Variations in spring leaf phenology and leaf freezing damage of common woody species in China北大核心CSCD     

陶泽兴  戴君虎 《地理科学进展》2023,(4):766-781

Freezing damage results in the dehydration of plant cells and reduces the photosynthetic capacity of plants, which causes significant losses to ecology and economy. Over the past 40 years, global warming has reduced the frequency and intensity of frost events while bringing forward the spring phenology of plants, increasing the exposure of their leaves and flowers to harsh cold temperatures. Therefore, the dual effects of climate warming should be considered in order to accurately assess the changes of plant freezing damage. To date, there is no systematic analysis of plant freezing damage in different climatic regions of China. Based on phenological observation records from the China Phenological Observation Network, leaf frost damage of four common woody plants (Ulmus pumila, Robinia pseudoacacia, Salix babylonica, Fraxinus chinensis) in the spring over the past 40 years was calculated, and the spatio-temporal patterns were analyzed. We also investigated the change in the occurrence time of maximum frost damage (TMFD) and its relationship with plant phenology. The results show that: 1) Most species presented an overall trend towards an earlier leaf unfolding date, and the advancing trend was significant and greater than 1 d/a in about 60% of the regions (P<0.05). 2) The TMFD occurred earlier in 72.22%-83.03% of the regions, which was closely related to plants' earlier leaf unfolding date. The TMFD of all species advanced the most (8.3 days) in the temperate climate zone, followed by the warm temperate, subtropical, plateau, and cold temperate zones. 3) The leaves of U. pumila, R. pseudoacacia and S. babylonica suffered more freezing damage in the spring, and the most significant freezing damage was mainly found in the north of 50°N region and part of the west of the Qinghai-Tibet Plateau. In comparison, the leaves of F. chinensis suffered less frost damage due to later leaf unfolding date and stronger leaf frost resistance. With regard to interannual variations, the average freezing damage of U. pumila, R. pseudoacacia and S. babylonica increased significantly (P<0.05), but that of F. chinensis did not change obviously. In addition, the freezing damage of U. pumila and S. babylonica increased the most in the cold temperate zone, while that of R. pseudoacacia increased in about 10% of the regions in the plateau climate zone, and 3%-6% of the regions in the cold temperate, temperate, and warm temperate climate zones. The freezing damage of F. chinensis merely increased in the warm temperate zone. The results of this study can provide a reference for assessing the risk of plant freezing damage accurately and help develop regional-specific response and adaptation strategies to climate change. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved.  相似文献   

基于ALBERT模型的园林植物知识实体与关系抽取方法     

陈晓玲  唐丽玉  胡颖  江锋  彭巍  冯先超 《地球信息科学学报》2021,23(7):1208-1220

园林植物知识图谱可为顾及区域适应性、观赏性和生态性等因子的绿化树种的选型提供知识支持。植物描述文本的实体识别及关系抽取是知识图谱构建的关键环节。针对植物领域未有公开的标注数据集,本文阐述了园林植物数据集的构建流程,定义了园林植物的概念体系结构,完成了园林植物语料库的构建。针对现有Word2vec、ELMo和BERT等语言模型存在无法解决多义词、融合上下文能力差、运行速度慢等缺点,提出了嵌入ALBERT（A Lite BERT）预训练语言模型的实体识别和关系抽取模型。ALBERT预训练的动态词向量能够有效地表示文本特征,将其分别输入到BiGRU-CRF命名实体识别模型和BiGRU-Attention关系抽取模型中进行训练,进一步提升实体识别和关系抽取的效果。在园林植物语料库上进行方法的有效性验证,结果表明ALBERT-BiGRU-CRF命名实体识别模型的F₁值为0.9517,ALBERT-BiGRU-Attention关系抽取模型的F₁值为0.9161,相较于经典的语言模型（如Word2vec、ELMo和BERT等）性能有较为显著的提升。因此基于ALBERT模型的实体与关系抽取任务能有效提高识别分类效果,可将其应用于植物描述文本的实体关系抽取任务中,为园林植物知识图谱自动构建提供方法。  相似文献   

澜沧江某大型水电站左岸岩体结构面发育特征及形成机制分析     

刘涛  王运生 《地质灾害与环境保护》2004,15(1):70-74

现场调研表明,该大型水电站左岸结构面发育在横向上具有明显的不均一性和分区性。断层Fl、F3为规模最大的两条断层,控制左岸块体分区;断层F3等小断层、破碎带导致岩体性状较差;密集于断层F1、F3之间的结构面使岩体工程地质性状最差。综合分析认为．这些结构面及其分布差异是古生代以来岩浆活动及多期构造作用复合作用所致。笔者将从地质背景、结构面特征诸方面,深入分析这些结构面的形成机制及形成机制对左岸工程岩体稳定性的影响。  相似文献   

