华山松针叶中矿质元素含量的地理变异

以１２年生的种源林为取材对象，在１９９１年４月３０日、７月３０日、１０月３０日及１９９２年１月３０日同时采当年和１年生针叶，测定Ｎ、Ｐ、Ｋ、Ｃａ和Ｍｇ浓度。结果表明，除Ｋ外，其它矿质元素浓度种源间存在极显著差异。地理变异呈纬向渐变型。极端温度与元素地理差异有密切关系，并构成主导自然选择压。元素浓度的季节动态与针叶生长节律循环相伴。南、北华山松已分化成两个营养能力显著不同的地理种群，但动态模式基本相似。     

干热河谷和干性森林水分特征的对比分析

本文研究了川西南山地安宁河流域干热河谷和干性森林的水分收支状况。结果表明:(1)干热河谷和干性森林的年降水量分别为1 067.95 mm和1 371.73 mm,年降水量的90%以上集中在6月～10月的雨季和夏秋季节;(2)干热河谷和干性森林年蒸发量为1 280 mm和1 089.75 mm,春夏蒸发占年蒸发量的65%和66%,旱季蒸发占年蒸发量的58%和61%,4月～6月是蒸发旺季,其次是7月～8月;(3)干热河谷和干性森林年水分盈余量分别为43.6 mm和481.95 mm,均存在季节性水分匮缺期,7月～10月、夏秋季节和雨季均是水分盈余期,其余为水分匮缺期;(4)干热河谷和干性森林年干燥度分别为1.205和0.8,表明该地区分别为半湿润和湿润性气候,还存在明显的季节差异,7月～10月、雨季和夏秋季节气候湿润,其余时期为半湿润或干旱气候;(5)干性森林在年降水量和水分盈余量上高于干热河谷,在年可能蒸发量和干燥度上明显低于干热河谷,这种差异还体现在水分参数的月分配、四季分配、旱雨季分配上;(6)干热河谷湿润程度差于干性森林,干热河谷植被和干性森林对各自水分收支状况具有良好的适应性;(7)封山育林需要注意旱季防火,人工促进还需要考虑土壤水分平衡规律和适地适树,进行"适度"造林。     

日本落叶松自由授粉家系纸浆材材性遗传变异的研究

对12年生日本落叶松自由授粉子代测定林纸浆材材质性状进行了遗传变异分析、遗传参数估计、相关分析及综合评价和选择。结果表明:家系间综纤维素含量、基本密度、早材和晚材纤维长度、早材和晚材壁腔比差异极显著或显著,10g·L-1NaOH抽出物差异也达10%水平显著。各性状受强度或中等强度的遗传控制,对日本落叶松进行家系水平的材性改良具有很大的潜力。木材密度与早、晚材壁腔比、10g·L-1NaOH抽出物呈显著正相关,与综纤维素含量呈显著负相关,与早、晚材纤维长度相互独立;晚材纤维长度与早材纤维长度存在紧密正相关,纤维长度与早材壁腔比存在显著负相关关系,与晚材壁腔比、综纤维素含量和10g·L-1NaOH抽出物相互独立;综纤维素含量与早材壁腔比呈显著负相关,与晚材壁腔比相关不显著;10g·L-1NaOH抽出物与综纤维素含量、早、晚材壁腔比均相互独立。根据对日本落叶松材质性状的综合评价结果,选出最适合作纸浆林培育的249、340、346、217和364号家系。     

Temporal and spatial distribution of an invasive thrips species Scirtothrips dorsalis (Thysanoptera: Thripidae)

