰度主要由灌木和草本的物种数量决定的，各样地草本物种多达60％-80％；边界类型不同所分布的主要植物种类也不同，同一边界类型主要植物种类也有很大差异；（4）景观边界各因子的祸合关系：边界类型不同，多样性指数与土壤因子的锅合关系也不同，对多样性指数影响较大的因子有速效磷、pH、土壤水分和砾石含量；（5）景观边界影响域的定量判定：边界对土壤水分的影响范围随季节变化呈动态变化，干旱条件下约从花椒地6m到林地2m，雨季约从花椒地12m到林地Zm；边界对单一土壤因子有机质的影响域约从林地1.5m-10m，其它单一因子的影响域难以确定，边界对土壤因子综合效应的影响域约从林地2.5m-10m；边界对植物多样性的影响域在林地约为4m-26m，农田约为10m-31m。本研究突破了以往景观生态学"基质一斑块一廊道，，的传统模式，具有创新性。同时，对氓江上游地区农林景观格局优化、改善生态环境具有重要的现实意义。

次生植被土壤碳、氮养分季节动态及凋落物输入与温度的影响

土壤微生物量、可溶性有机碳与氮虽然只占土壤有机碳、氮总量的较小部分，但可以在土壤全碳、氮变化之前反映土壤微小的变化，又直接参与土壤生物化学转化过程，因而在植被恢复过程中，较其它土壤理化性质等能够更好地指示土壤恢复情况。在青藏高原东缘存在大面积的次生人工林替代灌丛或采伐迹地，而关于这些人工林替代后的生态效果和生态过程的评估却十分缺乏，本研究通过评估岷江上游植被恢复重建过程中典型人工替代次生植被凋落物层与土壤碳、氮等养分大小，动态监测土壤微生物生物量、水溶性碳、氮等指标，结合温度与凋落物输入等影响土壤活性有机碳、氮因子的控制试验，系统分析不同人工替代次生植被土壤碳、氮等养分的差异原因，试图寻找低效人工林优化调控与持续管理技术，为区域生态公益林持续管理提供理论和技术依据。主要结论如下： 1. 通过对不同人工替代次生植被凋落物层和土壤碳、氮分析发现，油松和华山松人工林替代次生灌丛后土壤碳、氮含量较灌丛和阔叶人工林低，主要原因可能为凋落物质量(C/N)较差，而引起碳、氮等元素难以归还土壤。进而通过对不同人工替代次生植被凋落物层和土壤微生物生物量、水溶性有机碳、氮等指标的季节性动态模式的分析，发现各次生植被土壤微生物生物量C、N，P以及土壤水溶性碳、氮含量均呈明显季节性动态，呈现秋季明显大于其它季节，冬季最低，在表层土壤最为明显。 2. 油松、华山松人工林凋落物层和土壤水溶性有机碳(WDOC)、土壤水溶性有机氮(WDON)明显低于灌丛和连香树，土壤微生物生物量C、N也以油松和华山松人工林最低，而落叶类植被，如灌丛、连香树和落叶松之间没有明显差异，说明可利用底物的数量和质量差异是影响各次生植被凋落物分解和土壤微生物活性的主要原因。MBC/OC和MBN/ON能较好地指示土壤微生物活性的变化，MBC/OC凋落层总体以灌丛和连香树人工林最高，油松和华山松人工林最低；而土壤中MBC/OC连香树人工最高，华山松人工林最低。说明以油松和华山松为主的人工造林替代乡土阔叶灌丛造成土壤C、N等养分严重匮乏，微生物活性低下是影响其养分周转的主要原因。 3. 从各次生植被凋落物产生看，凋落物年归还量最大的为华山松人工林(5.1×103 kg ha-1)，其次为落叶松人工林(4.8×103 kg ha-1)，阔叶灌丛林地凋落物产生总量(4.4×103 kg ha-1)略大于油松人工林(4.2×103 kg ha-1)，最小的为连香树人工林(3.6×103 kg ha-1)；叶是凋落物的主体，落叶类树种月动态表现为单峰型，高峰主要在10-11月，如落叶松、连香树和灌丛林；常绿的松类月动态不明显，各月基本相同，最为明显地为油松林，华山松人工林略有二个小峰，分别出现在11月和5月。落叶阔叶灌丛的凋落物分解速率大于常绿针叶林，如油松和华山松。结合凋落物的产生量和分解速率，不同树种人工林替代次生阔叶灌丛后，人工油松和华山松林枯落物总贮量和厚度明显大于落叶松人工林、灌丛林和连香树人工林，说明以油松和华山松为主的人工造林替代乡土阔叶灌丛延缓了有机物向土壤的顺利归还，不利于土壤C、N等养分循环。 4. 通过控制地面凋落物和地下根系输入有机物对土壤碳、氮的影响研究发现，(1) 单独去除根系以及根系与地面凋落物同时去除处理1年后对表层(0-10cm)土壤WDOC均没有显著影响，而土壤WDON显著增加，油松人工林土壤微生物生物量C、N显著降低，人工落叶松林没有显著差异，说明油松人工林土壤微生物活性对地下碳输入的依赖大于其它次生植被，而落叶松土壤微生物活性对地下碳输入依赖性较小；去除地面凋落物，明显降低了落叶松人工林土壤WDOC，华山松和连香树土壤WDON均较对照显著减少，油松人工林土壤微生物量C较对照显著减少；双倍增加地面凋落物处理对土壤微生物生物量、WDOC和WDON没有明显地增加，相反，连香树、华山松和油松人工林土壤WDON较对照减少。说明油松人工林微生物活性不仅依赖于地下碳输入，而且对地上有机物输入的依赖性也较大；连香树、落叶松和华山松人工林土壤微生物生物量并没有因地面凋落物的去除减少可能与土壤总有机碳含量及活性均较高有关，而双倍增加地面凋落物反而降低了土壤微生物生物量，说明凋落物覆盖后改变了土壤微气候。 5. 碳矿化累积量与有机碳含量和活性有机碳含量之间存在显著地正相关关系。凋落物碳累积矿化量、矿化速率以连香树最高，油松和华山松人工林次之，落叶阔叶灌丛低于常绿针叶纯林，导致其差异的主要原因可能为凋落物产生的时间动态模式不一样，致使凋落物起始分解时间不一致。而土壤层有机碳矿化速率和矿化量以阔叶落叶灌丛和连香树最高，油松和华山松人工土壤最低，再次证实利用针叶纯林恢复植被阻碍了有机质周转与循环。 6. 凋落物累积矿化量与C/N值呈显著地相关关系，并随着温度的升高而明显增加，而土壤累积矿化量与C/N值没有显著相关关系，说明土壤有机碳质量(C/N)对温度的响应不十分明显。通过双指数模型对不同温度下碳矿化过程进行模拟和计算出活性有机碳与惰性有机碳比例，发现温度升高促进了惰性有机碳向活性有机碳的转化，增加了活性有机碳含量，说明温度升高可促进次生植被凋落物与土壤有机质的分解，进而可影响到林地碳源/汇关系的变化。 综上，通过对不同人工替代次生植被凋落物与土壤C、N大小、以及土壤微生物生物量、水溶性C、N等指标动态变化模式研究，结合温度与凋落物数量输入等影响土壤活性C、N因子的综合分析，以油松和华山松人工纯林对山地植被恢复，延缓或阻碍了有机质周转与循环，造成了土壤肥力退化。对现有低效人工纯林改造，应为地面大量有机物分解创造条件。 Although soil microbial biomass, dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are a small part of total soil organic carbon and nitrogen, they can directly participate in the process of soil biochemical translation and indicate the fine changes before changes of soil total organic carbon and nitrogen occur. So, they are good indexes to indicate soil restoration condition during the process of vegetation rehabilitation. There are large areas of secondary vegetations which substitute for indigenous shrubs in the eastern fringe of Qinghai-Tibet Plateau. However, it is not well known that the ecological effect and process after substitution by different secondary plantations. Based on comparison of soil organic and nitrogen contents