Anatomic Study of Female Sterility of Pinus tabulaeformis Carr.

The anatomic research on the mutant clone of Pinus tabulaeformis Carr.in the seed orchard in Xingcheng,Liaoning Provinces was carried out.The female cone of the mutant clone looked like normal,but its ovules degenerated in early stage.This paper trics to find out the reason and time of ovule abortion.It seems that the ovule abortion is probably caused by female sterility because the microspores of this mutant clone were normal.Through the serial observations on the one-year-old macrosporangiates and the ovules of two-year-old female cones of mutant and normal clone,it is found that the reason of ovule abortion in mutant clone is the failure of the mitosis of free nuclei in the female gametophyte,and the time is about in the early April.     

内蒙古自治区三北工程区退化林草修复对策与建议

内蒙古自治区实施三北防护林体系建设工程已有40 a,近年来,一些林分由于适应问题、老化问题发生的退化（或衰退）现象逐步显现。文章根据2021年内蒙古自治区实施的内蒙古三北工程退化林草摸底调查工作成果,介绍了全区三北防护林工程区林草退化的现状,分析了工程区林草退化的主要原因,并在此基础上,对下一步三北工程区退化林草修复以及生态建设工作提出了对策与建议。     

Evaluation of the adaptability and response of indigenous trees to assisted rehabilitation on the degraded hillsides of Kuriftu Lake Catchment （Debre Zeit,Ethiopia）

Removal of trees and shrubs from hillsides exposes a site to erosion that threatens soil aggregation and stability. The present study aimed at evaluating the performance of five indigenous tree species in rehabilitation of degraded hillsides of Kuriftu Lake Catchment and the role of water harvesting structures. Adaptability varied by tree species and water harvesting structures significantly augmented seedling es-tablishment for some tree species. Height ofAcacia abyssinicaplanted on steeper slopes （18%-27%） without infiltration pits was lower than for conspecifics planted with infiltration pits.Dodonaea angustifolia wasproved to be best adapted to the siteand showed no need for water harvesting regardless of planting position across the degraded hillside. Planting ofAcacia seyalshould be restricted to gentler slopes （0-17%） with infiltration pits： tree height declined significantly on steep slopes without infiltration pits.Olea africanaperformed better on gentle slopes with pits but also grew well on steeper slopes with pits.Euclea schim-periwasproved to be least effective of the species evaluated in this study.     

内蒙古三北防护林工程区林分退化现状与特征分析

准确掌握三北防护林工程内蒙古工程区退化林分面积、分布以及退化类型与程度,对科学安排修复任务,实行精准修复,提升修复效果,具有重要作用。研究结果表明,内蒙古三北防护林工程区退化林面积达到301.9万公顷,退化乔木林面积50.9万公顷,退化灌木林面积251.0万公顷,退化林总蓄积2598.0万立方米。工程区退化乔木林以重度退化为主,退化灌木林以中度退化为主;杨树、榆树、柠条、锦鸡儿是主要的退化树种,其中以杨树尤为突出;退化林中成、过熟林占比较大;树种单一,林分老化是导致工程区林分退化的主要原因。     

内蒙古敖汉旗退化林分改造技术要点

指出了敖汉旗属于典型的干旱、半干旱地区,全旗总土地面积1245万亩,其中林业用地601万亩,森林覆盖率44.07%。由于近年来连续极端气候条件影响,导致全旗出现大面积的退化林分,据调查现有退化林分202.1万亩,占林分总面积的38.69%。根据这一现状,分析了其中的原因,划分林分退化等级,因地制宜,确定修复类型,提出了适宜该地区的退化林分改造技术措施,然后按先急后缓、先重后轻的原则,分区域、分类型安排年度改造计划。     

