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The aim of this study was to analyze the phylogenetic composition of the bacterial community in the air at the Mogao Grottoes (Dunhuang, China) using a culture-dependent molecular approach. The 16S rRNA genes were amplified directly from the isolates with universally conserved and bacteria-specific rRNA gene primers. The PCR products were screened by restriction fragment length polymorphism, and representative rRNA gene sequences were determined and sequenced. A total of 19 bacteria genera were identified among 49 bacterial sequence types. Phylogenetic sequence analyses revealed high diversity within the bacterial community. The most predominant bacteria were Janthinobacterium (14.91%), Pseudomonas (13.40%), Bacillus (11.25%), Sphingomonas (11.21%), Micrococcus (10.31%), Microbacterium (6.92%), Caulobacter (6.31%), and Roseomonas (5.85%). The composition of bacterial communities differed greatly between different sites and at different times. The distribution of various bacteria was mainly affected by climatic parameters and human activities. These findings suggested that the opening of this cultural heritage site to visitors should be controlled and that maintaining the cave's natural climatic conditions would aid the conservation and management of the grottoes' paintings.

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In modeling the canopy reflectance of row-planted crops, neglecting horizontal radiative transfer may lead to an inaccurate representation of vegetation energy balance and further cause uncertainty in the simulation of canopy reflectance at larger viewing zenith angles. To reduce this systematic deviation, here we refined the four-stream radiative transfer equations by considering horizontal radiation through the lateral "walls", considered the radiative transfer between rows, then proposed a modified four-stream (MFS) radiative transfer model using single and multiple scattering. We validated the MFS model using both computer simulations and in situ measurements, and found that the MFS model can be used to simulate crop canopy reflectance at different growth stages with an accuracy comparable to the computer simulations (RMSE < 0.002 in the red band, RMSE < 0.019 in NIR band). Moreover, the MFS model can be successfully used to simulate the reflectance of continuous (RMSE = 0.012) and row crop canopies (RMSE < 0.023), and therefore addressed the large viewing zenith angle problems in the previous row model based on four-stream radiative transfer equations. Our results demonstrate that horizontal radiation is an important factor that needs to be considered in modeling the canopy reflectance of row-planted crops. Hence, the refined four-stream radiative transfer model is applicable to the real world. accuracy than the computer-simulated calculation for each leaf scattering [11,12], it greatly reduces the calculation time. Therefore, considering the comprehensive efficiency of accuracy and time, the radiative transfer modeling method has a faster calculation time and higher calculation accuracy, making it a commonly used model in remote sensing inversion that is able to improve the efficiency of the inversion of biophysical parameters.For studies on modeling techniques of radiative transfer in agriculture, the prevailing model is the SAIL model (light scattering by leaf layers with application to canopy reflectance modeling), which is one of the models in the four-stream radiative transfer equations that were developed into an approximate solution method [13] and simplified with an integral-differential radiative transfer equation for vegetation [10], especially in the calculation of multiple scattering contributions in canopy reflectance [10,14,15]. The four-stream radiative transfer equations originated from K-M equations (it is the equations proposed by Kubelka, P. and Munk, F.; hence, it is named as K-M equations) [16]. K-M equations used two ordinary differential equations to represent the energy relationship between downward hemispherical diffuse flux density (E − ) and upward hemispherical diffuse flux density (E + ) in infinitely extended layers. Afterwards, downward specular irradiance (E s ) is considered in the extinction of specular flux. Allen [17] proposed the three-stream radiative transfer equations and first used these equations to solve canopy reflectance for remote sensing. Finally, Suits [18] co...