in litter layer and soil under different secondary vegetations in upper reaches of Minjiang River, soil microbial biomass, DOC and DON in litter layer and soil were investigated in order to analyze the seasonal dynamic. Combining the effects of temperature, litter input and root exclusion on soil microbial biomass, DOC and DON, we also aim to understand the reason and mechanism of difference in soil carbon and nitrogen contents among different secondary vegetations. The study would contribute to comprehensively understanding C and N cycling processes and provide optimal control and sustainable technology of low-effect plantations in these regions. The results are as follows: (1) Organic carbon and nitrogen in litter layers and soil under different substitution plantations were investigated. The results showed that contents of soil organic carbon and nitrogen were lower in P. tabulaeformis (PT) and P. armandi Franch(PA) than those in native broad-leaf shrub and broad-leaf plantation. The low quality (C/N) of litter in PT and PA plantations caused carbon and nitrogen returning to soil difficultly. Seasonal dynamic of soil microbial carbon (MBC),-nitrogen (MBN),-phosphor (MBP), and WDOC and WDON showed similar pattern, which had the highest values in autumn and the lowest values in winter. (2) WDOC and WDON in litter layers and soil under PT and PA plantations were significantly lower than those in native broad-leaf shrub and Cercidiphyllum japonicum Sieb. et Zucc.(CJ). Soil MBC and MBN were also the lowest, while there were no significant differences among deciduous vegetations, i.e. native broad-leaf shrub, CJ and Larix kaempferi Lamb.(LK) plantation. The results suggested that difference in quantity and quality of available substance was main reason that affected the activity of microbe in soil and litter layer. MBC/OC and MBN/ON were good indexes to indicate the change of soil microbial activity. MBC/OC of litter had the highest value under native broad-leaf shrub and CJ plantation, and had the lowest value in PT and PA plantations, while MBC/OC of soil was the highest under CJ plantation, and was the lowest in PT and PA plantations. These results indicated that PT and PA plantations substituting for native broad-leaf shrub caused deficit of carbon and nitrogen in soil, low microbial activity was a main reason influencing the cycling and turnover of carbon and nitrogen in soil. (3) The annual litter fall production, composition, seasonal dynamic and decomposition of five typical secondary stands in upper reaches of Minjiang River were studied in this paper. The annual litter productions were: PA (5.1×103 kg ha-1), LK(4.8×103 kg ha-1), native broad-leaf shrub (4.4×103 kg ha-1), PT(4.2×103 kg ha-1)，CJ(3.6×103 kg ha-1). The litter production of leaves in five secondary vegetations occupied a higher percentage in the annual total litter production than those of other components. The litterfall was mostly producted in the cool and dry period (October-November) for deciduous vegetations and relatively equably producted in every season for evergreen coniferous vegetations. The decomposition rate of leaf litter in the broad-leaf stand was higher than those in evergreen coniferous stand. Combined with annual litter fall production and decomposition rate of leaf litter, we found that stock and depth of litter layer were significantly larger in PT and PA plantations than those in native broad-leaf shrub, LK and CJ plantations. The results confirmed