旱地春玉米倒秆免耕两元带状覆盖膜侧种植技术与应用前景

为了将有限的自然降水最大限度地蓄积、保存于土壤之中,并尽可能地提高其利用效率,连续多年采用田间试验与大面积示范相结合的方法,集成创新研究的"旱地春玉米倒秆免耕两元带状覆盖膜侧种植技术",融"冬闲期倒秆覆盖免耕"与"生育期两元带状覆盖膜侧种植"两项技术的优点于一体,能综合调节旱作农田的水、肥、气、热条件,最大限度地利用自然降水,因而旱地春玉米生长稳健茁壮,增产增收效果显著,水分利用率也达最高。同时,该技术并具有增加土壤有机质,提高土壤潜在肥力和控制水土流失,减轻沙尘飞扬,改善生态环境,促进农业可持续发展的效果。     

基于VB的旱作作物种植结构决策支持系统开发

以Jensen水分生产函数为基础,运用多目标规划的方法,建立了旱作条件下小麦、玉米、大豆、马铃薯、高粱等作物种植结构优化系统,并编制了可视化应用程序。输入多年降雨资料、日照时数、每日最高最低温度、每日风速等基本气象资料以及相关的土壤、作物参数,就可优化出研究地区主要作物种植比例和结构,操作简单,具有实用性。以山西晋中地区为例进行应用,系统根据多年的降雨资料预测出不同水文年型下每种作物的单产,在此基础上对种植结构进行了优化,并与实际结果比较证明其可靠性,从而对作物种植结构进行优化和指导,使粮食产量、经济效益、水分利用达到协调统一。     

Effects of soil moisture on cotton root length density and yield under drip irrigation with plastic mulch in Aksu Oasis farmland

Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spatial distributions of root length density of cotton under various water treatments were basically similar. Horizontally, both root length densities of cotton in wide and narrow rows were similar, and higher than that between mulches. Vertically, root length density of cotton decreased with increasing soil depth. The distribution of root length density is different under different irrigation treatments. In conditions of over-irrigation, the root length density of cotton between mulches would increase. However, it would decrease in both the wide rows and narrow rows. The mean root length density of cotton increased with increasing irrigation water. Water stress caused the root length density to increase in lower soil layers. There is a significant correlation between root length density and yields of cotton at the flower-boll and wadding stages. The regression between irrigation amount and yield of cotton can be expressed as y = -0.0026x2+18.015x-24845 (R2 = 0.959). It showed that the irrigation volume of 3,464.4 m3/hm2 led to op-timal root length density. The yield of cotton was 6,360 .8 kg/hm2 under that amount of irrigation.     

大兴安岭白桦天然林改培为速生丰产林技术及其效益分析

对白桦天然林改培速生丰产林试验地的调查数据进行分析,确定了白桦天然幼、中龄林进行3次抚育采伐的时间,分析了透光抚育和生长抚育的效果,明确了白桦天然林不同林龄时的最佳抚育强度以及不同龄级的最佳经营密度.分别对人工培育白桦林和对本区白桦天然林进行人工抚育的经济效益进行了分析.     

云南植胶先行者泰国归侨钱仿周、李宗周----兴办暹华胶园始末纪实

<正>云南天然橡胶种植始于20世纪初。盈江县土司刀安仁先生于1904年从新加坡引进橡胶苗8 000株,种植在新城凤凰山东南坡上,至今已有100多年,凤凰山上仍幸存两株老胶树可作历史的见证。他是云南乃至我国种植天然橡胶的先行者。     

园林工程绿化种植施工组织管理探析——以黄河风景名胜区一线绿化种植施工管理为例

园林工程中的种植工程是介入生物学、生态学的范畴,以工程为基础运用于风景园林建设中。该研究围绕园林工程的施工组织管理工艺流程的内涵与外延,依据黄河风景名胜区的一线绿化种植施工管理为主线。通过现场的组织管理,分析、归纳出园林工程如何在组织管理中综合发挥出园林的生态效益、社会效益和经济效益的统一,为整个园林绿化施工组织管理提供切实可行的方案。     

小桐子育苗密度研究

[目的]获得小桐子最佳的育苗密度。[方法]通过对在不同育苗密度下小桐子高生长、地径和分枝量的分析获得小桐子育苗的最佳密度。[结果]试验发现15cm×20cm为小桐子的最佳育苗密度,在最佳育苗密度下,小桐子平均每公顷出苗250005株,平均每公顷出优质苗160710株,出圃率为64.30%,平均育苗每株的成本为0.18元。     

Landslide densities associated with rainfall,stand age,and topography on forested landscapes,southwestern Washington,USA

