HOME GARDENS IN AMAZONIAN PERU: DIVERSITY AND EXCHANGE OF PLANTING MATERIAL*     

NATALIE BAN  OLIVER T. COOMES 《Geographical review》2004,94(3):348-367

ABSTRACT. This article examines how peasant farmers build and maintain agrobiodiversity in home gardens found in two traditional peasant communities along the Marañón River in the Peruvian Amazon. Data were gathered through household and garden surveys as well as in‐depth interviews with garden tenders in an upland mixed agricultural village and a lowland fishing village. Substantial variations in cultivated plant diversity were encountered in gardens between and within the villages, which are found to be related to differential exchange of seeds, cuttings, suckers, and other planting material as well as to specific garden and household characteristics. Planting material flows along multiple pathways—from gift giving and purchase to inheritance and scavenging—to the gardens, reflecting a complex and often extensive network of exchange that enables the establishment and maintenance of home garden plant diversity in seemingly isolated and small communities. Further research is needed to identify broader geographical and sociocultural patterns of agrobiodiversity in Amazonia.  相似文献   

分层施肥对小麦植株含N量的影响     

徐佩  艾应伟  张先婉 《山地学报》1997,(3)

对平作表层(1～2cm)土层施肥与垄作表层(1～2cm)、中层(25cm)、底层(45cm)土层施肥时的小麦不同生育时期各器官含N量的研究结果表明:无论是垄作还是平作表层施肥,小麦从三叶期到拔节期根、叶的含N量由高到低;而垄作中层和底层施肥却由低到高。三叶期时根、叶含N量以表层施肥>中层施肥>底层施肥。而表层施肥的垄作与平作间对比,则根叶的含N量无显著差异,三叶期以后小麦根、茎、叶、粒、壳的含N量影响不大。另外,垄作底层,中层施肥比表层施肥显著增加了小麦产量。  相似文献   

无人驾驶飞机航测数据的葡萄种植面积估算方法     

陈爱京  肖继东  李良序 《沙漠与绿洲气象(新疆气象)》2006,29(2):17-19

以无人驾驶飞机拍摄的影像为数据源,通过非监督、监督和人机交互式分类方法分别对小区域葡萄种植面积进行了估算,并结合实际调查数据,对比了三种分类方法在面积估算中的精度。  相似文献   

海南省的环境与可持续发展问题探析     

杨冠雄 《海洋地质前沿》2002,18(3):10-13

海南岛是中国唯一一个全省位处热带的省份，有得天独厚的环境和资源。到目前为止，海南省的环境一直处于良好的状态，大气环境各项指标基本上符合国家一级标准，全省河流和水库中的水有80%符合国家地面水环境质量Ⅱ类及以上标准。但是，对海南省的环境也不应当地高估计，建省前后的开发过程出现了许多生态和环境问题，例如林业砍伐、橡胶垦殖等。不能只讲开发，不讲保护或是因为开发对环境有影响就不进行开发，要坚持可持续发展的战略，妥善解决实现可持续发展中遇到的各种具体问题，真正把海南省规划建设好。  相似文献   

Temporal changes and spatial variation of soil oxygen consumption, nitrification and denitrification rates in a tidal salt marsh of the Lagoon of Venice, Italy   总被引：4，自引：0，他引：4  

P. G. Eriksson  J. M. Svensson  G. M. Carrer 《Estuarine, Coastal and Shelf Science》2003,58(4):861-871

The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. ¹⁵N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen.  相似文献   

新疆昌吉绿洲耕地适宜规模研究     

李婧昕  张红旗 《地理研究》2021,40(3):613-626

干旱区内耕地急剧扩张导致水资源严重超载,进而引发一系列生态问题,因此对干旱区绿洲耕地适宜规模进行科学评估,将为干旱区农业可持续发展与生态保护提供重要参考。本文以水资源为约束条件,选择2000年、2005年、2010年、2015年和2018年5个研究时段,分别测算了适宜当地社会经济发展和生态环境需求的“三生”用水量;并基于绿洲水热平衡原理,耦合作物种植结构、不同生长期内的作物系数以及灌溉保障率、耕地覆膜等因素,构建了干旱区耕地水热平衡估算模型,探讨了不同情景下新疆昌吉州耕地适宜规模及其超载程度。结果表明,5个时段中,临界耕地适宜规模情景下的种植业可用水量由2000年的31.75亿m3波动下降至2018年的24.83亿m3,而最佳耕地适宜规模情景下则由27.63亿m3波动下降至21.10亿m3。棉花和小麦在当地种植业结构中占比之和由43.58%提高到2018年的59.08%,两种作物的低耗水特性使其种植占比的提高有利于当地种植业向耕地规模扩张的方向演进。各时段中,保障充分生态用水的最佳耕地适宜规模在28.93万~48.97万hm²间波动,而保障最低生态用水的临界耕地适宜规模在42.63万~67.83万hm²间波动。虽然两种用水情景下的适宜耕地规模波动变化,但耕地面积超载程度始终呈上升趋势,超载程度分别由2000年处于不超载水平的-55.15%和-39.41%提高到2018年的接近于严重超载级别的19.92%和远超严重超载级别的71.37%,表明当地耕地规模已明显呈现过度开发的趋势。  相似文献   