that PT and PA plantations substituting for native broad-leaf shrub delayed organic matter returning to soil and hindered cycling of carbon and nitrogen again. (4) We explored plant litter removal, double litter addition, root trenching, and combining root trenching and litter removal treatments to examine the effects of above- and belowground carbon inputs on soil microbial biomass, WDOC and WDON in four secondary plantations. During the experimental period from June 2007 to July 2008, 1 year after initiation of the treatments, WDOC in soil did not vary in root trenching, and combining root trenching and litter removal treatments, while WDON in soil significantly increased compared with CK treatment. Root trenching reduced soil MBC and MBN in PT plantation, while MBC and MBN in soil did not vary in LK plantation. The rasults implied that soil microbial activity was more dependent on belowground carbon input in PT plantation than those in other secondary plantations, on the contrary, soil microbial activity in LK plantation was not dependent on belowground carbon input. Plant litter removal significantly decreased soil WDOC in LK plantation, decreased WDON in PA and CJ plantations, and also significantly reduced soil MBC in PT plantation. However, double litter addition did not increase soil microbial biomass, WDOC and WDON, on the contrary, soil WDON in CJ, PA and PT plantations were decreased. These suggested that soil microbial activity was not only dependent on belowground carbon input, but also on aboveground organic material input. Double litter addition could change the microclimate and result in the decrease of soil microbial activity in CJ, PA and PT plantations. (5) We measured carbon mineralization in a 107 days incubation experiment in 5℃,15℃ and 25℃. Carbon cumulative mineralization was positively correlated with organic matter and labile organic carbon in litter layer and soil. Cumulative carbon mineralization and mineralization rate of litter layers in PT and PA plantations were higher than that in native broad-leaf shrub. This difference between native broad-leaf shrub and coniferous plantations in cumulative carbon mineralization and mineralization rate of litter layers could be attributed to the initiating time of decomposition due to the difference in seasonal dynamic of litter fall production between two types of secondary plantations. However, cumulative carbon mineralization and mineralization rate in soil were the highest in native broad-leaf shrub and CJ plantation, and were the lowest in PT and PA plantations. This also confirmed that PT and PA plantations substituting for native broad-leaf shrub hindered the cycling and turnover of organic matter again. (6) Carbon cumulative mineralization was positively correlated with C/N in litter layer and increased with temperature increasing, while carbon cumulative mineralization was not correlated with C/N in soil. This indicated that soil organic matter quality (C/N) was insensitive to temperature. Applying bi-exponential model, we computed the percent of labile and stable carbon in different temperature incubation and found that temperature increasing would accelerate the transform from stable carbon to labile carbon and increase the percentage of labile organic carbon. This illuminated that temperature incraesing could facilitate the decomposition of litter and soil organic matter in secondary vegetations and hence affect the relationship between carbon source and sink.

