Ecological Benefits of Compound Ridge Culture in Hillside Orchard in the Three Gorge Reservoir Area

Based on contour tillage of wide ridge and furrow covering and agro-forestry, this paper sets up a compound ridge culture mode in hillside orchards and introduces a long-term observation to the mode＇s effects on ecological benefits of water and soil conservation. A five-year study shows that compound ridge culture in hillside orchards is effective in water and soil conservation, especially in reducing soil erosion. Compared with the traditional management modes of orchards, compound ridge culture has reduced runoff amount by 41.96%-57.96%, soil erosion amount by 55.47%-67.75%. Compound ridge culture also brings an obvious reduction of soil nutrient loss and of non-point source pollution, which is of great importance for keeping and increasing the productivity of hillside orchards in the Three Gorge Reservoir Area.

Seasonal Variations of Soil Enzyme Activity on Rocky Hillsides Continuously Planted with Vitis heyneana Roem.et Schult

[Objectives]This study was conducted to investigate the effects of Vitis heyneana cultivation on rocky hillsides on the variation of soil fertility,so as to provide theoretical support for economic development and the control of rocky desertification in the Dashi mountainous area.[Methods]Taking V.heyneana planting base in Luocheng County,Hechi City,Guangxi Province as the research object,the methods of field investigation,regular sampling and experimental analysis were used to analyze seasonal variations of soil urease,sucrase and soil alkaline phosphatase activity of 15 different sample plots surveyed,and their correlation with soil physical and chemical properties was analyzed.[Results]①In general,sucrase,urease and alkaline phosphatase were lower in summer and autumn,and higher in spring and winter,and the performance of the activity of the three enzymes was inconsistent.Among them,the activity of sucrase was in order of spring>autumn>summer>winter,and the activity of urease and alkaline phosphatase showed an order of winter>spring>summer>autumn.②The seasonal variations of soil fertility in different sample plots were affected by various factors such as human disturbance,climate change,vegetation coverage,topography and landforms,cultivation and management measures,and although the change laws in different sample plots were different,the seasonal differences in soil fertility in the same place were extremely significant.③If the influence of artificial fertilization factors is excluded,the planting of V.heyneana on rocky hillsides will cause a significant decrease in soil enzyme activity,that is,a significant decrease in soil fertility.[Conclusions]Related issues such as the effects of planting V.heyneana on the variation of soil fertility in rocky hillsides should arouse necessary attention of management departments and producers.

Effect of Closing Hillsides Afforestation on Population Diversity

A logaritmic series distribution model was used to evaluate the index of population diversity (α value) inQuercus mongolica forest in Zhanguangcai Mountains, Heilongjiang, Northeastern China. The α value went up from 1.07 to 4.46–6.98, after closing hillsides for 20 years. The spatial distribution of the α value was calculated among the hill slopes. The results were as follows: middle of hill>bottom of hill>top of hill.

Nonlinear numerical assessment of the seismic response of hillside RC buildings

Major damage has been reported in hilly areas after major earthquakes,primarily because of two special conditions:the variation in the seismic ground motion due to the inclined ground surface and the irregularities caused by a stepped base level in the structure.The aim of this study is to evaluate possible differences in the responses of Chilean hillside buildings through numerical linear-elastic and nonlinear analyses.In the first step,a set of response-spectrum analyses were performed on four simplified 2D structures with mean base inclination angles of 0°,15°,30°,and 45°.The structures were designed to comply with Chilean seismic codes and standards,and the primary response parameters were compared.To assess the seismic performance of the buildings,nonlinear static(pushover)and dynamic(time-history)analyses were performed with SeismoStruct software.Pushover analyses were used to compare the nonlinear response at the maximum roof displacement and the damage patterns.Time-history analyses were performed to assess the nonlinear dynamic response of the structures subjected to seismic ground motions modified by topographic effects.To consider the topographic modification,acceleration records were obtained from numerical models of soil,which were calculated using the rock acceleration record of the Mw 8.01985 Chilean earthquake.Minor differences in the structure responses(roof displacements and maximum element forces and moments)were caused by the topographic effects in the seismic input motion,with the highly predominant ones being the differences caused by the step-back configuration at the base of the structures.High concentrations of shear forces in short walls were observed,corresponding to the walls located in the upper zone of the foundation system.The response of the structures with higher angles was observed to be more prone to fragile failures due to the accumulation of shear forces.Even though hillside buildings gain stiffness in the lower stories,resulting in lower design roof displacement,maximum roof displacements for nonlinear time-history analyses remained very close for all the models that were primarily affected by the drifts of the lower stories.Additionally,vertical parasitic accelerations were considered for half the time-history analyses performed here.The vertical component seems to considerably modify the axial load levels in the shear walls on all stories.