Dispersion of a new invasive thrips species in the United States, chilli thrips Scirtothrips dorsalis Hood, was studied on three plant hosts, i.e., cotton (Gossypium hirsutum L.), peanut (Arachis hypogeal L.) and pepper (Capsicum annum L.) in the greenhouse and under field conditions in Homestead, Florida. In the vertical distribution study, a strong negative relationship was observed between thrips density and height, with the significantly highest mean number of larvae and adults reported on host plants placed at the lowest height (45.7 cm) above ground. The study of horizontal distribution showed that S. dorsalis has weak dispersal potential and aggregates in open areas. During the entire six week study period, thrips were found to move a maximum of 12 m from their reservoir population. During two years (2009–2010 and 2010–2011) of study, a high abundance of thrips population was observed during May–October with the highest mean count during July and August in both years. Flight activity of adults was highest between 10:00and16:00 EST, during peak solar radiation (∼337–653 w/m²). Results from these studies will help growers and extension personnel predict farm-scale distribution of S. dorsalis and efficiently monitor the pest for management before they become a serious problem for the vegetable and ornamental industry in the United States.     

Bird-flower interactions in an urban area: Ceiba pubiflora provides nectar and promotes biodiversity in the city

Urbanization has negative effects on plant-animal interactions by reducing plant richness and increasing resource limitations. However, it is possible to replant these areas, and plant species can be selected based on the resources they provide, as well as their relationships with animals. I observed several trees of Ceiba pubiflora (Malvaceae, Bombacoideae) to identify the bird species interacting with their flowers in an urban area. This plant may be especially important, as it blossoms during the dry season, when the overall flower availability in the study area is low. It may also be important during a short period of decline in the fleshy fruit supply. Even though C. pubiflora was growing in the city and had a low volume of nectar accumulating in its flowers (mean of 1.73 μl; SD = 1.39 μl), it attracted a variety of birds (25 species belonging to six families), some of which are usually regarded as forest dependent. Nectarivorous birds from the family Trochilidae (hummingbirds, n = 12 species) had the highest percentage of visits (64.08%), especially during periods of relatively high nectar sugar concentration and calorie availability (c. 18% and 1.5 cal., respectively). Hummingbirds primarily acted as nectar thieves but also sometimes as potential flower pollinators. In contrast, several nonnectarivorous birds (frugivore-granivores, frugivore-insectivores and omnivores) acted only as nectar robbers or flower predators. Ceiba pubiflora flowers appear to be an important source of energy for birds in the urban area. The data of this study show that C. pubiflora has utility as management tool to promote and conserve biodiversity in cities.     

大英县近10年降水变化特点分析

利用大英县2004 ～2013年逐日降水资料,采用统计学方法,对大英近10年降水的实际变化特点、季节差异等进行简要阐述,并对直接影响工农业生产和人们生活、外出旅游以及交通运输等的暴雨进行了重点统计分析.结果表明,2004～2013年大英县年雨量和暴雨日数分布特征均呈单峰型,峰值均出现在7月;暴雨雨量、雨日与年降雨量存在明显的正相关关系;夏季同月雨量差距巨大;初秋的9月出现暴雨的概率较大,月雨量、暴雨出现次数均为全年的次高值;大英县出现秋绵雨的概率达50％,集中出现在9、10月.     

高黎贡山百花岭瓢虫群落结构及多样性研究Ⅱ——物种多样性的季节变化趋势

[目的]初步探明季节变化对高黎贡山百花岭瓢虫群落多样性的影响。[方法]2008年4月至2009年2月对高黎贡山百花岭瓢虫群落物种多样性的季节变化规律进行了研究。[结果]2008年4～6月瓢虫物种多样性逐渐上升,6、9月达到高峰,10月以后逐渐下降。气温和降雨量差异较小的月份瓢虫群落相似性较高。[结论]为进一步研究瓢虫多样性提供了理论依据。     

