秦岭南北坡森林鼠类对板栗和锐齿栎种子扩散的影响

森林鼠类的种子贮藏行为对植物的扩散及更新会产生积极的影响。2012和2013年秋季,分别在秦岭北坡的周至国家级自然保护区和南坡的佛坪国家级自然保护区内,调查了森林鼠类对板栗(Castanea mollissima)和锐齿栎(Quercus aliena)种子的取食和扩散差异。结果显示:1)秦岭南北坡的环境因素,特别是植被因素,对鼠类扩散板栗和锐齿栎种子具有重要的影响。南坡较为丰富的壳斗科植被种类,导致2种种子在南坡存留时间均长于北坡,而北坡的扩散取食和丢失率均高于南坡。2)种子特征影响鼠类的取食或贮藏偏好。由于较高的蛋白、脂肪等营养含量,鼠类更喜好取食或搬运贮藏板栗种子。然而,低营养但高丹宁含量的锐齿栎种子仍然被鼠类大量贮藏。3)2种种子在南北坡的扩散历程在两个年份间有很大差异,在食物相对匮乏的年份(2012年),种子被扩散的速度更快且丢失的比率更高。这种差异反映了种子大小年现象对森林鼠类取食和贮藏策略的影响。4)无论在秦岭南坡还是北坡,营养价值含量(如蛋白和脂肪)较高的板栗种子的取食和贮藏距离都明显大于营养价值含量较低的锐齿栎种子,这与最优贮藏空间分布模型的预测一致。     

中西方森林游憩者生态行为影响研究——基于解说驱动机制视角

森林生态系统作为游憩经济系统的基础,保持生态结构完整是森林旅游协调发展的前提,但生态功能的发挥并非为旅游活动自然结果,很大程度有赖于游憩者的环境保护行为。选取加拿大班夫国家公园和中国张家界国家森林公园为问卷调研地,以解说驱动机制视角对森林游憩者生态行为影响进行研究,旨在运用相关分析、结构方程模型实证检验中西方森林游憩者生态行为生成的内在关联。结果表明:形成森林游憩者生态行为的过程逻辑定式为"生态知识-生态体验-生态态度-生态行为";1中西方森林游憩者生态知识、生态体验、生态态度与生态行为均存在正向相关;2森林旅游解说对中西方森林游憩者生态知识、生态体验、生态态度、生态行为均具有正向影响。     

半干旱区膜上覆土穴播对春小麦旗叶光合作用和水分利用的影响

在甘肃定西大田定位试验的基础上,2012—2013年连续2年比较了全膜覆土穴播(PMS)、覆膜穴播(PM)和露地穴播(CK)春小麦旗叶的SPAD值、叶绿素荧光参数、光合气体交换参数以及叶面积指数(LAI)、产量、耗水量和水分利用效率.结果表明: PMS提高了小麦旗叶SPAD值,扬花后显著高于PM,增加了10.0%～21.5%,较CK增加了3.2%～21.6%.PMS的旗叶最大光化学效率(F_v/F_m)、PSⅡ实际光化学效率(Φ_PSⅡ)和光化学猝灭系数高于PM和CK,较PM最高分别提高了6.1%、9.6%和30.9%,并在灌浆期达到显著差异;而PMS的非光化学猝灭系数(q_N)值最低,并在抽穗期与PM达显著差异水平,2012和2013年分别降低了23.8%和15.4%.PMS的气孔导度(g_s)较PM和CK高,在灌浆期与PM达到显著差异,2012和2013年分别提高了17.1%和21.1%;PMS的蒸腾速率(T_r)较PM提高了5.4%～16.7%,光合速率(P_n)增加了11.2%～23.7%,旗叶瞬时水分利用效率(WUE_i)提高了5.6%～7.2%(除2013年抽穗期外),并在2012年扬花期达到显著差异.PMS的LAI高于PM和CK,尤其在季节性干旱的2013年达到显著差异.因此,PMS提高了叶片SPAD值,增强了旗叶对光合能量的同化能力和气体交换强度,使更多的光合能量进入光化学同化方向,降低了热耗散,使P_n增加,提高了旗叶WUE_i,基于较高的光合速率和群体LAI,最终提高小麦产量和水分利用效率.     