岷江上游人工针叶、阔叶林土壤可溶性有机物质特征及其对凋落物分解的响应

土壤可溶性有机物质（Dissolved organic matter，DOM）作为土壤有机质的活性组分，在陆地生态系统物质循环中扮演非常重要的角色。土壤DOM的主要成分可溶性有机碳（Dissolved organic carbon，DOC）和氮（Dissolved organic nitrogen，DON）参与C、N循环过程。为深入揭示全球C、N循环过程机制，在未开展DOC和DON的地区进行相关研究是有必要的。森林土壤（包括枯枝落叶层）DOC、DON动态及调控机理的研究是目前国际上森林生态系统C、N循环研究热点之一。本研究立足于暖温带岷江上游茂县地区人工林植被，对土壤DOC和DON的库容量，季节动态及其与其它养分之间的关系进行了系统研究，旨在了解DOC和DON在该区生态系统中的重要作用，并探讨作为DOM主要来源的叶凋落物对DOC和DON的动态影响，研究有助于更加详细地了解该区生态系统C和N循环过程。本论文主要研究结论如下： 1研究了岷江上游地区两大主要土壤类型（棕壤和褐土）不同植物群落下土壤的DOC和DON含量及特征，结果表明：DOC和DON在两种土壤类型中均有库容量存在，DOC在0-10cm和10-20cm土层的含量幅度分别111.96~159.95 mg kg-1和69.02~100.84 mg kg-1。DON在0-10cm和10-20cm土层的含量幅度分别11.88~23.08 mg kg-1和4.70~10.77 mg kg-1。游离氨基酸在0-10cm和10-20cm土层的含量幅度分别0.84~1.66 mg kg-1和0.39~0.73 mg kg-1。DOC、DON与土壤中的一些养分因子表现出了显著的相关关系，共同反映了土壤的状况和质量，在该区开展DOC和DON的系统研究是有必要的。 2 对油松与连香树林地土壤DOC、DON以及其它化学指标的季节动态进行了研究，结果表明：油松与连香树林地土壤DOC和DON的季节动态变化表现了类似的规律，DOC和DON的含量均以秋季最高。DOC和DON的季节动态变化主要受凋落物生物因素的影响，但其微生物活力的生物因素以及降雨、温度等非生物因素也是控制土壤DOC和DON含量的重要因素。土壤DON在土壤中的行为不同于矿质氮，其季节动态不同于NO3--N和NH4+-N的季节动态，在研究N循环过程中，应考虑DON的变化情况。 3 对油松与连香树林地分解层和表层土壤（0-10cm）氨基酸周转动态进行了研究，结果表明：油松林地和连香树林地均以分解层的氨基酸含量高于矿质表层土壤的含量。每个取样时期，油松林地内各层次的氨基酸含量高于连香树林地内相应层次的含量。两林地各层次无机氮含量均超过了氨基酸的含量，并且室内培养30天后无机N的含量仍然高于氨基酸的含量，所以可以认为该区立地条件下无论是在有机分解层还是矿质土层植物吸收利用的氮素仍是以无机N为主。 4 松林下松针凋落物易于累积，这与松针凋落物分解缓慢有关，从而导致松林内养分周转缓慢。通过用不同性质凋落物和灌丛地土壤构建微生态系统，比较油松、辐射松、连香树、灌丛虎榛子凋落物分解对C、N循环过程的影响，结果显示油松和辐射松针叶凋落物比连香树、虎榛子凋落物分解更慢，减缓了养分循环过程。然而将针叶凋落物与阔叶凋落物混合后，油松和辐射松针叶凋落物的分解加快，C、N元素的循环过程也加速。此结果表明在松林内维持具有高质量凋落物的灌丛植被或在松林内栽植一些阔叶树种如连香树对维持和增进松树人工林的土壤肥力有重大的作用。室内培养的结果还显示添加凋落物后土壤DOC和DON的含量显著增加，表明凋落物是土壤DOM的直接来源。然而不同物种凋落物处理下土壤DOC和DON的含量有所不同，并随时间发生改变。混合凋落物处理下土壤DOC和DON的含量均高于松针凋落物单独处理下土壤DOC和DON的含量。DON是一个主要的水溶性N库，随时间的变化趋势与无机N的变化趋势不同，在土壤N循环过程中起到了中间N库的作用。 As a labile fraction of soil organic matter, dissolved organic matter (DOM) plays a very important role in material cycling of terrestrial ecosystem. The turnover of DOM is now being considered as main components in nutrient cycling. DOM mainly includes dissolved organic carbon (DOC), -nitrogen (DON), -phosphorous (DOP) and –sulfur (DOS). Among these constituents, DOC and DON directly participate in C and N cycling. It is essential to study DOC and DON dynamics and their controlling factors in the areas where no related study has ever been carried out. Study about them can provide data supports on understanding the mechanism of the global C and N cycling. DOC and DON dynamics and their controlling factors have been focused on in the research of C and N cycling of forest ecosystems. Based on forest plantations of Maoxian, Minjiang River in warm temperate zone, soil DOC and DON pool size, their seasonal dynamics, and the correlation between DOC, DON and other nutrients were studied in order to understand the importance of DOC and DON in the study area. Soil DOC and DON dynamics induced by leaf litter decomposition were also studied. The study contributed to comprehensively understanding C and N cycling processes and providing baseline data for including DOC and DON into the indices system of evaluating nutrient conditions. The results were as follows: 1 Several different plant communities under brown soil and Cinnamon soil were chosen as sampling plots. The contents and features of soil DOC and DON were evaluated. The results showed that DOC and DON were present under the two soil types. DOC contents in the top soil (0-10 cm) and the subsoil (10-20 cm) respectively varied from 111.96 mg kg-1to 159.95 mg kg-1, and 69.02 mg kg-1 to 100.84 mg kg-1. DON contents in the top soil (0-10 cm) and the subsoil (10-20 cm) respectively varied from 11.88 