Thermal utility of desert vegetation for the Egyptian tortoise and its conservation implications     

《Journal of Arid Environments》2013

We examined the monthly shrub use and the thermal utility of the desert shrub, Artemisia monosperma, by the globally endangered Egyptian tortoise, Testudo kleinmanni, in Sinai, Egypt. A. monosperma is a common desert shrub that is often used by the Egyptian tortoise as a refuge. Egyptian tortoises had the highest mean carapace temperature and lowest carapace temperature range during summer months, which coincided with the aestivation period and the Egyptian tortoise's use of larger shrubs. Our results suggest that the thermal characteristics of larger shrubs are important to the microhabitat use of the Egyptian tortoise and likely long-term survival. Larger shrubs were effective as thermal refuges that ameliorated and stabilized micro-climatic variation. Smaller shrubs were not an adequate thermal refuge in the summer because the mean temperature, and its fluctuation range beneath them was too high to offer adequate refuge during aestivation. The tortoises used the smaller shrubs in the fall, winter, and spring seasons for basking, thermoregulation, and concealment and used shrubs with a cover diameter greater than one meter during the aestivation season. The future conservation of the Egyptian tortoise should focus on protecting and restoring existing habitat by maintaining large perennial shrubs for refuge and aestivation sites.  相似文献   

The political ecology playbook for ecosystem restoration: Principles for effective,equitable, and transformative landscapes     

《Global Environmental Change》2021

The urgency of restoring ecosystems to improve human wellbeing and mitigate climate and biodiversity crises is attracting global attention. The UN Decade on Ecosystem Restoration (2021–2030) is a global call to action to support the restoration of degraded ecosystems. And yet, many forest restoration efforts, for instance, have failed to meet restoration goals; indeed, they worsened social precarities and ecological conditions. By merely focusing on symptoms of forest loss and degradation, these interventions have neglected the underlying issues of equity and justice driving forest decline. To address these root causes, thus creating socially just and sustainable solutions, we develop the Political Ecology Playbook for Ecosystem Restoration. We outline a set of ten principles for achieving long-lasting, resilient, and equitable ecosystem restoration. These principles are guided by political ecology, a framework that addresses environmental concerns from a broadly political economic perspective, attending to power, politics, and equity within specific geographic and historical contexts. Drawing on the chain of explanation, this multi-scale, cross-landscapes Playbook aims to produce healthy relationships between people and nature that are ecologically, socially, and economically just – and thus sustainable and resilient – while recognizing the political nature of such relationships. We argue that the Political Ecology Playbook should guide ecosystem restoration worldwide.  相似文献   

鱼类摄食生态研究的理论及方法   总被引：21，自引：1，他引：21  

窦硕增 《海洋与湖沼》1996,27(5):556-561

综合分析了鱼类摄食生态研究的理论，方法及其应用中的诸多问题：胃含物分析法，营养生境及食物重叠，食物链与食物网，营养结构与营养级，摄食器官的形态特征与摄食行为的关系，食物选择以及生理生太因子对鱼类摄食的影响；提出了食物排序的概念、优势度指数Ｄ及其判定公式，并以此比较客观地建立了摄食生态相似的鱼类群落主次食物的划分标准。  相似文献   

营养盐因子对龙须菜和菊花江蓠氮磷吸收速率的影响   总被引：17，自引：0，他引：17  

钱鲁闽  徐永健  王永胜 《台湾海峡》2005,24(4):546-552

本文在实验室条件下,研究了营养盐因子对龙须菜和菊花江蓠N、P吸收速率的 影响,分别对不同氮和磷的浓度、氮磷比及不同化合态氮对这两种藻类氮、磷吸收速 率的影响进行了实验与分析．结果表明:在适宜范围内,两种海藻对氮、磷的吸收速率 随介质中氮、磷浓度的增加而增加;不同氮磷对两种海藻N吸收速率的影响不存在 显著差异,但对磷吸收速率的影响非常显著,最高对磷吸收速率在介质的氮磷比为 10:1时;海藻对NH4-N的吸收速率随着NO3-N／NH4-N比的降低而增加,对PO43-P的 吸收速率与对NH4-N的吸收相似,而对NO3-N的吸收速率与对NH4-N的吸收相反．  相似文献   

东海区小黄鱼渔业生物学现状的分析   总被引：15，自引：1，他引：15  

林龙山  程家骅 《中国海洋大学学报(自然科学版)》2004,34(4):565-570

以2001年东海区渔业资源监测调查资料为依据，对小黄鱼的体长、体重、生长、死亡等渔业生物学特征及临界年龄等进行了分析研究。结果表明，目前东海区小黄鱼优势体长组为110～130mm，占41．34％；优势体重组为20～40g，占50．91％；总死亡系数为2．05，自然死亡系数为0．58，捕捞死亡系数为1．47，临界年龄为2．18龄。对照东海区小黄鱼生物学特征的历史状况分析，目前东海区小黄鱼个体小型化、低龄化、性成熟提早现象明显，生物学参数发生较大变化。建议在东海区现行资源状态下，小黄鱼的可捕标准应充分考虑其生物学现状加以科学调整。  相似文献   