秸秆覆盖对季节性冻融期土壤水分特征的影响

以北方高寒区典型城市哈尔滨市为研究区域,通过冬季大田试验(试验周期2013-11-01—2014-04-30),设置自然无覆盖、覆盖秸秆厚度5、10、15 cm 4个处理,分别测定不同处理下20、40、60、100、140、180 cm深度土壤液态含水率以及气象数据,分析季节性冻融期秸秆覆盖对土壤水分变化特征的影响。研究结果表明:秸秆覆盖使0~60cm土层内液态含水率增加或减小的时间拐点发生延迟,随着秸秆覆盖厚度的增加其延迟效果越明显,但土壤冻结期的延迟效果比冻土融化期明显;秸秆覆盖阻碍了冻土融化初期融雪水入渗,使自然无覆盖处理液态含水率在20、40、60 cm土壤深度出现短暂的峰值,而在冻土融化末期秸秆覆盖抑制了土壤水蒸发,使各秸秆覆盖处理液态含水率在20、40、60 cm土壤深度又高于自然无覆盖。秸秆覆盖可有效平抑冻融期0~60 cm土层土壤液态含水率的变化幅度,且随着土壤深度的增加其平抑效果具有减弱趋势;积雪融水和秸秆覆盖的双重作用能够有效增加土壤墒情,但其增墒能力随着土壤深度的增加而降低,不同秸秆覆盖处理对0~60 cm土层的平均增墒能力由大到小排序依次为:15、10、5 cm。     

Seasonal patterns of photochemical capacity and spring phenology reveal genetic differentiation among native Scots pine (Pinus sylvestris L.) populations in Scotland

Environment-driven genetic differentiation among populations is a common feature among forest trees, and an understanding of how populations have adapted to their home site conditions is essential for management and conservation practices. In Scotland, 84 native Scots pine (Pinus sylvestris L.) woodlands are recognised by the Forestry Commission and they occupy highly diverse environments from the maritime west coast to continental sites in eastern Scotland. However, it is not known whether adaptations to local environments along sharp temperature and rainfall gradients have occurred in different populations and as a result, the seed transfer guidelines of the species are based only on data from isozymes and monoterpenes. In this study of an outdoor common-garden trial, we used chlorophyll fluorescence to examine whether seedlings from 32 open-pollinated families and eight populations from sites experiencing contrasting annual temperature regimes differed in their response to variation in natural outdoor temperatures between September 2009 and May 2010. In addition, growth initiation in spring was recorded. Photochemical capacity at photosystem II F_v/F_m showed a distinct seasonal trend and remained at relatively high levels (∼0.7) until November. Following a period of over 2 weeks with temperatures below or close to 0 °C, F_v/F_m started decreasing towards its minimum values recorded in early March when population means varied between 0.35 and 0.45. By early May and along with rising temperatures, photochemical capacity had recovered to the same level as observed in early November. Populations were found to respond differently to the cold period starting in December. The largest drop in photochemical capacity was observed in seedlings from a low-altitude population located in the maritime western Scotland, while in seedlings from higher-altitude locations in the cooler eastern Scotland, the response was smaller. In March, the recovery of photochemical capacity was slowest in seedlings from the mildest and coolest sites. Evidence of adaptive genetic differentiation was also found in spring phenology. Initiation of shoot elongation and needle flush were earlier in families from higher altitudes (cooler areas), but population differences were not significant at the α = 0.05 level. These results suggest that adaptation to the spatially heterogeneous environment in Scotland has taken place in Scots pine and that in order to minimise the risk of planting maladapted seed stock, the patterns of environmental and adaptive genetic variation should be taken into account in the management of genetic resources in this species.     

黔中玉米耕地土壤杂草种子库季节动态

对黔中玉米耕地土壤进行种子萌发试验,结果表明:玉米地杂草种子库共有44个物种出现,隶属16科40属。4个季节单位面积的种子萌发量Ⅰ季度8 609粒/m2>Ⅲ季度8 045粒/m2>Ⅱ季度6 491粒/m2>Ⅳ季度2 698粒/m2。狗尾草和水田碎米荠为上半年库中优势物种,下半年优势物种则为波斯婆婆纳。整体上随土壤层次的增加种子库存量相对减少,冬季活力种子萌发量最少;就物种多样性而言,种子库Shannon-W iener指数和Simpson指数均表现为Ⅱ>Ⅰ>Ⅲ>Ⅳ。