mg kg-1to 23.08 mg kg-1, and 4.70 mg kg-1 to 10.77 mg kg-1. Free amino acid contents in the top soil (0-10 cm) and the subsoil (10-20 cm) respectively varied from 0.84 mg kg-1to 1.66 mg kg-1, and 0.39 mg kg-1 to 0.73 mg kg-1. Significant correlations were found between DOC, DON and some nutrient indices, which together reflected soil condition and quality. It was hence essential to study DOC and DON in the study area. 2 Seasonal dynamics of DOC, DON, inorganic N, microbial biomass C and N were studied under Pinus tabulaeformis and Cercidiphyllum japonicum plantation. The results indicated that seasonal dynamics of soil DOC and DON under the two plantations performed similar change pattern, with the highest values in autumn. The seasonal dynamics of soil DOC and DON were mainly influenced by the litterfall. However, biotic factors such as soil microbial activities and abiotic factors such as precipitation and temperature also controlled the dynamics of soil DOC and DON. The seasonal dynamic of DON was different from that of NO3--N and NH4+-N, which showed that the behavioral differences between DON and inorganic nitrogen. And hence, it was proposed to include DON into soil N cycling in the study area. 3 Amino acid dynamics in Oa and topsoil (0-10 cm) under P. tabulaeformis and C. japonicum plantation were studied. The results showed that amino acid content in Oa was significantly higher than that in mineral soil. At each sampling time, significantly higher amino acid contents were found in P. tabulaeformis plantation than in C. japonicum plantation. The content of inorganic nitrogen was much higher than the content of amino acid in each sampling layer at each sampling time. After a 30-days laboratory incubation the content of amino acid was still lower than the content of inorganic nitrogen. The results implicated that the form of N absorbed by plants in these study sites were mainly inorganic nitrogen. 4 Usually needle litter is more resistant to decomposition, which leads to needle litter accumulation in pure coniferous stands and slows down the rate of nutrient circulation. By constructing microcosms with local shrubland soil and containing the four single-species (P. tabulaeformis, P. radiata, C. japonicum, Ostryopsis davidiana) litters, the decomposition rates and related C and N dynamics of needle litters and broadleaved litters during the early stage were compared. The results showed that the decomposition rates of pine needles were lower than those of broadleaved litters, which descended C and N cycling processes. However, the presence of C. japonicum or O. davidiana litter into pine needles increased the decomposition rates of pine needles and also dramatically promoted C and N cycling processes. It should be appropriate for plantation managers to consider C. japonicum as an ameliorative species or remain O. davidiana in pine plantations to improve soil conditions and help maintain soil fertility. The laboratory incubation still showed that DOC and DON contents in all litter-amended treatments were significantly higher than no litter-amended treatment, which proved that litter could be a direct source of DOM in soils. Different species litters induced different soil DOC and DON contents, which correspondingly changed over time. DOC and DON contents in mixed litter treatments were higher than those in pine needle litter treatments. As a major soluble N pool, DON developed a different changing pattern over time compared with inorganic N and played a role of interim N pool in soil N cycling.