深圳大鹏湾表层沉积物碎屑矿物空间分布特征     

黄向青  梁开  刘雄 《海洋湖沼通报》2007,(1):74-82

立足样品测试数据,利用空间分析、空间插值、地质统计以及景观生态学方法,深入分析了深圳大鹏湾表层沉积物碎屑矿物的空间分布特征,并使用球状模型对相应半变异函数进行理论建模。结果表明,碎屑矿物分布的Hurst分维数为0.28～0.97,空间几何分维数为1.03～1.72;Moran Ⅰ型空间自相关系数-0.15～0.53。在此基础上,以等值线分布所包围范围作为划分尺度,以Shannon-Wiener信息指数作为度量,得到的矿物分布所反映出的信息量或者富集程度指数为0.88～1.85。  相似文献   

南沙群岛西南陆架区条尾鲱鲤资源状况研究   总被引：1，自引：0，他引：1  

黄梓荣 《台湾海峡》2006,25(2):273-278

根据2003年南沙群岛西南陆架区春秋两季调查资料,分析南沙群岛西南陆架区条尾鲱鲤的资源现状.结果表明,渔获率有明显的季节变动,秋季（1.76kg/h）高于春季（0.08kg/h）,春季密集分布于91～100m水深,秋季密集分布于71～80m水深.其群体组成也有季节差异,春季的平均体长、平均体重大于秋季,春季优势体长组为101～110mm,秋季优势体长组为91～100mm,渔获中不足1龄鱼占多数,其资源密度及现存资源量分别为12.02kg/km^2 和880.82t,现存资源量只有原始资源量的54.92%,该鱼种资源已接近衰退状态.文中并讨论合理利用该资源的措施.  相似文献   

The Effect of Human Exclusion on the Population Structure of Key-Hole Limpets Fissurella crassa and F. limbata on the Coast of Central Chile     

Doris  Oliva Juan Carlos  Castilla 《Marine Ecology》1986,7(3):201-217

Abstract. We describe the basic ecology of two key-hole limpets, Fissurella crassa and Fissurella limbata , which are heavily harvested by coastal shellfishermen (mariscadores) at the rocky intertidal of central Chile. The ecological role of human predation on these species was assessed. Anthropic exclusion from a stretch of the rocky intertidal at Las Cruces (non-harvested area) for about two and a half years resulted in changes of the densities and size distributions of these fissurelid species as compared to populations in control zones (harvested area). Differential human predation generates, on key-hole limpets, responses of different intensities related to the accessibility of man to the mesohabitats (sheltered platforms, exposed platforms and vertical walls) and fringes of the intertidal (mid-low intertidal and Lessonia nigrescens fringe). Thus, size distributions and mean densities of both fissurelids differ widely between the harvested and non-harvested areas on both platform habitats but not on vertical walls. In the mid-low intertidal fringe, differences are greater than in the less accessible L. nigrescens intertidal fringe. Moreover, we discuss the way in which other species, directly harvested by mariscadores (i. e., the mollusc Concholepas concholepas) can affect the keyhole limpet populations of central Chile rocky shores. Finally, we highlight the ecological role of these limpets on the dynamics of intertidal ecosystems and how they can modify community landscape.  相似文献   

Biokarst on Limestone Coasts, Morphogenesis and Sediment Production   总被引：3，自引：0，他引：3  

Jürgen  Schneider Horst  Torunski 《Marine Ecology》1983,4(1):45-63

Abstract. Biokarst-forms on limestone coasts are developed and arranged according to the bionomic zonation. The development of biokarst is the result of bioerosion, a synergistic effect of biological corrosion by endoliths and biological abrasion by grazers.
The cumulative effect of biogenic carbonate destruction leads to coastal destruction with a resulting highly profiled morphology on the limestone surfaces along the coastal profile. Under the influence of environmental factors a zonation of organisms develops which brings in turn a zonation of erosion rates (0.1-1.1 mm a^-1) resulting in biokarst-forms such as rock holes, rock pools and notches.
Products of bioerosion on limestone coasts are dissolved carbonate (by biological corrosion, 10–30% of the decomposed limestone) and particulate carbonate (by biological abrasion, 70–90% of the decomposed limestone) both of which contribute directly or indirectly to nearshore sedimentation. Size and shape of the bioerosional grains are determined by the boring pattern of the endoliths. The fine-grained sediments (maximum within the fraction 20–63 μm) contribute 3–25 % to the nearshore sediments.
Drastic changes in the biological zonation (like the mass invasion of the sea urchin Paracentrotus lividus in the Northern Adriatic since 1972 which eliminated nearly the entire macrophyte zone) due to unknown factors or pollution can have a profound effect on the bioerosion rates, altering them by as much as a factor of ten.  相似文献   

Fish preference by the harbour seal (Phoca vitulina), with implications for the control of damage to fishing gear     

Lunneryd  S. G. 《ICES Journal of Marine Science》2001,58(4):824-829

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