基于CR-BDI模型的农户作物种植行为模拟——以陕西省米脂县姜兴庄为例   总被引：1，自引：1，他引：0  

王艳妮  陈海  宋世雄  梅亚军  温馨 《地理科学进展》2016,35(10):1258-1268

运用模拟平台模拟农户土地利用行为,对揭示农户土地利用变化机制和调整土地利用决策具有重要意义。本文选择生态脆弱区一乡一业、一村一品典型村陕西省米脂县姜兴庄为例,以信念—愿望—意图模型(BDI)为基础,构建有限理性能力与资源(CR-BDI)模型。基于NetLogo平台对CR-BDI模型和传统BDI模型的模拟情况进行对比分析,结果表明：①CR-BDI模型更适于微观尺度农户土地利用决策研究。2014年该模型面积失误率为6.78%,比传统BDI模型低8.48%,空间准确率比传统BDI模型高10.10%,2015年CR-BDI模型和传统BDI模型的整体空间正确率分别为78.8%和69.2%;②CR指数有利于体现农户的有限理性,与实际种植决策较为符合;③利用NetLogo平台有利于直观再现农户土地利用行为,揭示土地利用变化的微观机理,可作为研究土地利用变化互动机理的良好平台。  相似文献   

种植条件下降雨灌溉入渗试验研究   总被引：2，自引：0，他引：2  

宋亚新  张发旺  荆恩春 《地球学报》2008,29(4):510-516

基于清水河平原头营和黑城试验场降雨(灌溉)入渗过程土壤水分运移观测试验数据的分析研究,笔者应用能量观点描述了包气带水分运移的分带性、降雨(灌溉)入渗补给地下水的水分条件和地下水入渗补给过程的基本特征。应用蒸散量模型、土壤水分通量模型,计算了作物生长期的蒸发蒸腾量、土壤贮水量的变化量、400cm深度处的土壤水分渗漏量及渗漏系数。从多年的角度分析了深层土壤水分渗漏量、渗漏系数与地下水入渗补给量和补给系数的关系。它对分析降雨(灌溉)入渗对地下水的补给过程和定量分析地下水入渗补给量、入渗补给系数具有重要价值。  相似文献   

Cluster planting impact on cotton growth,yield and biomass accumulation in an arid region oasis     

Ting Ting Xie  Pei Xi Su  Wen Zhi Zhao  Li Shan Shan 《寒旱区科学》2018,10(3):271-278

The cluster planting pattern(3 plants per hole) for cotton(Gossypium hirsutum L.) may increase economic yield over those of the traditional planting pattern(1 plant per hole) in arid regions of China. This increase in yield depends on either increased biomass production or greater partitioning to fruit. This study was conducted to determine whether differences in biomass accumulation or partitioning to reproductive growth contributed to higher yield in the cluster planting pattern compared with the traditional one. Growth parameters, biomass accumulation, crop growth rate and partitioning between cluster planting pattern and traditional planting pattern was compared in northwest of China. The biomass production and partitioning in cluster planting plot was higher than in traditional planting one. Biomass accumulation was faster early in the clustered treatment, and it was also higher at harvest time. Total dry matter production per unit area was significantly higher than in the traditional planting. On a per plant basis, dry matter accumulation was faster and total biomass production was significantly higher in the cluster planting pattern. Numbers of sympodia and boll sizes were also larger, indicating that facilitation among plants was promoting crop yield. The increase in yield in the cluster planting treatment occurred through increased partitioning of dry matter to fruits than in the traditional planting pattern, resulting in more bolls and increased lint yield in arid regions.  相似文献   

人工草地种植模式对沙化土壤团聚体及有机质含量的影响   总被引：1，自引：0，他引：1  

蔺芳  刘晓静  张家洋 《中国沙漠》2018,38(6):1219-1229

通过连续6年定位试验,研究了紫花苜蓿（Medicago sativa）单播、多年生黑麦草（Lolium perenne）单播、紫花苜蓿/多年生黑麦草混播3种种植模式对豫北地区土壤团聚体及其有机碳和土壤有机质的影响,并利用分形维数对土壤团聚体特性进行了量化研究。结果表明：沙化裸地和3种种植模式下土壤机械稳定性团聚体以5~3 mm和3~2 mm粒径为主,土壤水稳性团聚体以<0.25 mm粒径为主;与沙化裸地相比,3种种植模式下5~3 mm和3~2 mm 粒径土壤机械稳定性团聚体含量显著增加,而土壤水稳性团聚体的变化主要表现为<0.25 mm粒径显著减少,3~2 mm和2~0.5 mm粒径显著增加,同时≥2 mm粒径的土壤机械稳定性和水稳性团聚体有机碳含量明显增加;与沙化裸地相比,3种种植模式下土壤有机质含量均不同程度地增加,紫花苜蓿/多年生黑麦草混播 > 紫花苜蓿单播 > 多年生黑麦草单播,且随土层的加深而降低,呈现表聚性特征;无论机械稳定性还是水稳性团聚体,土壤质量分形维数（D_m）沙化裸地 > 多年生黑麦草单播 > 紫花苜蓿单播 > 紫花苜蓿/多年生黑麦草混播;5~3 mm和3~2 mm粒径的土壤机械稳定性和水稳性团聚体与有机碳含量极显著正相关（P<0.01）,与土壤有机质含量极显著相关（P<0.01）。相对于沙化裸地,豫北地区人工草地建植6年后能够有效改善土壤团聚体特性,优化土壤主要理化性状,其中又以紫花苜蓿/多年生黑麦草混播为最佳的种植模式。  相似文献