秦岭辛家山不同林分土壤酶活性的剖面分布特征

土壤酶是土壤生态系统的重要组成成分,在土壤物质循环和能量交换过程中发挥着重要作用。调查了秦岭辛家山林区红桦(纯林)、云杉(纯林)和灌木3种天然次生林,分析了不同土层(0~10、10~20、20~40 cm和40~60 cm)β-1,4-木糖苷酶、β-1,4-葡萄糖苷酶、纤维二糖水解酶和β-N-乙酰基氨基葡萄糖苷酶活性的分布状况,并采用相关分析法分析了4种酶活性与土壤养分的相关关系。结果表明:1)红桦林土壤β-1,4-葡糖苷酶和β-1,4-木糖苷酶活性均高于云杉林和灌木林,云杉林土壤纤维素二糖水解酶活性高于红桦林和灌木林,而灌木林土壤β-N-乙酰基氨基葡萄糖苷酶活性高于云杉林和红桦林;2)除云杉林的纤维二糖水解酶外,3种林分土壤β-1,4-葡糖苷酶、β-1,4-木糖苷酶、纤维素二糖水解酶和β-N-乙酰基氨基葡萄糖苷酶活性均在0~10 cm达到最大值,且随着土层的加深而减少;3)相关分析表明,3种林分类型β-1,4-葡糖苷酶、β-1,4-木糖苷酶、纤维素二糖水解酶和β-N-乙酰基氨基葡萄糖苷酶活性均与土壤SOC、EOC、DOC和MBC显著正相关。表明酶活性在土壤的剖面变化不仅受到林分类型的影响,土壤养分含量同样是影响其分布的重要因素。

太白林区华山松叶蜂的发生与防治

2015—2016年对太白林区主要是陕西省太白林业局、太白山自然保护区华山松叶蜂发生情况进行调查,结果表明,华山松叶蜂在太白林区中山区1年发生2代,幼虫老熟后下树爬行寻找场所结茧化蛹越冬。该虫在中山地带山坡、沟谷地均有不同程度发生,5~20年生华山松有虫株率为16.70%~35.50%,虫口密度为63~536头/株。受害最重的是陕西省太白林业局太白河林场。该虫每年5月下旬始发,至10月下旬幼虫老熟后下树结茧化蛹越冬结束。针对华山松叶蜂的发生危害现状提出了综合防治方案。

Simulation analysis and implementation of spectral dispersion system based on virtually imaged phased array

Virtually imaged phased array(VIPA)has the advantages of insensitive to polarization,simple structure and high in spectral resolution.Compared with commonly used dispersive devices,such as diffraction gratings or Fabry-Perot(FP)interferometers,VIPA is self-aligned and has high transmission efficiency.In this paper,the dispersion mechanism of the VIPA is introduced in detail,the influence of incident angle and VIPA thickness on the dispersion performance near 532 nm is calculated and analyzed with MATLAB.According to the calculated results,the selected VIPA device has a thickness of 6 mm and an incident angle of 4°.The spectral dispersion system,in combination with corresponding optical devices,is designed and simulated with ZEMAX,then the experimental system was built.The spectral dispersion system based on VIPA,at a central wavelength of 532 nm,has the free spectral range of 15.08 GHz and the spectral resolution of 0.87 GHz.The system designed in this paper can be applied to high-resolution spectral detection such as Brillouin scattering,Raman scattering,laser fluorescence,laser-induced plasma and so on.