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.

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.

九寨沟景区旅游活动扰动形成的退化地段植被恢复试验初报

日益增强的旅游活动干扰已成为九寨沟世界自然遗产的有效保护与持续管理不可回避的问题，也已成为当前区域生态保护与经济发展的焦点问题之一。评估乡土植物种的基本特征、质量、种子休眠程度以及萌发能力；筛选适宜的植被恢复乡土物种并选择有效植被恢复技术措施是开展植被恢复试验的重要前提和保障。本文以九寨沟世界自然遗产为例,通过对景区乡土植物种子基本特征的测定以及采用乡土物种作为植被恢复技术试验与恢复技术筛选的试验物种，在景区旅游干扰区的三种生境类型：原始针叶林、混交林和边坡，根据不同的影响因素设计试验，从而探索适宜的恢复措施和植被恢复物种。初步结论如下： 1． 本文研究的28种乡土植物中，17种测定的物种活力较高(>72%)，均具有作为恢复物种的潜力。但28种种子中75%的发芽率为0%。大部分种子存在一定程度的休眠，包括甘肃山楂、称花藤、疏花槭、陇东海棠、球花荚迷、巴东小檗、蔷薇、宝兴栒子、光泽栒子、光枝柳叶忍冬、甘青铁线莲、毛果铁线莲、宽叶旌节花、糙叶五加和独活。因而种子存在深度休眠是乡土物种自然更新和植被恢复的主要障碍，需要根据种子的形态生理特征，寻求打破乡土植物种子休眠的有效方法，提高种子发芽率。 2．低温层积只显著提高了蔷薇、毛果铁线莲、宽叶旌节花和假升麻3种种子的发芽率，也相对较早地提高了陇东海棠、鲜黄小檗和独活的萌发。对于其它物种的种子，低温层积没能有效打破休眠提高发芽率。综合分析结果表明九寨沟28种林下或林缘乡土植物中窄叶鲜卑花、毛果铁线莲、宽叶旌节花、假升麻、陇东海棠、鲜黄小檗和独活等12种可直播或通过低温层积处理后直播用于旅游干扰退化地段的植被恢复中，而其它的种类尚需进一步寻求打破休眠的措施以提高种子发芽能力。 3．在原始林生境下，七筋菇、巴东小檗、耳叶风毛菊、长叶毛花忍冬及独活5种乡土植物种子的出苗能力不高，因此目前急需提出有关提高种子出苗的方法措施。在相同的处理条件下，不同物种出苗数存在着较大的差异，相比而言，巴东小檗、耳叶风毛菊和长叶毛花忍冬种子出苗与幼苗存活较高，对于其环境适应能力较强，因此它们更适宜采用播种的方式应用于九寨沟原始林践踏地段地表的植被恢复实践；而七筋菇和独活在室内和自然气候条件下萌发都很困难，在植被恢复过程中，可考虑采用其它播种方式。而在边坡和混交林生境试验结果表明，供试物种无萌发和出苗现象，这可能跟外界环境条件、干扰和种子命运有关。 4． 本研究中腐殖质、松土和苔藓覆盖处理措施均未能提高物种出苗，且对样方内植被结构以及物种丰富度也无显著影响，其中的影响因素也是多方面的，因此还需进一步研究探索。但腐殖质对幼苗存活能力方面有一定的积极作用。 The increasing tourism disturbance is an unavoidable issue to effective conservation and sustaind tourist management of Jiuzhaigou Nature Reserve. It has become one of the focal problems of regional ecological protect and economic development. Assessing the traits, quality, seed dormancy and germination of native seed and choosing the suitable species and ways for vegetation restoration were the important precondition and guarantee before vegetation restoration. In this paper, as an example to Jiuzhaigou world nature heritage, through the estimation to the basic characteristics of native seeds and the use of native species for the test of vegetation restoration and the choosing of vegetation restoration techniques, in three different habitats being disturbed, including the primitive forest, mixed forest and side slope. According to different factors, designing experiments in order to explore the appropriate measures and species of vegetation restoration . Our results are as follows: 1． There are 77% seeds of the 28 species with high viability(>72%), which had the potential possibility of being restoration species. The germination of 75% of the seed was 0%.Most of the seed was dormant, So dormancy of seed was the barrier for natural regeneration and vegetation restoration, Further research is needed on investigating the other more effective methods to release seed dormancy of these native species in the future. 2． Cold stratification did not release seed dormancy of most species. In our study, there are only 3 species including Clematis peterae var. trichocarpa, Stachyurus chinensis and Aruncus sylvester (P<0.05) with germination percentage increased by cold stratification. By comprehensive analysis, the result shows: In 28 undergrowth native seeds, Sibiraea angustata, Clematis peterae var. trichocarpa, Stachyurus chinensis, Aruncus Sylvester, Malus kansuensis, Berberis diaphana,and Heracleum hemsleyanum could be used to vegetation restoration by sowing directly or sowing after cold stratification in degenerate gland being disturbed by turism, and othes seed of 28 were needed to search other methods to release seed dormancy for advancing the ability of germination. 3．In the habitat of primitive forest, the ability of emergence of the native species Clintonia udensis, Berberis henryana, Saussurea neofranchetii, Lonicera trichosantha var.xerocalyx and Heracleum hemsleyanum was low, so it is urgently needed to search about the methods of advancing emergence. In the sametreatment, the number of emergence of different species was very different. Relatively speaking, the emergence and seedling survival of the species Berberis henryana, Saussurea neofranchetii and Lonicera trichosantha var.xerocalyx was higher, and the adaptability of the species was better, so they were more suitable for vegetation restoration on trampling-induced degraded patches of primitive forest in Jiuzhaigou; But the germination of Clintonia udensis and Heracleum hemsleyanum was both difficult in laboratory and natural conditions, so it could be considered to apply other sowing methods. However, the result showed that: applied species didn’t germinate or emergent in the habitat of side slope and mixed forest, which could be related to external environment conditions, interference and the fate of the seed. 4．In this study, humus, scatification and bryophyte cover measures didn’t advance the emergence of the species or the structure of vegetation and richness in plot significantly, the impact factors of which were many, therefore further research is needed . However, humus had a certain positive effect on the ability of seedling survival.

