云南松天然林区植物群落结构的空间动态研究

于2005年4月采用中点四分法对云南省禄丰县一平浪林场云南松天然林区植物群落结构及空间动态进行了实地调查研究.结果表明:从山坡上部到下部,物种的组成越来越丰富,其中的优势种群云南松属于衰退型、滇油杉属于增长型、黄毛青冈属于稳定型.根据更新层的重要值来判断,山坡上部将演替成为以滇油杉为主的单优群落;山坡中部将演替成为滇油杉和黄毛青冈为主的针叶、阔叶混交林;山坡下部将演替成为以黄毛青冈为主的常绿阔叶林.研究还表明,在林冠层中,除了滇油杉在山坡上部为聚集分布外,其他树种的分布格局均呈随机分布;在更新层中,优势种类均为聚集分布.     

基于无人机的昆明海口林场宽地坝林区植物群落建群种格局研究

建群种是植物群落优势层中的主要物种,对群落环境有显著控制作用。空间格局是植物种群的基本特征之一,探讨建群种的空间格局是理解生物与生境之间关系和认识群落生态过程的有效途径。空间格局特征包括种群空间关联性及其空间分布型。利用无人机技术,获取昆明海口林场半湿润常绿阔叶林和落叶栎类林的多光谱遥感影像,采用ArcGIS Pro软件进行遥感影像分类并提取滇青冈(Cyclobalanopsis glaucoides)、光叶石栎(Lithocarpus mairei)、滇石栎(L.dealbatus)、栓皮栎(Quercus variabilis)、槲栎(Q.aliena)植株树冠中心点空间坐标。在Programita Febrero 2014软件中进点格局分析。结果表明:各物种10m以下呈均匀分布或随机,随尺度增加,渐渐表现为聚集分布。光叶石栎种群和滇石栎种群空间关联性表现为负相关。     

藏东南川滇高山栎种群不同生长阶段的空间格局与关联性

运用点格局分析方法中Ripley L函数,对藏东南川滇高山栎种群不同生长阶段的空间格局及其关联性进行分析.结果表明： 藏东南川滇高山栎种群径级结构呈单峰型,小树与中树的数量在整个种群中占绝对优势,整个种群自然更新状况良好,属增长型种群.川滇高山栎种群在从小树发育到大树的过程中,小树、中树在小尺度上均呈明显的聚集分布,而大树在整个尺度上基本上呈随机分布.小树与中树、大树间在小尺度上有显著的相关性,而中树与大树不相关.川滇高山栎种群在从小树、中树发育到大树的过程中,其空间格局由聚集分布到随机分布.川滇高山栎种群的自然更新受种间竞争的影响,也受种内竞争的影响.在自然环境条件相似下,影响川滇高山栎种群分布格局的最主要因素是其自身的生物、生态学特性.     

皖北石灰岩山地青檀种群不同发育阶段的点格局分析

基于皖北石灰岩山地青檀次生林的样地调查数据,采用空间代替时间和点格局O-ring统计法,研究了青檀种群的径级结构、不同发育阶段的空间分布格局及其相互关联性.结果表明:(1)不同样地青檀种群的径级结构大体呈倒“J”型,各径级均有个体分布,但主要集中在幼苗、幼树阶段,中树和大树较少,种群均属增长型.(2)幼苗、幼树和中树在个别小尺度上呈现出明显的聚集分布,且皇藏峪种群的聚集强度显著高于相山种群;随着尺度的增加,个体趋于随机分布.成树阶段的青檀个体均表现为随机分布或接近均匀分布.(3)各发育阶段间的空间关联主要表现在中、小尺度上,随着空间尺度的增加,空间关联性不显著.青檀种群结构和空间格局主要受群落生境的异质性、自身生物学特性(尤其是克隆繁殖)以及人为活动的干扰等因素影响.     

Spatial distribution patterns and association of Picea crassifolia population in Dayekou Basin of Qilian Mountains,northwestern China