森林退化评价指标与类型划分初步研究

该文对比阐述了国内外关于森林退化的涵义、评价指标、类型划分等内容,基于与区域相比更小的微观尺度提出了森林退化评价指标体系,包括森林结构、生态功能、系统稳定性等3个方面的一级指标和群落结构、林层结构、树种结构、植被总覆盖度、郁闭度、自然度、森林生产力、天然更新、森林健康、龄组等10个二级指标;以及森林退化类型:包括森林群落完全丧失型、森林群落基本丧失型、森林群落残次型3种类型,其中森林群落残次型又可细分为林相残破型、林相老化型、林分衰退型、结构简单型、自然灾害型等5种小类型。     

The current status, threats and protection way of Sanjiang Plain wetland, Northeast China

The Sanjiang Plain is a vast area of alluvial floodplains and low hills in northeast Heilongjiang Province. It is the largest tract of wetlands in China and East Asia outside of Siberia. 28 wetland nature reserves exist on the Sanjiang Plain, and three of them have been listed as wetlands of international importance to water bird conservation by the Ramsar Convention Bureau. The wetlands of Sanjiang Plain are noteworthy for its rich biodiversity, but they continue to decline in area and deteriorate in quality currently. The main threats or constrains, immediate cause, root cause and required response are analyzed in this paper, and the four aspects opinion such as improvement of watershed management, enhancement of protection and restoration of habitats and biodiversity, alternative livelihoods of rural residents living in and near natural wetland reserve, and reinforcement of capacity building of natural reserves are brought forward as the effective measures for the Sanjiang Plain wetland protection.     

中国湿地退化状况评价指标体系研究

选取不同类型退化湿地的典型退化指标,如湿地面积变化率、水源补给状况、地表水水质、濒危物种数和种群数量变化率、植被覆盖变化率等作为湿地退化状况的评价指标,将湿地的退化程度划分为4个等级:未退化、轻度退化、重度退化和极度退化,并对10处滨海国际重要湿地和22处内陆国际重要湿地的退化状况进行了评价。评价结果表明,2个湿地是严重退化,1个湿地是轻度退化,其余29个湿地是未退化。     

浅谈建昌县退化防护林的现状与修复对策

防护林对生态环境的作用十分重要，但由于多年来受各种自然灾害的影响及树种单一等原因造成防护林大面积退化，降低了防护林的防护作用。通过对防护林退化成因的调查分析，提出了对退化防护林修复的对策，对该地区今后防护林修复及改造具有一定的参考价值。     

紧密结合生产搞好退化土地治理技术的研究

科研实践能开拓科研工作者的研究思路，使之产生飞跃，本文以科研实践和自身体会论及研究方向。     

中国湿地资源的退化及其原因分析

由于长期以来湿地的效益和功能并未得到社会公众和政府部门的重视 ,造成湿地的盲目开发 ,湿地面积和湿地资源日益减少 ,使中国湿地面临着退化的严重威胁。以三江平原、长江中游湖泊湿地等湿地资源退化为例说明了中国湿地资源的退化 ,并分析了目前湿地资源退化的主要原因。在此基础上 ,提出了我国湿地资源保护的主要对策。     

Degraded Ecosystem and its Rehabilitating Measures in Sandy Areas of North China

Ecosystem degradation occurs in parallel with desertification process in sandy areas of North China. The vast sandy areas in North China are characterized with flexible environments and fragile ecosystems as well as intensive human activities. Due to the annual precipitation gradient decreases from east to west in North China, the whole sandy region falls into 3 main climatic zones: arid, semi-arid and dry sub-humid zones.The ecosystems in each type of climatic zones are different in climatic conditions, human activities, cultural dimensions, vegetation covers, landscapes, and causes and processes of ecosystem degradation. Therefore, the most effective rehabilitation measures of degraded ecosystems in different types of the climatic zones are also different. For the arid sandy areas, vegetation rehabilitation of degraded ecosystems needs to be completely closed, assisting with artificial measures, such as plantation, irrigation or others. For semi-arid sandy areas, the effective measures of vegetation re     

