A Field-Based Technique for Teaching about Habitat Fragmentation and Edge Effects     

《The Journal of geography》2012,111(4-5):210-218

Abstract

This article presents a field technique that exposes students to the indirect effects of habitat fragmentation on plant distributions through studying edge effects. This assignment, suited for students in an introductory biogeography or resource geography class, increases students' knowledge of basic biogeographic concepts such as environmental gradients and disturbance in addition to formulating research questions and design. In this exercise, fieldwork can be implemented with simple tools that are easily obtainable and found in most physical geography labs. In this example, student response to the exercise was positive; they indicated that the exercise was a fun and interactive way to learn fundamental biogeographic concepts.  相似文献   

The effect of terrestrial habitat fragmentation on fish populations in small streams: A case study from New Zealand     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(4):269-275

Habitat fragmentation edge effects on riverine fish could have implications for stream fish populations and their management. We examined effects of forest fragmentation on banded kokopu and longfin eels in New Zealand. Banded kokopu prefer small shaded streams with bouldery substrates and instream cover, whereas longfin eels are found in a variety of habitats. We hypothesized that the densities of banded kokopu would be higher in forested than grassland streams, and the densities would be lower around forest margins. We sampled pools in streams flowing from native podocarp/broad-leaf forests into grassland using Gee–Minnow traps. Pools were sampled longitudinally on each stream from >50 m into the forest to >50 m downstream from the forest margin in open grassland. Banded kokopu densities were higher in interior habitat ?50 m into forests than in grassland streams. Fish caught in grassland pools were smaller than in forested pools. Longfin eels were caught in all streams, but numbers and sizes were similar in habitats; thus not likely to generate the pattern observed for banded kokopu. We found that terrestrial habitat fragmentation can impact stream fish populations by decreasing their occupancy of habitats in the vicinity of the boundary between different terrestrial habitats.  相似文献   

基于不同分辨率影像的山区耕地细碎化评价及其尺度效应   总被引：2，自引：0，他引：2  

任红玉  赵宇鸾  李秀彬  葛玉娟 《地理研究》2020,39(6):1283-1294

研究耕地细碎化的尺度效应对山区耕地细碎化遥感监测、耕地整治与可持续利用具有重要意义。选取贵州省坝区孙家村、丘陵区亚鱼村和山地区小坝村3个不同地貌背景的典型村为案例区,在构建细碎化测度模型基础上,量化分析0.1 m、1 m、2 m、5 m、10 m分辨率下耕地细碎化程度的尺度效应。研究结论：① 随着影像分辨率下降,不同地貌背景下的耕作地块特征有明显的尺度效应。② 不同地貌背景下的耕地细碎化程度存在差异,丘陵区的细碎化程度最高,坝区次之,山地区最低。不同影像分辨率下的耕地细碎化程度具有明显的尺度效应,3个典型村的耕地细碎化指数均呈现幂函数式下降;且不同地貌背景的耕地细碎化程度对尺度变化响应程度不同,坝区的耕地细碎化粒度响应最为强烈,丘陵区次之,山地区最弱。③ 以前1个尺度为参照计算耕地细碎化程度的损失精度时,坝区和丘陵区的耕地细碎化程度在影像分辨率由2 m变为5 m时最敏感,山地区小坝村对尺度变化的敏感度从2 m处呈现升高趋势;以基础尺度为参照时,丘陵区的耕地细碎化程度对尺度变化的敏感度最高,山地区次之,坝区最低。研究旨在为山区的耕地细碎化调查、评价以及治理提供借鉴。  相似文献   

城市空间破碎化研究进展及其展望     

朱佩娟  张美芳  贺清云 《世界地理研究》2020,29(5):985-995

在辨析城市空间破碎化概念基础上，以空间破碎化在城市方面研究为主题对1998—2016年间SCI和SSCI数据库中相关文章进行文献计量，对城市空间破碎化研究的内容、方法和进展开展评述。从研究主题看，相关研究多以土地利用、生物多样性保护、环境可持续发展为主题展开，遥感和GIS技术应用是主要的技术趋势。从测度方法看，以土地功能碎化与景观破碎化测度为主，采用景观格局分析的方法，涉及多种景观维度或指数的综合运用。从城市空间相关的研究来看，以现象描述为主，主要着眼于城市内部空间重组，探讨不同类型空间破碎化的表现、产生原因和应对思考。未来城市空间破碎化研究应综合多学科的视角和方法，从空间上一体化运行的相关实体要素出发研究城市空间破碎化内涵、测度方法，结合空间大数据挖掘应用的新技术新方法开展系统综合的研究。  相似文献   

