黄土高原地区主要植被类型的气候梯度分布

应用Thronthwaite的方法,对黄土高原286个气象站(台)的某些气候指标进行了计算,其中包括校正的潜在蒸散(APE)、水分指数(IM)、热量系数(TE)、干旱指数(IA)和湿润指数(IH)。同时,得到了每项气候指标的地理回归模型,并利用各项地理回归模型分别做出了各项气候指标的地区分布图。APE和IM与黄土高原地区植被的主要类型及其分布格局有密切的关系。本区大多数的植被类型的IM均为负值,照例划入干旱亚湿润-半干旱-干旱(dry subhumid-semiarid-arid)地区内,而大部分植被的TE在57.1—85.5之间,应属中温范畴。植被与气候指标的相关性表明:黄土高原南端的地带性植被,实际上为干旱森林、疏林和灌丛,它们在性质上与分布于山地上的辽东栋(Quercus liaotungensis Koiz.)林有所区别。     

植被的PE（可能蒸散）指标与植被气候分类（三）

Holdridge的生命地带分类系统由于其指标的计算十分简便与对植被的对应性强而受到国际植被生态学界与环境科学研究者的重视。特别是近年来在环境的评价、生态区划与预测全球变化对生态系统的影响等方面得到较多采用。该系统对中国各植被地带的气候台站资料进行计算分析的结果表明有较好的适应性。但由于该系统发展于中美洲的热带地区,因而在中国的亚热带地区须进行局部的调整。但采用该系统将有利于与世界各地的气候—植被分类系统的统一与对比研究。通过回归计算表明,该系统的可能蒸散率(PER)指标与CHIKUGO模型的辐射干燥度(RDI)显著相关。因而可以采用便于取得资料与易于计算的PER来进行潜在第一性生产力(NPP)的估算。对中国各植被地带的计算结果令人满意,可进一步用于在全球变化条件下,中国各植被地带或生态系统主要类型及其NPP变化的预测。     

植被气候关系与我国的植被分区

气候制约着植被的地理分布,植被是区域气候特征的反映和指示,两者之间存在密不可分的联系.揭示植被与气候之间的关系是正确认识植被分布的前提,是进行植被区划的理论基础.植被区划是植被研究的归纳和总结,是其他自然地理区划和农林业区划的基础.本文在简要回顾中国植被气候关系及植被分区的研究历史的基础上,对我国以往的主要植被分区原则、依据和方案进行了评述,对有争议的主要植被界线进行了讨论.我们认为,在当今我国大部分地区的原生植被已遭到破坏的现实情况下,根据原生植被及其衍生植被类型的分布,确定其分布与限制性气候因子的关系,以此来进行植被带(区)的划分,不仅反映植被气候间密不可分的关系,在实践上也便于操作.尽管在一些植被带的命名、具体界线的划定上有分歧,但最近的中国植被分区方案大都认为我国基本的植被区有8至9个,即针叶林、针阔叶混交林、落叶阔叶林、常绿落叶阔叶混交林、常绿阔叶林以及雨林季雨林、草原、荒漠以及高寒植被.通过分析主要植被带附近的植被、气候等特征,本文认为,1)秦岭淮河线是一条重要的水分气候带,而不是温度带,不是亚热带植被的北界;2)我国亚热带植被的北界基本上沿长江北岸,从杭州湾经太湖、安徽宣城、铜陵经大别山南坡到武汉往西,与WI值130-140 ℃·月一致;3)我国热带区域的面积极小,仅分布在海南岛的东南部和台湾南端及其以南地区; 4) 我国东部地区暖温带的水热条件南北差异甚大,建议以秦岭淮河为界,将暖温带划分为两个植被带,即落叶阔叶疏林带和落叶常绿阔叶混交林带;华北地区的地带性植被为落叶阔叶疏林.最后,本文还强调了对应于气候变化进行动态植被分区的重要性.     