黑木耳菌种退化原因浅析

黑木耳Auricula auricula(L.ex Hook)Un-derw栽培丰产的决定因素是综合的、多方面的,但最关键的决定因素是菌种的优良。近两年来多方面反映段木栽培黑木耳产量连年下降,究其原因菌种退化是主要因素;其次是栽培摆放场地多年不消毒灭杂菌。 据对黑木耳生物学特性和转管扩接次数对黑木耳产量影响的实验研究结果证明,引起黑木耳菌种退化的原因有三;     

草坪退化的原因及防治措施

在园林绿化建设中，草坪作为新型绿化材料目前已得到广泛的应用。草坪不仅丰富园景，而且有广阔清新的特点，并对防尘、降温、净化空气、降低嗓音，防止土壤侵蚀、改善生态环境等方面有显著作用。由于草坪近几年才兴起来，管理者种植经验缺乏，养护管理跟不上，草坪出现色泽淡黄，质地较粗，枯死，斑秃，生长不旺，外形不均匀，达不到良好的观赏效果和使用价值。因此，如何防止草坪退化就显得至关重要。１　土壤质地对草坪的影响一般草坪退化原因是土壤的质地变劣，如土壤板结，排水不良，透气性不好，土壤ｐＨ值的变化等都会影响草坪根系的…     

半干旱农牧交错区人工林退化:概化模型和现状评价

在干旱半干旱地区,造林通常被作为荒漠化防治最为有效的措施之一,然而这一区域人工林退化也是不可回避的事实。本文以半干旱农牧交错区的内蒙古伊金霍洛旗为例,对其林地退化状况进行评价。根据野外调查结果我们建立了一个林地退化概化模型,据此筛选出湿润指数、植被指数、土壤类型和土壤侵蚀模数4个评价指标,并采用GIS对该区人工林退化状况进行评价。结果表明,在336.09km2人工林中,退化面积达311.35km2,其中轻度、中度和重度退化面积分别为78.97,119.73和112.65km2。退化人工林的防治重点应放在现有林的改良和造林植物种特别是灌木种的选择上。图4参15。     

康定县退化草地空间分布与治理对策浅析

草地是康定县绿色植被生态系统的主体,是保持康定生态平衡的重要一环。基于对康定县的草地退化情况进行评价,依据退化程度评价为4级,即无明显退化草地、轻度退化草地、中度退化草地以及重度退化草地。根据评价结果,结合研究区的高程、坡度、坡向、居民点信息,分析康定县退化草地的分布情况,并对草地退化原因进行了分析,提出了退化草地的恢复与治理对策。     

松林生态系统退化评价及其与马尾松毛虫灾害关系的研究

通过对长沙县丘陵区马尾松林生态系统进行调查研究,选取生物途径、生境途径以及生态系统功能途径3个诊断途径,采取多途径综合诊断的方法对丘陵区马尾松林生态系统退化程度进行诊断,确认其退化程度,在此基础上分析松林生态系统退化程度与马尾松毛虫灾害的关系。结果表明马尾松毛虫灾害发生程度与生态系统退化程度关系密切。生态系统退化越严重的地区,马尾松毛虫灾害越严重,退化较轻的地区,马尾松毛虫灾害较轻或不发生。     

关于实现真正意义的生态旅游的思考

在1999年生态环境旅游年里，众多旅游区纷纷推出了冠以“生态旅游”之名的活动，结果是由于对“生态”的泛泛理解使得保护区的环境遭受了严重危害。据统计，在已开展“生态旅游”活动的全国自然保护区中，有24％的自然保护区及其保护对象受到了损害；11％的保护区出现了旅游资     

恢复生态学理论对退化生态系统恢复的重要性

本文综述了恢复生态学的概念、研究对象、研究内容，并应用恢复生态学理论对几类退化生态系统(湿地，喀斯特，采矿地，荒漠)的恢复和重建进行论述。表明退化生态系统的恢复是以恢复生态学理论为依据的，恢复生态学理论对退化生态系统的恢复和重建起到积极的指导作用。恢复生态学的理论基础是生态演替，退化生态系统恢复的实质是群落演替。在此理论指导下。首先排除干扰，再建立生产者、消费者、分解者和微环境系统对退化生态系统进行生态恢复。