Adenovirus-mediated wild-type P53 Transfer radiosensitizes H1299 cells to subclinical-dose carbon-ion irradiation through the restoration of p53 function

To determine whether adenovirus-mediated wild-type p53 transfer after radiotherapy could radiosensitize non-small-cell lung cancer (NSCLC) cells to subclinical-dose carbon-ion beam (C-beam), H1299 cells were exposed to a C-beam or -ray and then infected with 5 MOI of AdCMV-p53 or GFP (C-beam or -ray with p53 or GFP).Cell cycle was detected by flow cytometric analysis. The apoptosis was examined by a fluorescent microscope with DAPI staining. DNA fragmentation was monitored by the TUNEL assay. P53 mRNA was detected by reverse-transcriptase polymerase chain reaction. The expression of p53, MDM2, and p21 was monitored by Western blot. Survival fractions were determined by colony-forming assay. The percentages of G1-phase cells in C-beam with p53 increased by 8.2%–16.0%, 5.2%–7.0%, and 5.8%–18.9%, respectively, compared with C-beam only, -ray with p53, or p53 only. The accumulation of G2-phase cells in C-beam with p53 increased by 5.7%–8.9% and 8.8%–14.8%, compared with those in -ray with p53 or p53 only, respectively. The percentage of apoptosis for C-beam with p53 increased by 7.4%–19.1%, 5.8%–11.7%, and 5.2%–19.2%, respectively, compared with C-beam only, -ray with p53, or p53 only. The level of p53 mRNA in C-beam with p53 was significantly higher than that in p53 only. The expression level of p53 and p21 in C-beam with p53 was significantly higher than that in both C-beam with GFP and p53 only. The survival fractions for C-beam with p53 were significantly less than those for the other groups (p 0.05). The data suggested that AdCMV-p53 transfer could more efficiently radiosensitize H1299 cells to subclinical-dose C-beam irradiation through the restoration of p53 function.