岩溶山区坡面一孔多层地下水监测试验及科学意义

钻孔是揭露含水层结构和开展地下水监测的重要载体。在场地地下水监测中,不分层的丛式钻孔存在成本高、代表性不全等缺陷。“一孔多层”分层监测对水头或溶质分布的区分度高,在孔隙和裂隙含水层应用广泛,但岩溶介质因结构复杂,极少有案例研究。文章对丫吉试验场西坡径流小区的一个钻孔(ZK6)进行分层并开展监测。依据钻孔岩芯编录资料、抽水试验以及水化学与温度测孔的结果,判断岩溶发育的特征,确定将ZK6孔划分为四层,实施了钻孔封隔。对四个层位的水文观测发现,四个层位的水位动态对降雨的响应有较大差异。其中,第一层一个水文年中无水和充水状态时长分别占79%和21%,说明该层的岩溶介质处于充水和无水交替,且更多时间处于无水状态;第二层水位响应滞后明显;第三层和第四层水头差异表现出地下水排泄区的水头垂直分布特征。ZK6孔四个层位的水化学存在差异,表明岩溶介质结构的差异不仅影响了水文过程也影响水化学特征。第四层的电导率基本稳定在450μS·cm^(-1),而第二层因表层元素积累和水更新速率慢,电导率是第四层的2倍,第一层电导率的剧烈变化则反映表层岩溶带受到降雨补给影响最为强烈。综合钻孔分层的水文和水化学特征,认为第一至第四层分别代表表层岩溶带、裂隙基质带、上部饱水带和下部饱水带。岩溶山坡的“一孔多层”分层技术难度大,但一旦实现不仅可以认识岩溶垂向分带的水动力机制,也为地下水分层开发利用技术突破提供了可能。

建造于山坡位置的建筑地下室渗水检测鉴定分析

通过现场调查及检测鉴定,对两栋建造于山坡位置的既有建筑地下室漏水原因进行分析,综合判断地下室积水来源于大气降水经土壤渗透在建筑物基础外围岩石坑形成的局部积水槽积水,并分析了地下室漏水对地下室承重结构构件安全性的影响。总结出这类建筑地下室渗漏原因,为该类新建建筑地下室的防水设计或该类既有已存在漏水现象的建筑改造提供有实际意义的借鉴价值。

免炼山免挖穴简力定植对桉树人工林根系和生长的影响

传统的炼山、大穴造林方式易引桉树人工林起水土流失、地力下降等一系列问题,免炼山、免挖穴、简力定植可能是解决上述问题的重要手段。文章以尾巨桉为研究对象,布置了桉树免炼山、免挖穴、简力定植方式并以大穴造林为对照,探讨两种方式对桉树人工林根系与蓄积量的影响。结果表明:造林5年后两种造林方式桉树人工林的根系主要分布范围在土层0~70 cm且根系数量多分布于土层20~50 cm,两种造林方式间差异不显著。造林后前2年,简力定植区的桉树胸径、树高与蓄积量略低于对照区但差异不显著;造林3年后逐渐反超,至第五年简力定植区桉树胸径、树高、蓄积量相较于对照区分别增长4.90%、5.13%、15.00%。简力定植造林未对林木蓄积量产生不良影响,反而提高了林木的生长量,对解决桉树人工林地力下降等问题具有较好的效果。

丘陵山地拖拉机折腰壳体仿真分析

针对丘陵山地拖拉机底盘受载工况恶劣,折扭壳体强度不足造成易断裂问题,在颠簸、斜坡和转向3种工况下运用Nastran和Hypermesh联合建立有限仿真分析模型进行校核计算。根据仿真分析结果判断壳体结构的合理性,通过改变折腰壳体结构设计使强度安全系数有效提升,经过3种工况的折腰壳体强度专项试验验证,并通过超声波仪器对壳体薄弱部位进行物理探伤,壳体无损害现象。试验结果验证了折腰壳体理论设计和仿真分析的可靠性及可行性。

欧黑青杨和小黑杨在山地栽培的对比研究

对栽植在四平市铁东区山地不同坡位的21年生小黑杨和欧黑青杨进行材积生长对比试验。结果表明:品种杨对水分的需要更重于对土壤养分的需要,其人工林抚育浇水重于施肥;品种杨通常适宜在平地和山坡下腹地栽培,而对于速生的欧黑青杨适于在平地和山坡中腹、下腹部位栽培。