植被的PE(可能蒸散)指标与植被-气候分类(一)——几种主要方法与PEP程序介绍

植物群落学研究的任务之一是关于群落的环境解释。植被-气候的相关定量分析是其中主要的一环。可能蒸散(PE)作为综合热量与水分两个最重要的生态因子的参数与联系植物及其环境的数量指标而引起了植物生态学家、地理学家与气候学家的重视。本文分篇介绍几种最重要与较成功的PE计算方法及植被—气候分类,并提供其微机计算与分类程序(PEP)以便使用,并期望促进这方面的研究。介绍的方法有：Penman,Thornthwaite,Holdridge与Kira(吉良竜夫)的公式或计算法。     

植被气候关系与我国的植被分区(英文)

气候制约着植被的地理分布 ,植被是区域气候特征的反映和指示 ,两者之间存在密不可分的联系。揭示植被与气候之间的关系是正确认识植被分布的前提 ,是进行植被区划的理论基础。植被区划是植被研究的归纳和总结 ,是其他自然地理区划和农林业区划的基础。本文在简要回顾中国植被气候关系及植被分区的研究历史的基础上 ,对我国以往的主要植被分区原则、依据和方案进行了评述 ,对有争议的主要植被界线进行了讨论。我们认为 ,在当今我国大部分地区的原生植被已遭到破坏的现实情况下 ,根据原生植被及其衍生植被类型的分布 ,确定其分布与限制性气候因子的关系 ,以此来进行植被带 (区 )的划分 ,不仅反映植被气候间密不可分的关系 ,在实践上也便于操作。尽管在一些植被带的命名、具体界线的划定上有分歧 ,但最近的中国植被分区方案大都认为我国基本的植被区有 8至 9个 ,即针叶林、针阔叶混交林、落叶阔叶林、常绿落叶阔叶混交林、常绿阔叶林以及雨林季雨林、草原、荒漠以及高寒植被。通过分析主要植被带附近的植被、气候等特征 ,本文认为 ,1)秦岭淮河线是一条重要的水分气候带 ,而不是温度带 ,不是亚热带植被的北界 ;2 )我国亚热带植被的北界基本上沿长江北岸 ,从杭州湾经太湖、安徽宣城、铜陵经大别山南坡到武汉     

2001-2019年台风干扰下我国东南沿海地区植被抵抗力和恢复力评估

台风是影响我国陆地生态系统结构和功能的主要自然灾害之一,尤其对东南沿海地区植被具有明显的干扰效应。为深入了解台风对我国沿海地区植被的影响及其响应,基于MODIS增强型植被指数(Enhanced Vegetation Index, EVI)和叶面积指数(Leaf Area Index, LAI),分析了2001-2019年间不同等级的台风对植被EVI和LAI的影响,评估台风登陆时植被的抵抗力及台风过后植被的恢复力。结果表明:(1)2001-2019年间,共有70个台风登陆我国东南沿海地区,其中,台风(TY)、强台风(STY)与超强台风(SuperTY)的数量分别为35、26和9个。我国台湾省的台风登陆次数最多,为26个,其次为广东省(20个);(2)在整个研究区范围内,台风(TY)、强台风(STY)与超强台风(SuperTY) 登陆后的EVI净变化率分别为4.88%、-7.48%、-1.85%,LAI净变化率分别为22.28%、-65.70%、-17.60%;(3)在经历台风干扰后,沿海地区大部分植被可在3个月之内得到恢复,其中浙江省与广东省植被的恢复时间较长,海南省与台湾省植被的恢复时间较短。研究结果对我国沿海地区森林经营管理和生态环境保护具有重要意义。     

上海滩涂植被资源遥感分析

利用2003年8月2日L andsat5-TM多光谱遥感影像,运用遥感处理软件ERDA S Im ag ine 8.6,经几何校正分幅裁剪等图像预处理后,采用监督分类和目视解译相结合对上海市滩涂植被进行解译分析。结合全球定位系统(GPS)样点定位,对分类结果进行全面的野外核实和修正,同时利用地理信息系统(G IS)对解译结果进行数据合成,统计出滩涂各类植被的分布区域及面积等数据。实际调查及其分析统计显示,上海滩涂植物群落总面积为21302.1hm2,主要植被组成为芦苇、海三棱草及互花米草三大群落,滩涂植物群落具有明显的高程梯度分布规律。大尺度的上海市滩涂植被的空间分布现状及其数量调查为上海市滩涂资源的合理规划、生物多样性保护和可持续开发利用提供科学依据。     