山区耕地细碎化对土地利用集约度影响——以贵州省亚鱼村为例   总被引：2，自引：0，他引：2  

葛玉娟  赵宇鸾  李秀彬 《地理科学进展》2020,39(7):1095-1105

为探索耕地细碎化与土地利用集约度之间的关系,论文以贵州省亚鱼村为例,利用无人机高分辨率影像和农户调查数据,在对比不同通勤距离情景耕地细碎化测度模型准确性的基础上,计算农户耕地细碎化指数,并定量分析不同农户耕地细碎化水平对土地利用集约度的影响。结果表明：对比分析6种通勤距离情景耕地细碎化测度结果,发现农户耕作地块到其宅基地的道路网络距离情景下测度耕地细碎化水平准确度更高;这一情景下亚鱼村平均农户耕地细碎化指数是187.98,该村农户耕作通勤时间成本高;随着农户耕地细碎化程度加剧,农业经营中劳动力投入、资本投入和作物产值呈不同程度的下降趋势,其中资本投入中,耕地细碎化对省工性投入的影响最为显著;山区农业人口乡城迁移背景下农村细碎的耕地资源促使农户加快退出农业生产,导致耕地低效利用,甚至撂荒。  相似文献   

洛南任家滩—荞麦山正长斑岩成因及其对古元古代晚期裂解的指示——岩石化学及锆石U- Pb年龄和Lu—Hf同位素特征     

李毅  李佐臣  赵端昌  赵鹏彬  吕军利  张亚峰 《地质论评》2024,70(1):83-101

华北克拉通南缘的陕西洛南—河南豫西地区出露一系列形成于1. 8~1. 6 Ga的碱性岩,对这些碱性岩的研究有助于提高对华北克拉通南缘古元古代构造环境的认识。笔者等选取陕西省洛南县任家滩—荞麦山一带碱性侵入体进行系统的岩石学、LA- ICP- MS锆石U- Pb年代学、Lu—Hf同位素分析和岩石地球化学研究,讨论了其成因机制和构造背景。研究表明,任家滩—荞麦山岩体的主体岩性为正长斑岩,加权平均年龄为1689±20 Ma（MSWD=0. 12）,表明其侵位时代为古元古代。该岩体富碱（Na2O+K2O=7. 95% ~ 9. 5%）,高钾（K2O=4. 67% ~ 8. 51%）;稀土元素总量较高（496. 15×10-6 ~ 650. 16×10-6,平均543. 06×10-6）,轻、重稀土元素分馏比较明显,轻稀土元素相对富集（LREE=454×10-6 ~ 605×10-6）,重稀土元素亏损（HREE=39. 3×10-6 ~ 45. 6×10-6）,具有弱负铕异常;K、Rb、Ba、Th富集,Nb、Ta、P、Ti亏损,并且具有明显的Sr负异常。εHf（t）值<0,TDM1值为2038 ~ 2218 Ma,TDM2值为2250 ~ 2516 Ma,说明岩浆源区物质与富集地幔有关或受到过地壳物质的混染。因此,任家滩—荞麦山岩体是由地幔玄武质岩浆与地壳基底太华杂岩形成的中酸性花岗质岩浆混合后形成的熔体,经强烈的结晶分异作用形成的,其形成于陆内裂谷的构造环境,是华北克拉通南缘对哥伦比亚超大陆裂解事件的响应。  相似文献   

Land Fragmentation and Spatial Control in the Nazareth Metropolitan Area*     

Ghazi Falah 《The Professional geographer》1992,44(1):30-44

This study demonstrates the linkage between national policy and its spatial expression at the local level. The Palestinian-Israeli conflict is shown to have significance within local government jurisdiction areas, manifested here through the ethnic dichotomization within the Nazareth conurbation in northern Israel. Government policy, both at the national and local levels, is responsible for uneven development between the Jewish and Arab municipalities. Land fragmentation and patterns of spatial control function to constrain and stunt urban growth and development in Arab Nazareth and the neighboring Arab urbanized villages.  相似文献   

含两组结构面的动光弹模型试验研究     

陈庆寿  何思为 《地球科学》1992,17(4):471-476,T001

  相似文献   

Ironies of Consociation: Forest and Natural Resource Governance in Post-War Bosnia and Herzegovina     

Aaron Vlasak 《社会与自然资源》2018,31(5):599-614

ABSTRACT

The nation of Bosnia and Herzegovina (BiH), on southeastern Europe’s Balkan Peninsula, is a unique product of international peace building based on a consociational model of ethnic power sharing. Organized around protection of “vital interests” of its constituent ethnic communities, the BiH state is radically decentralized. In forest administration, national government is practically nonexistent; multiple substate entities including cantons and municipalities operate as autonomous, self-governing units. This paper finds that the politics of accommodation, ironically couched in the language of rights, creates conditions of illiberal dissociation which block consensual natural resource governance. Conservation policies which require political compromise, thus, face a challenge in BiH’s illiberal consociation. Through policy analysis and interviews with representatives of key organizations affected by the 2008 Law on Una National Park, this study finds that when policies are implemented at levels of expected cooperation, the resultant needs are to reconcile rifts of interpretation and coordinate competencies vertically among dissociative bureaucracies.  相似文献   

热机碎岩钻进工艺的试验研究     

吴景华  孙友宏  李军 《探矿工程》2008,35(1):9-11

论述了热机碎岩的基本概念、基本原理;阐述了热机碎岩试验的基本方法,试验设备、试验钻头以及试验岩样;对试验数据以及试验工艺参数的关系做了详细的分析;得出了热机碎岩的最佳工艺参数及结论.  相似文献