岷江上游高山林线附近优势树种土壤种子库和幼苗更新特征的研究

岷江上游地区高山/亚高山植被分布的坡向性分异显著，阴阳坡高山林线不仅物种组成差异明显，并且分布海拔呈现出阴坡高阳坡低的格局．阳坡林线树种主要是圆柏属乔木，林线类型多为渐变型，海拔高度大约在3 400m~3 800m；阴坡林线树种主要是冷杉，林线类型多为骤变型，海拔高度约在3 800m~4 400m．本研究采用土壤种子库物理筛选、室内萌发实验及野外群落调查等方法，对岷江上游地区阴坡岷江冷杉和阳坡祁连圆柏两类林线树种不同海拔梯度上土壤种子库以及幼苗库特征进行了调查，从土壤种子库和幼苗更新特征的角度对林线乔木树种种群更新特征进行了分析，进而对该地区高山林线在阴阳坡分布差异的原因进行了探讨，结果显示： 1．土壤种子库 阴坡：阴坡高山林线附近岷江冷杉土壤种子的平均密度大约为50.96粒/m2，其中树线以上10m处土壤种子密度为1.00粒/m2，树线处大约19.33粒/m2，林线交错带内土壤种子密度最高为136.83粒/m2，郁闭林内种子密度小于林线交错带，只有30.50粒/m2，种子平均空壳率为52％，霉变率达34%，完好种子只有6%．土壤种子库垂直分布特征为地被物层含种子比重最大，大约在67.50%左右；其次为0~2cm层，约18.84%左右；2~5cm层所占种子比例最小，约13.66%左右．霉变种子数量与土壤深度呈负相关． 阳坡：阳坡祁连圆柏土壤种子的平均密度为60.16粒/m2．树线以上10m处密度为1.92粒/m2，树线位置大约108.16粒/m2，林线交错带内平均为75.80粒/m2，郁闭林内种子密度小于林线交错带，只有20.00粒/m2．种子平均空壳率为36％，完好种子占49%，霉变率较低，大约为10%．阴阳坡林线树种土壤种子库垂直分布特征为：地被物层含种子最多，其次为0~4cm层，4~10cm层所占种子比例最小，霉变种子数量与土壤深度也呈负相关． 2． 幼苗库调查 阳坡：在树线以上区域没有发现幼苗，林线交错带内幼苗密度平均达3 250株/hm2，郁闭林内仅2 750株/ hm2．整个样地内1～2a幼苗很少甚至没有出现，3～10a的幼苗相对较多．空间分布上，祁连圆柏幼苗在林线交错带内接近随机分布，郁闭林内则介于随机分布和均匀分布之间． 阴坡：在树线以上幼苗密度为1 250株/ hm2，全部为1~2a幼苗，林线交错带内幼苗密度平均达7 000株/ hm2，郁闭林内达6 250株/ hm2．林线附近岷江冷杉幼苗丰富度以及幼苗的出现频率明显高于祁连圆柏，年龄结构也较祁连圆柏完整．岷江冷杉幼苗空间分布除了树线处幼苗的分布为随机分布，其他海拔则为集群分布． 3．从不同土壤深度的种子总量和幼苗数量的相关性检验发现，当年生幼苗数量跟表层种子总量相关性极显著, 但是两年生幼苗的数量与底层种子数量相关性显著．土壤种子在土壤中的垂直分布格局从一定程度上可以反映种子库的年际特征．岷江冷杉土壤种子库较丰富，种子散布后的存活力随着时间的变化逐渐下降，属于季节性瞬时种子库；祁连圆柏土壤种子散布格局为集群型分布，成熟种子大部分散布在母株冠幅内，属于永久性土壤种子库． 4．在阴坡林线交错带及以上区域还存在较为丰富的乔木土壤种子，并且在树线以上区域还发现了少量的岷江冷杉幼苗．从样地乔木的年龄结构发现，在林线交错带内上部到树线位置主要以幼龄林为主，且年龄结构完整，基本符合入侵性林线特征；阳坡林线交错带内幼苗出现频率很低，树线以上区域虽然存在种子库，但是没有幼苗出现，在林线交错带内乔木径级差距很大，年龄结构异常不完整，这种特征的林线将会面临两个可能结果：一种是维持现有状态，保持平衡；另外一种就是退化，但阳坡林线的实际动态趋势还有待长期定点研究． Treelines on the upper region of Minjiang River differ between the north aspect and the south aspect in their appearances, altitudes and tree species. On the north aspect, trees of Abies form a sharp and abrupt treeline ranging from 3800m to 4400m, while on the south the treeline is generally lower(3 400~3 800m), more open and gradual and mostly composed of Sabina. In this study, we examined the altitudinal gradients of soil seed banks and seedling recruitments at the treeline ecotones of a N-aspect and a S-aspect by using soil sieving, germination experiment and field investigations, analyzed the characteristics of population regeneration of tree species at the transitional zone and presented a analysis of the causes to the aspect-related difference in treeline patterns in the study area. Major results of our study include: 1． Soil seed bank N-aspect: Of the 50 plots investigated, the average density of soil seeds is 50.96/m2, in which well-formed seeds account for 6%, empty seeds 52%, parasitized seeds34%, and seeds damaged by animals 8%. The size of soil seed bank varies along altitude, being 1.00 seeds /m2 at the 10m above the treeline and ca.19.33 seeds/m2 at the upper limit of treeline. The highest density (136.83 seeds/m2) occurs at the treeline ecotone. By contrast, the density of soil seed for the closed forest is only 30.50 seeds/m2. In terms of vertical strata, 67.50% of the total seeds are at the surface layer, 18.84% at the middle layer (0~2cm) and 13.66% at deeper layer (2~5cm). The number of parasitized seeds is negatively correlated to soil depth. S-aspect: Of the 50 plots investigated, the average density of soil seeds is 60.16 seeds/m2, and the