DUN AND BRADSTREET'S MARKET IDENTIFIERS AND ECONOMIC GEOGRAPHY*     

Alex Schwartz 《The Professional geographer》1987,39(2):166-172

An increasing number of studies of business start-ups, closings, and relocations rely on a single data base, DUNS Market Identifiers. This data file to U.S. business establishments provides researchers with essential information about individual firms and establishments. It also exhibits serveral idiosyncracies and requires careful consideration of the meaning of such basic terms as “location”and “firm.”Drawing from a recent survey of 500 New Jersey firms. I consider some of the methodological amd conceptual issues Dun and Bradstreet data pose for industrial location analysts. The Dun and Bradstreet listings exaggerate the exaggerate the incidence and magnitude of establishment openings and closing.  相似文献   

环境植物样品中铜铅锌铁锰的测定     

马欣  丛玉梅  邵文君 《国土资源》1995,(1)

将环境植物样品在４００─５００℃灰化，用硝酸、氢氟酸和高氯酸分解，用盐酸（１＋１）提取，控制２％─３％的盐酸介质，用火焰原子吸收分光光度法测定环境植物样品中的微量铜、铅、锌、铁、锰。该方法简单、快速、可靠。对环境植物标准样品的测定结果理想。  相似文献   

Flow modelling in a high mountain valley equipped with hydropower plants: Rio Zongo Valley,Cordillera Real,Bolivia     

Yvan Caballero  Pierre Chevallier  Robert Gallaire  Ramiro Pillco 《水文研究》2004,18(5):939-957

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浮床无土栽培植物控制池塘富营养化水质   总被引：12，自引：0，他引：12  

邴旭文  陈家长 《广东海洋大学学报》2001,21(3):29-33

采用浮床无土栽培技术,在池塘水面种植景观植物--陆生植物美人蕉(Cana generalis  相似文献   

浅析宁波盆地膏盐地层的时代──兼对“宁波盆地北部的长河群”之时代质疑     

鞠天吟 《浙江国土资源》1995,(1)

宁波盆地地下揭示的一套包含暗色膏硝质泥岩、泥质白云岩在内的紫红、灰紫色泥岩、棕褐色砂砾岩、细砂岩和玻屑凝灰岩的地层，均称方岩组，内含膏盐并具油色显示。对其时代有早、晚白垩世和早第三纪之认识，笔者从70～90年代地质工作中所获化石分析认为，虽然宁波盆地这一层位含化石不丰，但从分布及数量上比较，相对占优势的应该是孢粉和植物化石，其时代意见也较为一致，指示为早白垩世。  相似文献   

玉米秸秆带状覆盖对西北旱地土壤温度及马铃薯产量的影响   总被引：2，自引：0，他引：2  

李辉  吴建民  柴守玺  常磊  韩凡香  程宏波 《中国沙漠》2018,38(3):592-599

设黑膜大垄（M1）、玉米秸秆带状平覆（M2）、玉米秸秆带状垄沟覆杆（M3）和不覆盖露地平作（CK）4个处理进行田间小区试验,对比研究不同覆盖方式对西北旱地土壤温度及马铃薯产量的影响。结果表明：M1较CK提高全生育期土壤温度0.98℃,主要提高了块茎膨大期5 cm土层（2015年）及淀粉积累期10 cm土层（2016年）的土壤温度;M2、M3较CK降低全生育期土壤温度1.06℃、0.59℃,主要降低了块茎形成期10 cm土层的土壤温度。两年M1、M2、M3分别平均较CK增产11.68%、21.74%、16.88%。产量与淀粉积累期至收获期单株结薯数、单株产量正相关（r=0.064~0.766）,覆盖处理显著较CK提高淀粉积累期单株结薯数及单株产量,平水年以M1最好,偏旱年以M2最好。  相似文献   

气候变化对植物多样性的影响研究综述     

何远政  黄文达  赵昕  吕朋  王怀海 《中国沙漠》2021,41(1):59-66

植物多样性是生态系统结构和功能的基础,气候变化已对其产生了深刻的影响,甚至于严重威胁。植物多样性的减少或丧失必然会影响生态系统结构和功能的稳定性,导致严重的生态、经济和社会后果。植物多样性对气候变化的响应受控于气温和水分的动态平衡。本文系统总结了气候变暖和降水格局变化对植物多样性的影响,分析了气候变化对不同生态系统、群落类型、尺度范围（全球尺度、区域尺度、局地尺度）内植物多样性的影响,并归纳了差异的主要影响因素。最后对未来的研究方向做了展望。  相似文献