Did an extensive forest ever develop on the Chinese Loess Plateau during the past 130 ka?: a test using soil carbon isotopic signatures

IEECAS SKLLQG

Restoration of the signals from multi-hit three-layer delay-line anode position-sensitive detector

Multi-hit 3-layer delay-line anode (Hexanode) has an increased ability to detect multi-hit events in a collision experiment. Coupled with a pair of micro-channel plates, it can provide position information of the particles even if the particles arrive at the same time or within small time dwell. But it suffers from some ambiguous outputs and signal losses due to timing order and triggering thresholds etc. We have developed a signal reconstruction program to correct those events. After the program correction, the dead time only exists when 2 paxticles arrive at the same time and the same position within a much smaller range. With the combination of Hexanode and the program, the experimental efficiencies will be greatly improved in near threshold double ionization on He collisions.

辽西低山丘陵区生态系统退化程度的定量确定

Exactly measuring the degradation degree of ecosystems is the basis and precondition of restoring ecosystems. At present,degradation degree is usually analyzed qualitatively.In this paper,quantitative classification method was used to study the degradation degree of ecosystem in hilly region of western Liaoning,which was measured by the degradation degree of habitat.The result shows that the habitat in the northern slope of mountains has been degraded to certain stage between shrubbery and pioneer tree forest,which provides theoretical basis for vegetation restoration practice. Moreover,the result is beneficial for studying the degradation degree of ecosystems in other regions or of other types.

黄土丘陵区退耕地植被景观时空变异特征

对黄土丘陵区退耕地植被特征的时空变异性进行了研究。结果表明,不同植被类型区植被特征之间差异不是很显著,仅延安与安塞在物种丰富度之间和安塞与吴旗在物种多样性之间存在较显著的差异(0.01

黄土高原生物气候分区与该区生态系统的恢复

根据不同的生物气候状况 ,可将黄土高原分成五个生物气候区 :暖温带湿润半湿润森林区、暖温带半湿润半干旱森林草原区、中温带半干旱典型草原区、中温带干旱半干旱荒漠草原区以及中温带干旱草原化荒漠区。紧密结合上述生物气候区域特征 ,将生态学的有关原理引入到该区的治理与生态恢复中 ,提出了治理黄土高原的新模式 :正确实施生物措施 ,人工模拟天然生态系统。该区的生态恢复应从系统的角度考虑 ,并严格遵守生态学的有关规律在不同的生物气候区构建与该区大环境一致的不同的生态系统 ,改变过去那种在黄土高原全面造林而又成效不佳的做法

生态恢复后的千烟洲植物群落种类组成及结构特征

Qianyanzhou(QYZ) Ecological Station established in 1983 with an area of 204 hm~2 is affiliated to the Chinese Ecosystem Research Network.Before 1982,herbs had been dominant,sparsely dotted with shrubs.After 20-year restoration of the vegetation,the vegetation showed significant changes in both forest coverage and species diversity.Forest coverage had increased to 93.3% in 1999 from 0.4% in 1982.The vegetation could be broadly classified into two groups: artificial forest,accounting for the most percent,and natural secondary forest.These two groups could be subdivided into 12 types.Based on the 2003 field work,The authors studied plant community composition and vertical structure.The results were as follows: 1) On the study plots were there about 150 species,of which 100,49,and 47 grew in arbor layer and shrub layer and herb layer,respectively.Of 12 community types,the amount of species in shrub layer was larger than that of other two layers.As to the species richness in the different community types,Liquidambar formosana community showed the highest and Imperata cylindrical var.major community the least.The amount of species in arbor layer of artificial forest was smaller than those of natural Pinus massoniana forest,but no difference in understory.2) Loropetalum chinense,Quercus fabric and Vaccinium bracteatum were dominant shrub species with a wide distribution.Three ferns Woodwardia japonica、Dryopteris atrata and Dicrannepteris dichotoma were dominant herb species.Lianas were sparse,but Milletlia reticulata were found in all forest types.3) Up to now some natural regeneration species,such as Eurya muricata、Quercus fabri、Vaccinium bracteatum、Rhus chinensis、Adinandra bockiana,had grown in the arbor layer of artificial forests.Some herb species,such as Arundinella setosa、Miscanthus floridulus、Isachne globosa、Scirpus triqueter,which were dominant ones in the herb layer before the restoration of vegetation,disappeared now.4) The vertical structure of natural Pinus massoniana community and Liquidambar formosana community showed more complex comparing with artificial forests.For the artificial forests,the conifer and broad-leaves mixed forest had a more complex structure.In both natural Pinus(massoniana) community and Liquidambar formosana community,it was dominated by individuals with height of 3～4 m,while 10～12 m in the artificial forests.