| 野外叶面积指数自动测量仪器设计及应用试验 |
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| 引用本文： | 温一博,范文义,常 颖,李明泽,于宏洲,王宇航.野外叶面积指数自动测量仪器设计及应用试验[J].农业工程学报,2015,31(9):154-160. |
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| 作者姓名： | 温一博 范文义 常 颖 李明泽 于宏洲 王宇航 |
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| 作者单位： | 东北林业大学林学院，哈尔滨 150040,东北林业大学林学院，哈尔滨 150040,东北林业大学林学院，哈尔滨 150040,东北林业大学林学院，哈尔滨 150040,东北林业大学林学院，哈尔滨 150040,东北林业大学林学院，哈尔滨 150040 |
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| 基金项目： | 十二五国家科技支撑项目（2011BAD08B01）；中央高校基本科研业务费专项资金项目（2572014AA37） |
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| 摘 要： | 为提高长时间序列叶面积指数测定模型的模拟精度,该文设计一种可以长期在野外间接测量叶面积指数仪器,仪器由太阳能提供持久电能,利用单片机控制垂直水平舵机,带动光强传感器记录多角度光线强度,在2台仪器同时测量的情况下,获得光线透过林分冠层多角度光强衰减率,通过编写计算程序解算林分叶面积指数。使用商品化光学仪器LAI-2200验证该仪器测量精度,对24块样地叶面积指数进行测量,两仪器测量结果高度吻合R2为0.927,绝对标准误差为0.36。长时间野外叶面积指数自动测量获取数据可节省人力、减少人为误差。
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| 关 键 词： | 仪器 测量误差 设计 叶面积指数 长期测量 设计 单片机 |
| 收稿时间： | 2014/10/31 0:00:00 |
| 修稿时间： | 2015/3/24 0:00:00 |
Design and applied experiment of long time series leaf area index measuring instrument |
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| Wen Yibo,Fan Wenyi,Chang Ying,Li Mingze,Yu Hongzhou and Wang Yuhang.Design and applied experiment of long time series leaf area index measuring instrument[J].Transactions of the Chinese Society of Agricultural Engineering,2015,31(9):154-160. |
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| Authors: | Wen Yibo Fan Wenyi Chang Ying Li Mingze Yu Hongzhou and Wang Yuhang |
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| Institution: | College of Forestry, Northeast Foresty University, Harbin 150040, China,College of Forestry, Northeast Foresty University, Harbin 150040, China,College of Forestry, Northeast Foresty University, Harbin 150040, China,College of Forestry, Northeast Foresty University, Harbin 150040, China,College of Forestry, Northeast Foresty University, Harbin 150040, China and College of Forestry, Northeast Foresty University, Harbin 150040, China |
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| Abstract: | Abstract: Leaf area index (LAI) objectively describes the number of leaves, is a key parameter controlling many biological and physical processes associated with vegetation on the earth's surface, such as photosynthesis, carbon and nutrient cycle, radiative balance, evapotranspiration, and rainfall interception. Thus, LAI is widely used in models of ecology, hydrology, biogeochemistry and climate. Accurately measuring LAI is one of the hotspots in the study of earth science. Long time series LAI is an important input parameter of daily forest carbon and water cycle models, and its accuracy directly influences the result of the model simulation. At present, site measurements of Long time series LAI data expend a large number of repeated manual operations, and produce a great error in the operation. An instrument, with which LAI can be indirectly measured in the field for a long time, was designed in this study. This instrument consisted of solar power system, single-chip microcomputer control system and time control system. The single-chip microcomputer control system was mainly made up of Arduino UNO microcontroller, clock module, storage module, display monitor module steering engine, light intensity sensor, temperature sensor and humidity sensor. In order to prevent the extra light intensity of a single direction that affected the accuracy of measurement, the measuring time was set at 7:00-8:00 and 16:00-17:00 by the time-control system. The solar batteries provided durable electric energy for the instrument. The vertical and horizontal rotary servos were controlled by microcontroller which drove the light sensor to record the light intensity from different solar zenith angles. It can record the light intensity from the zenith angles of 0°, 12°, 24°, 36°, 48°, 60°. Two instruments were used at the same time to measure LAI. One instrument was placed under the forest canopy in a plot to measure light intensity through the canopy, another instrument was placed in some open place, such as forest station, to measure light intensity equivalent to that above canopy. The light transmittance through the canopy was calculated by the ratio of the measured data of the two instruments respectively at different angles. LAI calculation was based on radiation transmission through the canopy. The commercial optical instrument LAI-2200 was used to test and verify the measurement precision of this instrument. LAI was measured on 24 plots, which were set in the experimental forest of Northeast Forestry University. The size was 20×30 m2. The minimum value of LAI was 1.625, the maximum was 6.323 and an average was 4.21 by using this instrument. The minimum value of LAI was 1.97, the maximum was 6.04 and an average was 3.99 by using LAI-2200. The research showed that the result of Long time series LAI measuring instrument was highly consistent with commercial optical instrument LAI-2200, with R2 of 0.927, RMSE of 0.36. The cost of the instrument was low, and with such instrument, network measurement would be possible among different forests. The stable operation of the instrument in high humidity environment of the forest was due to its waterproof design. When LAI was measured, the instrument collected data of air temperature and humidity to provide accurate environmental data for the study of long time series LAI changes. All collected data were recorded in the SD card, which was convenient for data application. |
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| Keywords: | instruments measurement errors design leaf area index long-term observation design single chip microcomputer |
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