中国东北植被生态学研究中的焦点问题

中国东北植被经过半个多世纪的系统研究,但有关植被生态学一些争论性问题尚未统一．本文仅就作者近年来研究工作涉及到的内容和关注的问题,提出一些看法：1)中国东北植被地带性分布规律可用Kira的温暖指数(WI）、寒冷指数(CI）和作者的湿度指数(HI)进行定量解释．2)大兴安岭北部山地,在海拔1400m以上存在冻原植被,是作者于1963年首次发现的我国第三块冻原植被,其WI<15℃·月．3)大小兴安岭植被分界线是我国植被区划中第一级分区界线,其位置在爱辉-果松沟-嫩江以南附近,WI为45℃·月．4)大兴安岭植被地带性分异显著,南段、中段为典型草原地带和森林草原地带,北段为针叶林地带,HI值分别为3．5～5．5、5．5～7．5、>7．5mm／℃·月．大兴安岭东麓阔叶林是森林草原带上的森林植被类型．5)东北东部山地岳桦林是山地植被垂直带谱重要组成部分之一,是山地森林垂直分布林线,WI为20～15℃·月为地带性植被类型,而WI>20℃·月为非地带性植被类型．6)内蒙古浑善达克沙地云杉林是陆地上非常罕见的森林生态系统类型,但这种云杉林究竟是哪一树种组成,在中国植物分类上一直是个争论性问题,作者通过核型分析和同工酶实验进一步证明是一个新种即沙地云杉Picea mongolica(H．Q．Wu)W．D．Xu,cmb．NOV．-Picea meyeri Rehd．et Wils var．mogolica(H．Q．Wu)．     

利用草场健康指数监测典型草原的植被退化

利用表征群落总量、放牧退化的主成份和草场健康指数(Grassland Health Index,GHI)与样方光谱反射率之间的相关性,建立了GHI与可见光、红外光因子的回归模型。应用此模型结合TM卫星遥感数据计算GHI,并与同一TM影像的计算出的NDVI作对比研究。研究发现GHI在反映放牧等人为干扰因素对草原植被的影响效应方面比NDVI有明显的优点。此外,GHI对植被分布格局,特别是斑块结构有更好的显示效果。应用GHI到历史TM数据,对所研究地域的植被覆盖变化、农牧业的变迁模式等进行了定性研究。研究发现,有较长放牧史的过度放牧区的植被类型没有沿牧压梯度的规律性分布,而是呈随机斑块模式分布。     

湖北植被区划（上）

根据不同植被类型的组合,植物区系成分,种属的地理分布,植被与生境因素的关系,以及植被改造、利用方向的一致性等为特征进行植被区划,将湖北区域划分为2个植被地带、5个植被区、17个植被小区,并在各植被区划中分别予以描述和讨论。     

The exposure,sensitivity and vulnerability of natural vegetation in China to climate thermal variability (1901–2013): An indicator-based approach

Vulnerability assessments can be helpful in assessing the impact of climate change on natural ecosystems and are expected to support adaptation and/or mitigation strategies in the 21st century. A challenge when conducting such assessments is the integration of the multi-level properties and processes of ecosystems into an assessment framework. Focusing on the primary stresses of climate thermal variability (at both upper and lower extremes), this study proposes a quantitative indicator system—following the IPCC framework of vulnerability assessment—that assesses the impact of historical climate change, during 1901–2013, on the natural terrestrial vegetation types in China. The final output of the vulnerability assessment was expressed as a composite index, composed of ecosystem exposure, sensitivity and resilience to climate thermal change, and including biological, ecological and spatial traits of vegetation types in the assessment. The exposure to temperature variability was generally higher in January than in July, and higher in non-arborous vegetation types than forests. In contrast, sensitivity was higher for forests, wetlands and alpine tundra regions, especially for small areas and areas with scattered patterns. Original forests—especially those distributed in the north—had lower resilience than other vegetation types. The vulnerability of natural vegetation types in China to the temperature variability of the past century was very low to moderate, with a few exceptions, including tropical mangroves and the semi-arid to arid vegetation types in northwestern China, which had high vulnerability. Vulnerability was stronger in winter than in summer. Our results are generally in accord with the scenario-based projections on the geographical pattern of vegetation vulnerability to climate change, and revealed the difference caused by not considering moisture. The risks for these fragmented and narrow-range ecosystems are highlighted, and the importance of natural resilience is stressed for the assessment of vegetation vulnerability to climate change. Given the inadequate coverage of the natural reserve network in China (after the large investment in recent decades) found in the high-vulnerability vegetation types (with a few exceptions), the assessment of natural resilience of ecosystems could be critical for the optimal design of socio-economic strategies in response to the impacts of future climate change.     