坡地果园间种不同绿肥的效应研究

为改良坡地果园土壤,开辟果园有机肥源,进行了果园间种白花草、三叶草、芒草并压青的定位测定试验。结果表明,间种这3种草可明显提高果园土壤的pH值,增加土壤有机质,培肥土壤,提高土壤碱解氮、速效磷和速效钾的含量。与无覆盖处理相比,果园间种绿肥pH值提高0.5～0.7个单位,有机质含量提高1.1～3.3 g/kg,土壤碱解氮、速效磷(P2O5)和速效钾(K2O)分别提高2.5～7.1、0.8～2.1、5.8～12.2 mg/kg。同时还可改善坡地果园生态小气候、稳定地温,不同绿肥覆盖显著降低地表温度3.9～7.6℃,进而调节了果树生长环境,有利于果树生长。果园间种绿肥与无覆盖处理相比,桃单果重平均增加7.7%,单株产量平均增加12.5%,差异显著。

黄土高原坡地密植枣园土壤质地与肥力状况分析

采用田间取样与实验室分析相结合的方法,研究了黄土高原坡地密植枣园土壤质地与肥力状况。结果表明,坡地枣园土壤肥力低,氮、磷严重缺乏,钾相对丰富,土壤属于砂壤土,通气性强,保肥、保水性差。0-60 cm土壤有机质含量为1.687-5.002 mg/kg;全氮为0.072-0.316 g/kg;硝酸盐为2.325-16.846 g/kg;铵态氮为1.187-2.146 g/kg,速效磷为0.270-2.480 mg/kg,速效钾为51.9-169.1 mg/kg,并且含量均随剖面向下减少。颗粒组成大部分为粉砂粒,含量一般在65.75%-68.98%;随有机质含量升高,0.25-0.05 mm微团聚体数量呈上升趋势,二者为正相关;〈0.05 mm微团聚体含量则逐渐下降,二者呈负相关。黄土高原坡地密植枣园土壤肥力总体水平很低。除了速效钾为中等级外,有机质、全氮、碱解氮、速效磷均为很低等级。

小型山地履带拖拉机爬坡越障性能分析与试验

小型山地履带拖拉机(简称山地拖拉机)在田间行驶时,常遇到台阶、砖头、石块、田埂等障碍,严重影响其通过性及稳定性,进而引发侧滑甚至倾翻等安全问题。为此,选取最难跨越的台阶作为研究对象,对山地拖拉机爬坡越障性能进行研究。首先,对山地拖拉机爬坡时跨越台阶的运动过程进行分析,得到求解最大越障高度的计算公式;然后,基于多体动力学分析软件RecurDyn进行了正交和单因素变量仿真试验,仿真结果表明:越障速度、坡度角和拖拉机质心位置均显著影响山地拖拉机的最大越障高度,增大越障速度和质心支重轮距、减小坡度角和质心高度均可提高山地拖拉机的爬坡越障性能;最后,基于自主设计的山地拖拉机进行了爬坡越障田间试验。结果表明,在速度1.6 km/h、坡度角为0°~15°工况下,试验结果与理论计算及仿真试验结果基本一致,理论计算与仿真试验的最大相对误差分别为5.17%、6.47%;在坡度角大于15°工况下,理论计算与仿真试验最小相对误差分别为13.25%、19.21%。说明所得到的山地拖拉机最大越障高度计算公式及仿真模型在坡度角为0°~15°时有效。

露天边坡与山坡复合体变形灰色预测

边坡变形与破坏是一个复杂的过程,其影响因素众多、且具有不确定性,一般很难用确定的函数式来预测。在丘陵地区进行露天开采,地面变形对周边环境安全影响非常大,从而严重地影响到安全生产。本文应用灰色预测模型对露天开挖边坡与山坡复合体巨型边坡的移动与变形发展趋势进行预测,并对发展趋势进行了分析,以便为后续开采设计与安全生产服务。

黄龙山林区封育油松种群动态研究

对不同封育年限油松种群的高度、径级、年龄结构进行分析,运用马尔可夫转移矩阵预测种群密度动态.结果表明,不同封育年限种群的生长发育明显不同.种群个体高度以2～4 m和6～8 m占优势,胸径以0～2 cm的小径阶和＞20 cm的大径阶占较大比重;在各封育系列中,种群的密度中、大级出现几率较大.在封育45年前,种群的年龄结构中大树所占比例最大;45年后,小树和幼苗则较多,但种群弱小个体大量死亡.本区天然林保护年限最短应确定为45年.

