[Soil stoichiometry of Pinus massoniana forest in red soil erosion area under different management patterns]. / 红壤侵蚀退化马尾松林下不同治理模式土壤化学计量特征.

We investigated the concentrations of carbon (C), nitrogen (N), and phosphorus (P) and C:N:P stoichiometry in soil and litter of Pinus massoniana forest under four different management patterns: inefficient forest transformation, mixture of arbor with shrub and herb, shallow ditch grass planting, and being banned in serious erosion and degradation of red soil in southern China. Our findings could provide scientific basis for soil erosion control and vegetation restoration in this area. The results showed that there were significant differences in soil organic carbon (SOC), TN, TP and litter nutrient content among different management patterns. The nutrient contents in soil and litter under all the four management patterns were significantly higher than that of control, with mixture of arbor with shrub and herb having the highest concentrations. The concentrations of SOC, TN and TP decreased with the increases of soil layer. However, the shallow ditch grass planting mana-gement pattern presented as follows: the concentrations of SOC, TN and TP decreased first and then increased with the increases of soil layer, with the lowest value in 5-20 cm soil layer. There were significant differences in soil C:N, C:P, N:P and litter C:P among different management patterns, and the soil spatial variation was C:N>C:P>N:P. Excepted for mixture of arbor with shrub and herb, C:N was still at a lower level in the other management patterns, and soil C:P and N:P showed higher values overall. Litter C:N, C:P and N:P had opposite change pattern, with inefficient forest transformation and mixture of arbor with shrub and herb being much smaller than the control. Soil C:N and C:P were mainly controlled by SOC content and litter C content, and soil N:P was mainly controlled by soil TP content and litter P content. Soil stoichiometry was affected by soil water content, soil bulk density, pH, and other factors. The relationship between litter and soil nutrients was closely related and showed similar changes.

Ambient temperature-independent dual-band mid-infrared radiation thermometry.

For temperature measurements of targets at low temperatures, dual-band radiation thermometry using mid-infrared detectors has been investigated extensively. However, the accuracy is greatly affected by the reflected ambient radiation and stray radiation, which depend on the ambient temperature. To ensure measurement accuracy, an improved dual-band measurement model is established by considering the reflected ambient radiation and the stray radiation. The effect of ambient temperature fluctuation on temperature measurement is then further analyzed in detail. Experimental results of measuring a gray-body confirm that the proposed method yields high accuracy at varying ambient temperatures. This method provides a practical approach to remove the effect of ambient temperature fluctuations on temperature measurements.