well-formed seeds account for 49%, empty seeds 36%, parasitized seeds10%, and seeds damaged by animals 1%. The size of soil seed bank varies along altitude, with 1.92 seeds/m2 recorded at the10m above the treeline，108.16 seeds/m2 at the upper limit of treeline, and 75.80 seeds/m2 at the treeline ecotone, while that for the closed forest is 20.00 seeds/m2. The number of seeds decreases with the depth of soil. As is on the N-aspect, the size of soil bank, from large to small, follows the order of the surface layer, the middle layer (0~4cm) and the bottom layer (4~10cm). The number of parasitized seeds is also negatively correlated to the depth of the soil. 2． Seedling bank N-aspect: A mean maximum seedling abundance of 31 000 seedlings/hm2 was recorded near alpine treeline at growing season. The density of seedlings is 1 250 seedlings/ha (all being 1 or 2 years old) at the alpine meadow 10m away above treeline, 7 000 seedlings/ha at treeline ecotone and 6 250 seedlings/ha for closed forest．The spatial distribution of Abies faxoniana seedlings is random at the upper limit of the treeline but clumped at other altitudes． S-aspect: No seedlings were found at the alpine meadow 10m away from the treeline. The density of seedlings was 3 250 seedlings/ha at treeline ecotone and 2 750 seedlings/ha for the closed forest．Hardly any 1 year current and 2 year-old seedlings appeared at the plots. The spatial distribution of Sabina przewalskii seedlings is random at treeline ecotone and between “random” and “even” forest closed forest． 3．Correlation tests of seedling population and seed bank at different soil layers indicated that the emergents were strongly correlated to seed bank at surface layer while the number of two-year seedlings was significantly correlated to the seed bank at the bottom of soil layer, indicating that germination mainly occurs at the soil surface while the middle or bottom layer was the reserve for non-germination or dead seeds. It can thus be postulated that Abies faxoniana soil seed bank is of seasonal transient type. By contrast, the soil seed bank of Sabina przewalskii is of persistent type and the soil seeds and seedlings of this species occurred more frequently near the islands of adult trees. 4．A good many soil seeds of both tree species were found near the treeline ecotone and above at N- and S-aspects. A few young seedlings were found above the Abies treeline. Investigation of five altitudinal transects respectively on N- and S-aspects indicated that Abies faxoniana has a more complete age structure than the stands of Sabina przewalskii. The age of firs decreased from closed forest to the upper limit of treeline, which suggests that the Abies treeline is advancing to higher altitude. While on the south aspect, only few Sabina przewalskii soil seeds and nearly no seedlings were found above the treeline ecotone. The stands exhibit extremely great difference in diameter classes with significantly incomplete age structure. This would lead to two possible results for the treelines: maintaining an equilibrium state at the current position or degenerating. But more studies should be carried out at longer time scales or larger spatial scales to understand whether the Sabina treeline is degenerating.