Climate and vegetation in China III water balance and distribution of vegetation

Distributions of 29 vegetation types in China as a function of climatic humidity or aridity were analysed using Thornthwaite's system, by employing meteorological records from 671 stations in China. The annual potential evapotranspiration and the humidity/aridity indices were calculated for every station, and distribution maps of water deficiency, water surplus and moisture index (Im) were constructed. The Im map showed that arid areas (Im<0) occupied about 56% of the country. The effect of the difference in soil water storage capacity on Thornthwaite's indices was examined, and Im values were found to differ little, although some differences were observed in actual annual evapotranspiration, water deficiency and water surplus values. Correlations between Im values and distributions of 29 vegetation types, identified from a vegetation map with a scale of 1/4000000, were investigated. The distributions of desert, steppe, woodland, deciduous forest and evergreen forest corresponded to Im values of below −40, −40–−20, −20-0, 0–60 and over 60, respectively. In addition, climatic factors delimiting the northern distribution of evergreen broadleaf forest were investigated, and it was clarified that the northern limit was restricted by combined hydrothermal conditions, and not by the low temperature in winter.     

美国湿地植物指示指标由来及应用

该文略述美国湿地植物指示指标由来并以俄亥俄州立大学湿地研究园人工实验湿地为例,详细地列出了该人工湿地建成15年后的植物及美国湿地植物指示。这个实例有助于中国的湿地恢复及保育。     

Identification and characterization of mitochondrial abasic (AP)-endonuclease in mammalian cells

Abasic (AP)-endonuclease (APE) is responsible for repair of AP sites, and single-strand DNA breaks with 3′ blocking groups that are generated either spontaneously or during repair of damaged or abnormal bases via the DNA base excision repair (BER) pathway in both nucleus and mitochondria. Mammalian cells express only one nuclear APE, 36 kDa APE1, which is essential for survival. Mammalian mitochondrial (mt) BER enzymes other than mtAPE have been characterized. In order to identify and characterize mtAPE, we purified the APE activity from beef liver mitochondria to near homogeneity, and showed that the mtAPE which has 3-fold higher specific activity relative to APE1 is derived from the latter with deletion of 33 N-terminal residues which contain the nuclear localization signal. The mtAPE-sized product could be generated by incubating ³⁵S-labeled APE1 with crude mitochondrial extract, but not with cytosolic or nuclear extract, suggesting that cleavage of APE1 by a specific mitochondria-associated N-terminal peptidase is a prerequisite for mitochondrial import. The low abundance of mtAPE, particularly in cultured cells might be the reason for its earlier lack of detection by western analysis.     

Ubiquitination of human AP-endonuclease 1 (APE1) enhanced by T233E substitution and by CDK5

Apurinic/apyrimidinic endonuclease-1 (APE1) is a multifunctional DNA repair/gene regulatory protein in mammalian cells, and was recently reported to be phosphorylated at Thr233 by CDK5. We here report that ubiquitination of T233E APE1, a mimicry of phospho-T233 APE1, was markedly increased in multiple cell lines. Expression of CDK5 enhanced monoubiquitination of endogenous APE1. Polyubiquitinated APE1 was decreased when K48R ubiquitin was expressed, suggesting that polyubiquitination was mediated mainly through Lys48 of ubiquitin. The ubiquitination activity of MDM2, consistent in its role for APE1 ubiquitination, was increased for T233E APE1 compared to the wild-type APE1. In mouse embryonic fibroblasts lacking the MDM2 gene, ubiquitination of T233E APE1 was still observed probably because of the decreased degradation activity for monoubiquitinated APE1 and because of backup E3 ligases in the cells. Monoubiquitinated APE1 was present in the nucleus, and analyzing global gene expression profiles with or without induction of a ubiquitin-APE1 fusion gene suggested that monoubiquitination enhanced the gene suppression activity of APE1. These data reveal a delicate balance of ubiquitination and phosphorylation activities that alter the gene regulatory function of APE1.     

Vegetation and climate reconstructions on different time scales in China: a review of Chinese palynological research

This paper reviews vegetation and climate reconstructions for different time scales based on palynological studies in China. It discusses examples of significant developments in palynological research topics within China: (1) Modern pollen—a modern pollen database (East Asia Surface Pollen Database) has been established through the collaboration of Chinese palynologists. Based on these data, modern pollen distributions and their quantitative relationship with vegetation and climate have been thoroughly studied. (2) Pre-Quaternary vegetation and climate dynamics—scientists have mapped pollen and palaeobotanical data from the Palaeogene. The vegetation distributions confirm a north–south zonal pattern during the Palaeogene that changed to an east–west monsoonal pattern during the Miocene and Pliocene. These results provide key evidence for understanding monsoon evolution. (3) Late-Quaternary vegetation—biome reconstructions based on fossil pollen data show spatial and temporal changes in vegetation since the Last Glacial Maximum, permitting a better understanding of climate change across China. (4) Quantitative climate reconstructions—some reconstructions have successfully detected Holocene climate variability thereby providing insights into monsoon history. At present, there are no comprehensive spatial reconstructions. Major possible future developments should focus on: (1) long-term vegetation reconstructions from lakes to study Asian monsoon dynamics at orbital scales; (2) quantitative reconstructions of vegetation and climate change to help stronger integration with palaeoclimate models and dynamic vegetation models; (3) land-cover and land-use change across China over the last 6,000 years to understand human impacts and provide empirical data for climate modellers; and (4) integration of pollen data with vegetation and climate modelling to understand the CO₂-vegetation relationship and climate dynamics.     

