We determined the ultrasonic velocity and en- ergy attenuation value of three tree species （basswood, elm, and fir） 1 per tree in different moisture content levels, using RSM-SY5 ultrasonic testing instrument, and a...We determined the ultrasonic velocity and en- ergy attenuation value of three tree species （basswood, elm, and fir） 1 per tree in different moisture content levels, using RSM-SY5 ultrasonic testing instrument, and analyzed the regularity of ultrasonic velocity and energy attenuation values with moisture content, respectively. The ultrasonic velocity of the three species decreased as moisture content increased, with the turning point at 32 % of moisture content. When the moisture content was more than 32 %, the growth curve of ultrasonic wave velocity was flattened. The moisture contents of all three species increased under the any point moisture content of 1-60 %. The differen- tiation degrees of energy attenuation value of three species were higher than the corresponding ultrasonic wave ve- locity, when the moisture content was less than 15 %. The differentiation degrees of the energy attenuation value of three species was higher than the corresponding ultrasonic velocity, when the moisture content was more than 15 %.展开更多
粗头直径≥10cm,长度通常≥1m,倾斜度超过45°的死木质残体称为倒木（Harmon et al.,1996）。倒木是森林生态系统的重要组成部分,在森林生态系统中倒木与生产者、消费者、分解者之间都有着密切的营养关系,其结构与功能相互制约,相...粗头直径≥10cm,长度通常≥1m,倾斜度超过45°的死木质残体称为倒木（Harmon et al.,1996）。倒木是森林生态系统的重要组成部分,在森林生态系统中倒木与生产者、消费者、分解者之间都有着密切的营养关系,其结构与功能相互制约,相互影响。倒木对森林中生产者的更新有着不容忽视的作用,为各类植物提供了生境,而且还对森林生态系统的演替起着重要的作用（侯平等,2001）;展开更多
基金financially supported by‘‘The Fundamental Research Funds for the Central Universities’’,DL12BB12 and 2572014CB35
文摘We determined the ultrasonic velocity and en- ergy attenuation value of three tree species （basswood, elm, and fir） 1 per tree in different moisture content levels, using RSM-SY5 ultrasonic testing instrument, and analyzed the regularity of ultrasonic velocity and energy attenuation values with moisture content, respectively. The ultrasonic velocity of the three species decreased as moisture content increased, with the turning point at 32 % of moisture content. When the moisture content was more than 32 %, the growth curve of ultrasonic wave velocity was flattened. The moisture contents of all three species increased under the any point moisture content of 1-60 %. The differen- tiation degrees of energy attenuation value of three species were higher than the corresponding ultrasonic wave ve- locity, when the moisture content was less than 15 %. The differentiation degrees of the energy attenuation value of three species was higher than the corresponding ultrasonic velocity, when the moisture content was more than 15 %.
文摘粗头直径≥10cm,长度通常≥1m,倾斜度超过45°的死木质残体称为倒木（Harmon et al.,1996）。倒木是森林生态系统的重要组成部分,在森林生态系统中倒木与生产者、消费者、分解者之间都有着密切的营养关系,其结构与功能相互制约,相互影响。倒木对森林中生产者的更新有着不容忽视的作用,为各类植物提供了生境,而且还对森林生态系统的演替起着重要的作用（侯平等,2001）;