次生植被下土壤活性有机碳组分季节动态研究

为了揭示不同类型植被下土壤有机碳及其活性组分季节动态变化及其特点，探讨不同的植被恢复模式对土壤有机碳组分的影响，分析影响土壤有机碳组分变化的因素，评估土壤有机活性有机碳组分参数在植被恢复过程中土壤质量监测的可靠性，为植被恢复及低效林改造技术提供理论依据。本研究选择岷江上游大沟流域的几种人工林（云杉林、油松林、华山松林、日本落叶松林）以及次生落叶阔叶灌丛下土壤，通过剖面机械分层取样，测定土壤总有机碳（TOC）和三种活性碳组分微生物碳（SMBC）、水溶性碳（WSOC）、易氧化碳（EOC）等来反映土壤变化特点。主要结果是： 1. 土壤有机碳含量平均在15.48~25.46 g kg-1之间在5月份时含量最低，随生长季的开始，有机碳含量逐渐增加，到9月份时含量达到最大值；由于新形成的凋落物不能被迅速分解利用补充土壤碳库，而原有碳库经历一个生长季的分解利用，因此，生长季末期即11月份的含量较小；土壤微生物碳含量平均在132.78~476.73mg kg-1之间，9月份和11月份含量都比较高；水溶性碳在生长季中逐步增大，含量在51.95~77.18 mg kg-1之间，到11月份时达到最大值；土壤易氧化碳平均含量在3.74~5.79g kg-1之间，含量最低值出现在5月份，但和其他碳组分不同的是其在7月份时含量较高。 2. 土壤有机碳及其活性碳组分大小关系为：TOC>EOC >SMBC>WSOC；比值约为300：70：5：1。 3. 土壤不同层次间比较，土壤碳指标都表现为随土壤深度增加而逐渐减小, 表层积聚作用明显。 4. 对土壤总有机碳量与活性碳组分以及活性碳之间进行了相关分析表明，土壤总有机碳含量与土壤微生物量碳、水溶性碳、易氧化碳之间的相关性均达到显著水平（P<0.05），有机碳总贮量很大程度上制约着土壤活性碳组分。土壤微生物量碳、水溶性碳、易氧化碳两两之间也都存在着显著相关关系（P<0.05），并随着不同植被类型或立地条件因子发生变化而变化。 5. 土壤有机碳及其活性组分与土壤养分状况之间的相关性分析发现，随着海拔、坡向或者植被类型的改变，其林下土壤有机碳及其活性组分与土壤养分的相关性也发生较大的变化。总体而言，岷江上游地区海拔、坡向、土壤自然含水量、植被盖度、凋落物厚度、土壤全N对次生林下土壤有机碳及其组分有重要影响。而AP、AK、C/N对土壤碳变化变化影响较小。 6. 通过不同海拔、坡向以及植被类型之间的综合比较分析发现，土壤微生物碳SMBC和水溶性碳WSOC比TOC和EOC更能敏感地反映出比较敏感的指示林下土壤质量的变化。 In order to reveal seasonal dynamics of soil labile organic carbon under different secondary vegetation, to analyze effect of different vegetation restoration pattern on soil organic carbon and its fractions, and to find the factors influencing changes in soil organic carbon and its fractions, further to estimate those parameters reliability for soil quality monitoring in the process of vegetation restoration. Soils were selected from several plantations, including Picea asperata Pinus tabulaeformis, Pinus armandii and Larix kaempferi and secondary shrub in Dagou Watershed of the upper reach of Minjiang River. The measurement of TOC, SMBC，WSOC and EOC were made, because these parameters can reflect change of soil characteristics. The major results are: 1. There were the lowest soil organic carbon and its labile fractions contents in May. At the time of growth initiation, they increased gradually and reached maximum in September. After that the soil organic carbon content decreased. Because current litter couldn’t be rapidly decomposed, and supplemented into carbon pool, while intrinsic carbon pool experienced decomposition and utilization of growth season, Which led a decrease in soil organic carbon content in November. Average value was 15.48~25.46 g kg-1; average SMBC content was 132.78~476.73mg kg-1.There were higher SMBC content in September and November as compared with other times; Water soluble organic carbon content increased from 51.95 mg kg-1 in May to 77.18 mg kg-1 in November; EOC content was lowest in May y. Average value was 3.74~5.79g kg-1. Differeing from other parameters of carbon fractions, EOC content was higher in July. 2. The content of soil organic carbon and its labile carbon fractions ranked as follows：TOC>EOC >SMBC>WSO，and ratio was about 300：70：5：1. 3. Consider as soil different layers，all of the parameters decreased gradually with increasing soil depth, thus displayed a significant accumulation in the surface layer soil. 4. Correlations coefficient analysis revealed that, TOC significantly correlated with SMBC, WSOC and EOC indicating total storage of organic carbon limited soil labile carbon fractions in great extent. On the other hand, there were significant correlations between SMBC，WSOC and EOC. But these relationships changed with vegetation types and/or environmental conditions. 5. The relationships between soil organic carbon and its labile fractions and soil nutrient traits changed with altitude，slope aspect and vegetations. Therefore our results suggested that altitude，slope aspect，soil natural water content，vegetation coverage, litter thickness and soil total nitrogen play a important role change in soil organic carbon and its fractions in upper reaches of Minjiang River. While AP、AK、C/N slightly influenced soil carbon. 6. Our results, on the other hand suggested that SMBC and WSOC are more sensitive to the change of altitudes, slope aspects, vegetation types than TOC and EOC, thus two parameters may be good index reflecting change of soil quality. These results provide insights into theoretical and technological evidences for the vegetation regeneration restoration and improvement of low-quality and benefit forest in the upper reaches of Minjiang River regions.