持续施用缓/控释尿素条件下水田土壤NH3挥发与N2O排放特征

以持续9年施用不同缓／控释尿素的水田棕壤为试验对象,以普通大颗粒尿素为对照,研究了持续施用不同缓／控释尿素条件下水田土壤NH₃挥发与N₂O排放特征.结果表明: 与普通大颗粒尿素(U)相比,除1% 3,4－二甲基吡唑磷酸盐(DMPP)+U处理 NH₃挥发增加了25.8%外,其他缓／控释尿素肥料处理对NH₃有明显的减排效果.树脂包膜尿素(PCU)对NH₃减排效果最明显,为73.4%,硫包膜尿素(SCU)为72.2%,0.5% N-丁基硫代磷酰三胺(NBPT)+1% DMPP+U为71.9%,1% 氢醌(HQ)+3% 双氰胺(DCD)+U为46.9%,0.5% NBPT+U为43.2%,1% HQ+U为40.2%,3% DCD+U为25.5%, 1% DMPP均与施用普通大颗粒尿素差异显著;所有缓／控释尿素处理与对照相比均可显著减少N₂O排放.1% DMPP+U对N₂O减排效果最明显,为74.9%,PCU为62.1%,1% HQ+3% DCD+U为54.7%,0.5% NBPT+1% DMPP+U为42.2%,3% DCD+U为35.9%,1% HQ+U为28.9%,0.5% NBPT+U为17.7%,SCU为14.5%,均与施用普通大颗粒尿素差异显著.比较0.5% NBPT+1% DMPP+U、SCU、PCU对NH₃和N₂O减排的综合效果,3种肥料作用相近,且均明显优于其他处理,但包膜材料的成本较抑制剂高数倍.因此,同时添加脲酶和硝化抑制剂的缓释尿素是减少水田氮素损失及环境污染的首选氮肥.     

Optical Activity Governed by Local Chiral Structures in Two‐Dimensional Curved Metallic Nanostructures

Chiral nanostructures show macroscopic optical activity. Local optical activity and its handedness are not uniform in the nanostructure, and are spatially distributed depending on the shape of the nanostructure. In this study we fabricated curved chain nanostructures made of gold by connecting linearly two or more arc structures in a two‐dimensional plane. Spatial features of local optical activity in the chain structures were evaluated with near‐field circular dichroism (CD) imaging, and analyzed with the aid of classical electromagnetic simulation. The electromagnetic simulation predicted that local optical activity appears at inflection points where arc structures are connected. The handedness of the local optical activity was dependent on the handedness of the local chirality at the inflection point. Chiral chain structures have odd inflection points and the local optical activity distributed symmetrically with respect to structural centers. In contrast, achiral chain structures have even inflection points and showed antisymmetric distribution. In the near‐field CD images of fabricated chain nanostructures, the symmetric and antisymmetric distributions of local CD were observed for chiral and achiral chain structures, respectively, consistent with the simulated results. The handedness of the local optical activity was found to be determined by the handedness of the inflection point, for the fabricated chain structures having two or more inflection points. The local optical activity was thus governed primarily by the local chirality of the inflection points for the gold chain structures. The total effect of all the inflection points in the chain structure is considered to be a predominant factor that determines the macroscopic optical activity. Chirality 28:540–544, 2016. © 2016 Wiley Periodicals, Inc.     

Circadian rhythm in locomotor activity in the burrower crayfish Procambarus acanthophorus (Villalobos 1948)

Crayfish Procambarus acanthophorus is a burrower that spends long periods building deep tunnels to reach the water table during the dry season; thus, its survival entertains a close ecological relationship with the sediment. The aim of this work was to determine whether the properties of the circadian rhythm of locomotor activity could be modified by the sediment availability. Experiments were conducted in both aquaria filled with sediment or filled with water, under cycles of Bright and Dim Illumination (BI:DI, 12:12 h) or under continuous DI:DI. The rhythm of locomotor activity was entrained with the photoperiod in aquaria with sediment or water; however, statistical differences between conditions were obtained comparing the period and the level of activity under free-running. These data suggest that the substrate’s sensorial perception could be encoded as a significant ecological parameter that exerts influence in the physiological mechanisms that control the temporal order in P. acanthophorus.