川西北甘南云冷杉林的DCA排序、环境解释和地理分布模型的研究

 本文应用DCA排序的方法进行了四川西北部和甘肃南部云冷杉林的梯度分析,建立了植物群落梯度环境解释的数学模型和植物群落地理分布的数学模型。研究结果表明：影响川西北甘南云冷杉林植物群落地理分布的生态梯度中最显著并起主导作用的是温度梯度和水分梯度。在水分梯度上,大致有这样的植被序列,由较湿的藓类和杜鹃冷杉及云杉林,中生性的箭竹冷杉林和云杉林,偏旱的高山栎冷杉林和云杉林;处于恢复中期的桦木林的生境也偏旱,但一般不如高山栎林。冷杉林比云杉林更趋于阴湿的生境。 在温度梯度上,呈现出灌木云杉林—桦木林—落阔冷杉林—高山栎云杉林—箭竹云杉林—箭竹红桦林—高山栎冷杉林—藓类红桦林—藓类云杉林—箭竹冷杉林—藓类云冷杉林—藓类冷杉林—小叶章云杉林—杜鹃冷杉林的排序。基本特征是：川西北和甘南的云杉林的温度需求高于冷杉林。川西北云冷杉林与甘南云冷杉林在DCA排序轴上没有明显的区别。虽然川西北地区云冷杉林的海拔分布高于甘南地区,但是其纬度也低于甘南,故在温度条件上基本一致。在水分梯度上,川西北云冷杉林的湿度要稍大于甘南云冷杉林。利用植物地理分布的数学模型和有关的图、表,详细地分析了植物群落的空间分布,进行了环境解释,并找出了主导的环境因子。     

AP endonuclease and poly(ADP-ribose) polymerase-1 interact with the same base excision repair intermediate

Base excision repair (BER) is a defense system that protects cells from deleterious effects secondary to modified or missing DNA bases. BER is known to involve apurinic/apyrimidinic endonuclease (APE) and DNA polymerase ss (ss-pol) among other enzymes, and recent studies have suggested that poly(ADP-ribose) polymerase-1 (PARP-1) also plays a role by virtue of its binding to BER intermediates. The main role of APE is cleavage of the DNA backbone at abasic sites, and the enzyme also can catalyze 3'- to 5'-exonuclease activity at the cleaved abasic site. Photocross-linking studies with mouse embryonic fibroblast (MEF) cell extracts described here indicated that APE and PARP-1 interact with the same APE-cleaved abasic site BER intermediate. The model BER intermediate used includes a synthetic abasic site sugar, i.e. tetrahydrofuran (THF), in place of the natural deoxyribose. APE cross-linked efficiently with this intermediate, but not with a molecule lacking the 5'-THF phosphate group, and the same property was demonstrated for PARP-1. The addition of purified APE to the MEF extract reduced the amount of PARP-1 cross-linked to the BER intermediate, suggesting that APE can compete with PARP-1. APE and PARP-1 were antagonists of each other in in vitro BER related reactions on this model BER intermediate. These results suggest that PARP-1 and APE can interact with the same BER intermediate and that competition between these two proteins may influence their respective BER related functions.     

Studies on Hot Water-soluble and Dilute Alkali-soluble Polysaccharides from the Fruit Body of Mushroom (Psalliota campestris (Linn) Fr.)

The effect of apple polyphenol extract (APE) on the proliferation and invasion of a rat ascites hepatoma cell line of AH109A was examined in vitro. APE suppressed both the hepatoma proliferation and invasion in a dose-dependent manner up to 200 μg/ml. Serum obtained from rats orally given APE also inhibited hepatoma proliferation and invasion when added to the culture medium. Subsequently, the effect of dietary APE on growth and the metastasis of AH109A hepatomas were investigated in vivo. APE reduced the growth and metastasis of solid hepatomas and significantly suppressed the serum lipid peroxide level in rats transplanted with AH109A. APE also suppressed the serum very-low-density lipoprotein + low-density lipoprotein (VLDL + LDL)-cholesterol level. These in vitro and in vivo findings suggest that APE has anti-hepatoma activities.