Elevated landslide rates in forested landscapes can adversely impact aquatic habitat and water quality and remove and/or degrade soil resources required for forest regeneration. As a result, understanding the associations between management actions, natural factors, and landslide rates is important information needed for land managers. An unusual and powerful storm in early December, 2007, caused record flooding and thousands of landslides across southwest Washington and northwest Oregon, USA, and provided a rare opportunity to examine the effects of both natural factors and forest management practices on landslide density. Landslide inventory data were collected from both aerial photos and systematic field surveys to provide a broad survey database that was used to develop estimates of landslide density and to examine associations between landslide density, precipitation, topography, and forest stand age across a 152,000 ha forested landscape in the Willapa Hills, Washington. We estimated the probability of detecting landslides on aerial photos for six strata defined by forest stand age and a broad range of rainfall intensity, expressed as percent of the 100-year, 24-h, maximum rainfall. Key findings are that landslide detection probability decreased with increasing stand age, but was similar across rainfall intensities. The overall fraction of field-detected landslides that were not detected on 1:12,000-scale aerial photos was 39%. Very few landslides occurred in the 0–100% of 100-year rainfall category, regardless of stand age or slope gradient class. At higher rainfall intensities, significantly higher landslide densities occurred on steep slopes (>70% gradient) compared to lower gradient slopes, as expected. Above ∼150% of 100-year rainfall, the density of landslides was ∼2–3 times larger in the 0–5 and 6–10 year stand age categories than in the 11–20, 21–30, 31–40, and 41+ categories. The effect of stand age was strongest at the highest rainfall intensities. Our results demonstrate that ground-based landslide inventory data are required in order to correct for detection bias from aerial photos, develop reasonable estimates of landslide density across environmental gradients such as rainfall magnitude and topography, and make unbiased interpretations of relationships between forest management associations and landslide occurrence.     

Measuring ecologically important quantities at relevant operational scales: An example using the dusky flycatcher in selectively logged forests in Idaho

Effective management of forest wildlife requires information about habitat features that can be altered by operations, if those habitat features promote reproductive success and survival, and if changes in organism density influence reproductive success and survival. Habitat selection studies often provide the first type of information, although relatively few studies examine how different selection decisions or densities of organisms influence fitness measures or measure habitat features at relevant operational scales. We examined patterns of habitat selection and estimated how habitat use, territory size, and conspecific density were associated with territory success (probability of a territory producing one or more fledglings) for the dusky flycatcher in 2002–2003 on eight study plots in managed grand fir (Abies concolor) forests in Idaho, USA. Flycatchers selected territories with greater cover of deciduous vegetation in two different height strata (1–2 and 3–4 m) and reduced cover of conifers less than 4 cm dbh compared to what was available. While flycatchers selected habitat characteristics at the territory scale, model selection results did not support any associations between vegetation features and territory success. Territory success had weak positive associations, for a given territory size, with conspecific density, although the relationship was highly variable. An interaction between territory size and density was not supported. These results are consistent with the view that avian breeding habitat selection occurs at multiple scales, and that the nest site scale may explain more of the variance in reproductive success than larger scales. Our results suggest that operational management of vegetation features, which often occurs at the stand scale, may not influence variation in critical demographic metrics. Increasing total shrub cover of commonly used plant species should benefit the dusky flycatcher, as well as other shrub-nesting forest birds, but stand-level habitat alterations alone cannot be relied upon to increase reproductive success, an important component of population change.     

Assessing the effects of initial soil characteristics,machine mass and traffic intensity on forest soil compaction

An extensive field trial was set up in eight forest stands to examine the influence of soil texture (two stands on sand, four on loam to silt loam, two on clay), machine mass (light, heavy) and traffic intensity (one and five skidding cycles) (i.e. pass back and forth on the skid trail) on soil compaction after mechanized harvesting. Dry bulk density (BD), penetration resistance (PR), micro-topography and soil carbon dioxide (CO₂) concentration were applied as response variables for soil compaction. Significant effects on BD were nearly absent (<7% increase) and occurred occasionally for PR (60–70% increase, up to 150% on clay soils). Especially for loam to silt loam and clay soils, this was in contrast with the expectation. The negligible compaction degrees for loam to silt loam are attributed to high initial compaction levels that prevented further compaction, as was found by general linear modelling (GLM) for both BD and PR. For clay soils the small compaction degrees can be explained by the high water contents that result in plastic deformation instead of strong compaction degrees, as was confirmed by the micro-topographical measurements. GLM also revealed a significant impact of machine mass (BD) and soil water content (BD, PR) on the compaction degree. Soil texture, traffic intensity and position in relation to the wheel tracks generally turned out to have an insignificant influence. With regard to clear interactions the influence of traffic intensity depends on the position in relation to the wheel tracks and the machine that was used (PR).