黄河首曲流域草地生态与自然环境退化成因及对策研究

近50年来黄河首曲流域草场退化、沙化,水土流失,生物多样性减少,生态系统功能弱化.分析了黄河首曲流域气候、生态观测资料及统计资料,结果表明:造成生态与自然环境退化的主要原因是气候变化和环境蠕变.黄河首曲大部分区域降水量年际变化呈下降趋势,气温年际变化呈上升趋势,增温速度均大于全国增温速度.草地年干燥指数呈显著上升趋势,20世纪80年代末至2004年明显趋于干旱化,气候变化是草地生态退化的自然诱发因素.超载过牧、滥采乱挖、人为破坏、生物链失衡等环境蠕变是造成生态退化的人为因素.二者共同作用导致黄河首曲流域草地与湿地生态与自然环境退化.控制放牧、防止滥采乱挖、建立自然生态保护区是维护该区域生态系统平衡的措施.     

植物化学生态学中的克生作用在草业上的表现

为了解植物生化他感作用在草业（田间杂草）中的作用，１９８６－１９８８年通过查阅资料并对我国大部分牧区和农区实地考察，证明，在植间广泛存在着因植物次生代谢产物对微生态环境的改变所引起的植物种内和种间生长发育相互促进和抑制的生化他感作用，其中植物间的克生作用（抑制作用）表现的较为明显，而这种作用与草原退化和农田杂草的蔓延有着密切关系。     

塔里木河上游与下游地区天然植被群落特征对比分析

塔里木河是我国干旱区最长的一条内陆河,同时塔里木河流域也是我国生态环境脆弱地区之一,该流域荒漠化程度日益加剧,具体表现为土地沙漠化、土壤盐渍化、草场退化、生物多样性减少等,这些都严重的制约了区域社会经济的可持续发展。本文根据对塔里木河的实际调查资料,分别计算了上、下游典型样地的物种多样性指数、丰富度和均匀度指数,对塔里木河上、下游地区的天然植被的群落特征进行了对比分析。结果表明:塔里木河流域内的植物区系组成贫乏,群落结构简单,随着上游至下游水量的减少,下游地区天然植被较上游地区普遍退化,植物种类及群落类型均少于上游地区,生态系统非常脆弱。     

民勤沙区主要植物群落退化特征及其演替趋势分析

优势种植物密度和优势种盖度以及全部植物密度和盖度在样方间均存在不同程度的差异,表明民勤的植物生长在受干旱荒漠环境影响的同时,局部小环境对植物的分布和生长有显著影响。沙蒿当年幼苗密度最大,但幼苗的成活率很低,群落的投影盖度越小,则当年幼苗密度越大;梭梭不能实现自然更新;沙拐枣的生态位宽度较大,各年龄小苗均存在,自然更新能力强。在民勤沙区人工梭梭林普遍退化,尤其在西沙窝一带,梭梭人工林退化更为严重,有被沙拐枣取代的趋势。由于梭梭群落均为人工林,群落内地表异质性较大,因此,草本植物种类较多。     

草原退化的后果及深层原因探讨

草原退化是在不合理利用，草原生态系统结构失调，生产和生态功能衰退的过程，严重的草原退化所引起的，不仅是草地畜牧业生产的下降，还会造成人们生存环境的恶化，甚至导致人类文明的毁灭，退化不但与各种不合理利用等直接因素有关，尤其与社会经济体制，人口压力，生物生态学机理等深层因素有关，深刻揭示和认识这些问题，将有助于草原退化的防治。     

STAGING OF LUMBAR INTER VERTEBRAL DISC DEGENERATION IN NONCHONDRODYSTROPHIC DOGS USING LOW-FIELD MAGNETIC RESONANCE IMAGING

Recognition of disc degeneration in vivo is important in the investigation of the pathophysiology of intervertebral disc disease as well as the assessment of patients. The purpose of this study was to compare low-field magnetic resonance imaging and histopathologic findings of disc degeneration in the canine caudal lumbar spine. A simple four-stage classification system for disc degeneration is proposed. Most common signs of disc degeneration in magnetic resonance imaging included nuclear clefts, decreased signal intensity of the nucleus pulposus and tears of the annulus fibrosus, or disc herniations. The association between magnetic resonance images and histopathologic findings was highly significant. A sensitivity of 100% and specificity of 79% for magnetic resonance imaging was calculated using histopathology as the gold standard.     

Time-course changes of hippocalcin expression in the mouse hippocampus following pilocarpine-induced status epilepticus

Hippocalcin participates in the maintenance of neuronal calcium homeostasis. In the present study, we examined the time-course changes of neuronal degeneration and hippocalcin protein level in the mouse hippocampus following pilocarpine-induced status epilepticus (SE). Marked neuronal degeneration was observed in the hippocampus after SE in a time-dependent manner, although neuronal degeneration differed according to the hippocampal subregions. Almost no hippocalcin immunoreactivity was detected in the pyramidal neurons of the cornu ammonis 1 (CA1) region from 6 h after SE. However, many pyramidal neurons in the CA2 region showed hippocalcin immunoreactivity until 24 h after SE. In the CA3 region, only a few hippocalcin immunoreactive cells were observed at 12 h after SE, and almost no hippocalcin immunoreactivity was observed in the pyramidal neurons from 24 h after SE. Hippocalcin immunoreactivity in the polymorphic cells of the dentate gyrus was markedly decreased from 6 h after SE. In addition, hippocalcin protein level in the hippocampus began to decrease from 6 h after SE, and was significantly decreased at 24 h and 48 h after pilocarpine-induced SE. These results indicate that marked reduction of hippocalcin level may be closely related to neuronal degeneration in the hippocampus following pilocarpine-induced SE.     

Histological Changes in the Deep Branch of the Lateral Palmar Nerve of Horses With Induced Proximal Suspensory Desmitis

Desmitis of the proximal aspect of the suspensory ligament, or interosseus medius muscle, of the pelvic or thoracic limb is a commonly diagnosed cause of lameness of performance horses. Despite medical treatments available for horses with proximal suspensory desmitis (PSD), most horses treated medically for PSD of a pelvic limb remain persistently lame; this persistent lameness may be the result of a neuropathy caused by compression of nerves by an enlarged suspensory ligament. Few horses with PSD of a thoracic limb remain persistently lame. Based on the results of reports citing successful treatment of horses chronically lame because of PSD of a pelvic or thoracic limb, by excising a portion of the deep branch of the lateral plantar or palmar nerve (DBLPlN/DBLPaN), we theorized that persistent lameness of horses caused by PSD of a thoracic limb may also be due to compression of nerves that supply the ligament. The aim of this study was to determine if histological signs of compression neuropathy of the DBLPaN are present in horses with PSD in a thoracic limb. To test this hypothesis, we induced PSD by instilling collagenase into the ligament and then examined the DBLPaN after harvesting this nerve 2 months later. We found that the DBLPaNs of all treated limbs showed histologic changes suggestive of nerve compression. We conclude that studies examining the DBLPaN of horses with naturally occurring PSD for histological evidence of neuropathy are warranted.     

从西部大开发透视阿拉善盟荒漠草地生态建设的意义与对策

由于人为破坏和自然因素的影响，致使阿拉善盟荒漠草地严重退化，特别是草地植被的破坏，引起生态环境的恶化，对阿拉善盟17万居民的生产生活构成严重威胁，乃至对西北，华北地区生态环境的可持续发展构成严重威胁，本文通过对阿拉善盟荒漠草地的退化现状及成因分析，阐述了草地生态建设的意义和对策，对该地区荒漠草地生态建设具有一定的指导意义。