研究青海云杉(Picea crassifolia)种群不同发育阶段的空间分布格局及其关联性, 能揭示其种群的发展规律, 推断其潜在的生态学过程或影响机制, 进而为该种群的配置、种植和森林的经营与管理等提供指导。该研究基于祁连山大野口流域10.2 hm²青海云杉动态监测样地调查资料, 分析了青海云杉群落的物种组成和径级结构, 并采用点格局方法, 通过单变量成对相关函数和双变量成对相关函数对不同年龄阶段青海云杉种群的空间分布格局及其空间关联性进行分析。结果表明: (1)青海云杉种群的径级结构呈倒“J”型分布, 属增长型种群, 种群自然更新状况良好。(2)青海云杉种群4个径级的个体在小尺度上呈聚集分布, 但随着空间尺度的增大, 聚集强度逐渐减弱, 趋向随机分布; 较小径级的个体常呈聚集分布, 而随着径级增大, 也趋向于随机分布。(3)青海云杉大树个体在小尺度(<4 m)范围内与其他径级个体都呈负关联, 随着尺度的增加, 大树与幼树表现出正关联且关联性随尺度的增加而减弱, 而与小树、中树则表现为无关联或者微弱的负关联; 径级相近的个体空间关联性为正关联或无关联, 随着个体径级间差距增大, 空间关联性转变为无关联或负关联。研究表明, 祁连山大野口流域青海云杉种群的分布格局及其关联性随空间尺度和发育阶段而变化, 这是由种群自身的生物生态学特性、种内种间关系以及环境条件共同作用的结果。     

常绿阔叶林石栎和青冈种群生活史特征与空间分布格局

以中亚热带低山丘陵常绿阔叶林石栎-青冈群落为研究对象,采用相邻格子法在湖南省长沙县大山冲林场建立1hm2永久性监测样地,通过编制静态生命表绘制种群年龄结构图和存活曲线以及应用Ripley’s K函数,研究了石栎和青冈的生活史动态、空间点格局以及不同生活史的空间关联性。结果显示:(1)两种群的死亡率随径级的增加呈上升趋势,在幼树(Ⅰ级)到小树(Ⅱ级)阶段均达到死亡高峰;两种群均属于增长型年龄结构,生命曲线接近于Ⅰ型(曲线凸型)。(2)分布格局主要呈聚集分布,聚集强度随空间距离的增大而增强,随年龄的增大石栎种群呈下降趋势,青冈种群呈先减弱后增强的趋势。(3)石栎和青冈的幼树、小树在小尺度上与中树、大树显著正关联,且青冈在t15m的尺度上小树和大树亦显著正关联。研究表明,物种的生物学特征和种内、种间竞争是影响石栎、青冈种群生存力的重要因素;种子扩散、萌芽繁殖、生境特化和负密度效应是维持石栎和青冈种群空间格局的主要驱动因子。     

木林子大样地两个木姜子属物种空间分布格局及关联性

该文以湖北木林子国家级自然保护区15 hm2大样地同属物种[木姜子(Litsea pungens)和黄丹木姜子(L. elongata)]为研究对象,通过成对相关函数和不同零模型(完全空间随机模型、异质泊松模型和先决条件模型)的方法分析两个物种的空间分布格局、种内和种间空间关联性,从同属物种的空间分布格局角度探讨群落的构建机制。结果表明:(1)种群空间分布格局研究中,两个种的空间分布格局大致为聚集分布。基于CSR零模型,木姜子和不同径级(幼树、小树、中树和成年树)的聚集尺度分别为0~114 m、0~103 m、0~56 m、0~34 m和0~16 m,黄丹木姜子和不同径级的聚集尺度分别为0~150 m、0~150 m、0~59 m、0~56m和0~14 m;基于HP零模型,木姜子整体的空间分布格局聚集尺度为0~23 m,其中幼树、小树和中树均在0~22 m呈现聚集分布,成年树仅在0~3 m尺度上表现为聚集分布,黄丹木姜子整体的空间分布格局聚集尺度为0~36 m、140~150 m,各径级的聚集尺度分别为0~35 m、0~35 m、0~12 m和0~6 m。(2)种内关联性研究中,木姜子和黄丹木姜子不同径级个体种内关联在小尺度上基本呈现正关联,随着尺度的增大变为微弱的无关联或负关联。(3)种间关联研究中,木姜子对黄丹木姜子和黄丹木姜子对木姜子的空间关系大致相同。总体上,两物种之间均体现为在30 m尺度内对另外一个物种呈现正关联,40~68 m尺度内呈现负关联;不同径级之间都表现为无关联,偶尔出现正关联或负关联。研究认为,种群空间分布格局基本上为聚集分布,其主要受到生境异质性和扩散限制的影响,木林子大样地中木姜子和黄丹木姜子空间分布格局存在相似性,而不同的生境偏好可能是导致两同属物种共存的原因。     