山地酿酒葡萄园土壤理化性质分析

对陕西省渭北高原山地3个不同海拔高度酿酒葡萄园0～60cm土层土壤的理化性质进行了研究。结果表明:各葡萄园土壤pH均在8.0左右,属碱性土壤;土壤有机质和N、P、K等大量元素含量偏低,各种微量元素除了B含量很低以外,其他元素均含量丰富;各葡萄园土壤理化性质差异很大,从整体上看海拔最低点的最好。土壤养分中速效N、P、K含量与黏粒(<0.002mm)含量之间呈显著的正相关,与粉粒(0.002～0.02mm)含量之间呈显著的负相关。

南方丘陵区土地整理的误区及对策探析

通过剖析当前南方丘陵区土地整理普遍存在单纯追求增加耕地数量、固定的整理模式和高品位规划设计、后续效益与市场经济脱节,缺少产业支撑的误区。结合南方丘陵区土地整理的效益目标,提出土地整理应针对南方丘陵区特有的土地生态经济系统,根据其特殊的交通、地质、地形地貌和耕作制度,从提高耕地质量、加强生态环境保护、提高项目后续效益入手,因地制宜进行规划设计。

喀斯特封山育林区土壤种子库研究

对贵州省都匀市喀斯特封山育林区土壤种子库进行了研究，结果表明：都匀喀斯特封山育林区土壤种子库中活力种子丰富，共有18科45属46种。其中草本植物种子占绝对优势，占种子数的81．25％，木本植物只占18．75％。草本以白酒草占绝对优势，为54．54％。8个不同封育年限的样地的种子密度变动于2309—4459粒／m^2。在各个土层中它们的变化具有一定的规律，即随土层的加深，种子数量不断减少。随着封育年限的增加，林分的郁密度加大。土壤种子库中种子数量、种类在相应的时间内不断减小；而在相当长的时间后，种子数量、种类又有所增加。

黑河上游山区植被的空间分布特征及其影响因素

以祁连山区的生态植被为研究对象,应用MOD IS NDVI遥感数据及DEM地形高程数据,定量分析了海拔高度、坡向对植被发育的影响,并对降雨、地温等气候因素对植被生长的影响进行了讨论。结果表明:1)植被指数随高程的增加逐渐增大,在高程3400m处达到峰值,植被发育最好,而后又随着高程的增加逐渐减小;2)在海拔3400m以下,植被指数随着降雨量的增大而增大,随着地表温度的增加而减小;在海拔3400m以上,植被指数则随着降雨量的增加而减小,随着地表温度的增大而增大;3)受太阳辐射的影响,在高程3200m^3600m范围内,坡向为NE0~70o,NW 330~360o之间的区域植被长势最好,这一变化则主要受地温的影响。其它高程范围内,植被长势与坡向关系不明显。

黄土高原山地坡度对退耕农田生态系统自然植被演替初期的影响

黄土高原丘陵沟壑区是我国西部干旱半干旱生境下的典型生态脆弱地区,是国家实施退耕还林还草、再造秀美山川工程的重点区域,其中山地坡度作为一个重要的生态因子,探讨其对黄土高原生态恢复的影响具有重要意义。以封育5年的退耕农田为目标,探讨山地坡度对黄土高原受损生态系统恢复和保育的影响,结果表明:1)山地坡度的增加显著降低了阳坡植物群落的物种多样性(P<0.01);而对阴坡植物群落物种多样性没有显著影响(P>0.05)。2)山地坡度对阴坡群落的均匀度指数影响显著(P<0.05);而对阳坡群落的丰富度影响较大,呈现先增加后降低的趋势。3)坡度对阳坡植物群落的生物量影响显著(P<0.05)。分析表明,山地坡度对黄土高原丘陵沟壑区退耕农田植物群落演替初期的自然恢复具有显著影响:在坡度<30°的条件下,植被群落自然恢复效果较好;而对>30°的退耕山地,则需要人工辅助措施的促进,是开展退耕封育的重点区域。

基于OWA的低丘缓坡建设开发适宜性评价——以云南大理白族自治州为例

山区城市在城镇化、粮食安全、生态保护的多重要求下,有必要探索将基本农田以外的低丘缓坡山地开发为建设用地的可行性和限制性。研究选取涵盖景观风险和灾害风险的共12个空间化指标,基于有序加权平均(ordered weighted averaging,OWA)方法,以大理白族自治州为例进行低丘缓坡区域建设开发适宜性评价。通过设置不同位序权重表征评价者偏好,结果表明:在指标风险程度的可信度较高的情况下,农用地、城镇、断裂带、河流等高风险指标权重被加大,空间特征明显;在指标风险程度的可信度较低的情况下,评价结果的空间均质性增强。通过模拟城镇建设导向、维持现有政策、风险控制导向3种适宜性分区情景,得出在城镇建设导向下应优先开发中小城镇,在风险控制导向下应优先保证大城市合理扩展。评价结果可以描述在城市的不同发展阶段如何构建政策权衡后的城镇化空间格局,满足了不同决策思路下的建设用地开发布局需求。