山西灵空山刺五加种群空间分布格局及种间空间关联性

以山西灵空山自然保护区刺五加(Acanthopanax senticosus(Rupr.Maxim.)Harms)种群为对象,采用空间点格局方法中的Ripley’s K函数,对刺五加种群不同龄级的空间分布格局及其与主要灌木物种间的空间关联性进行研究,并对种群空间分布格局进行可视化解析。结果显示,刺五加种群中幼年个体数量多,径级结构呈金字塔型,为增长型种群,能够实现持续更新;刺五加种群的径级Ⅰ在小尺度上呈聚集分布,随着尺度增大出现随机分布;径级Ⅱ、Ⅲ、Ⅳ在全尺度上呈聚集分布,径级Ⅴ、Ⅵ在小尺度上为聚集分布,随着龄级和空间尺度的增大,刺五加种群聚集强度渐弱,呈现随机分布;刺五加种内关联在全尺度上呈正相关,但与群落中主要灌木在小尺度上呈不相关或负相关,在大尺度上呈负相关。研究表明刺五加的生长条件较为适宜,并可以通过相互之间的庇护作用,减弱种内竞争,但与其他树种间存在强烈竞争,生存现状较差,在群落中处于劣势。     

荒漠绿洲过渡带柽柳种群结构与空间格局动态

在塔克拉玛干沙漠北缘荒漠绿洲过渡带设置1 hm2研究样地,应用相邻格子法进行每木调查,从径级结构、空间分布格局、生命表、存活曲线和时间序列等方面研究柽柳种群结构与空间格局动态及其形成机理。结果表明:荒漠绿洲过渡带柽柳群落结构简单、物种稀少,多为单优群落。柽柳种群径级与高度结构均呈纺锤型,属衰退型种群;存活数、期望寿命(ex)随径级增加而降低,存活曲线接近DeeveyⅡ型,小径级死亡率、消失率与高度级失稳率较高,未来小径级、大径级灌木数量分别随时间推移减少与显著增多,更新资源匮乏使种群走向衰败。柽柳种群空间格局总体上为聚集分布,幼苗、小径级灌木为聚集分布,中、大径级灌木则为随机分布;不同径级的空间格局随尺度变化明显不同,小径级与大径级灌木分别在3 m、13 m和17—36 m尺度内呈随机分布,其他尺度均呈聚集分布,而中等径级灌木在研究尺度内呈随机分布,这是其繁殖特性、种内竞争、生境异质性与生态适应的结果。小径级与中等径级灌木、小径级与大径级灌木空间关联性分别在≥9 m、7—47 m空间尺度上相互排斥,致使幼小径级生长发育受抑而影响种群稳定。种群多度分布与环境的多元统计分析表明土壤水分、氮素是限制柽柳种群生长、分布和造成种群更新困难、衰退的主要因子。     

桂林喀斯特地区克隆生长红背山麻杆种群的点格局分析

植物空间分布格局是种群自身特性、种间关系以及环境条件综合作用的结果。对植物空间格局和关联性的研究有助于认识植物群落的形成、维持和演替过程。红背山麻杆(Alchornea trewioides(Benth.)Muell.Arg.)是桂林喀斯特地区重要的先锋物种。调查了桂林喀斯特地区以克隆繁殖为主的红背山麻杆群落,采用点格局方法,以Ripley's K函数为基础运用g(r)和L(r)函数对红背山麻杆种群进行点格局以及不同径级之间关联性分析。结果表明:(1)红背山麻杆在小尺度(小于2 m)上表现为聚集分布;在大尺度(大于2 m)上表现为随机分布;(2)3个径级之间在小尺度两两表现为正关联。随着尺度的增大,3径级之间的关联性由正关联转变为无关联或者负关联;(3)在大尺度范围红背山麻杆较大地径的母株对其他母株的克隆小分株产生较强的抑制作用,随着两个径级大小差异增大,它们的空间关联性会逐渐呈无关联或负关联,与径级Ⅰ与径级Ⅱ及径级Ⅱ与径级Ⅲ相比,径级Ⅰ与径级Ⅲ的空间关联性呈较强的负关联。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

Polymorphism in Cepaea Hortensis in marginal populations in Spain

Cepaea hortensis (Mull) is found in Spain only in the western part of the Iberian mountain range. This is the southernmost limit of its range. The most frequent colour is yellow, brown being very rare. The most frequent band patterns are 12345, fused banded and unbanded. There are associations between maximum and minimum temperatures and pink and effectively unbanded yellow phenotypes. The populations may be grouped into two zones, one located in the north and the other in the south of the sampled area. Visual predation was not observed. The marginal populations studied by us were compared with others from Northern Europe, and it was observed that pink snails are more frequent at the southern limit, and unbanded ones at the northern limit. This was interpreted as a climatic selection.