RESUMO
Negative air ion (NAI) is an essential indicator for measuring air cleanliness of a given area, with vital role in regulating psychological and physiological functions of human body. The photoelectric effect is an important source and influencing factor for the generation of NAI during photosynthesis, but the photoelectric effect is extremely weak and difficult to monitor. Plant electrical signal is an important indicator that indirectly reflects photoelectric effect. Previous studies mostly focused on the spatiotemporal variation of NAI in different forest communities and its relationship with meteorological factors. At present, there is little research on NAI and plant electrical signal. In this study, we explored the effect of different light intensities (0, 150, 300, 500, 700, 800, 1000 and 1200 µmol·m-2·s-1) on characteristics of the plant electrical signal and its relationship with negative air ion, with Pinus bungeana as the research object. The results showed that the intensity of plant electrical signal increased significantly with the increases of light intensity in the illumination range of 0-700 µmol·m-2·s-1. When light intensity reached 700 µmol·m-2·s-1, plant electrical signal activity reached the highest level, and plant was inhibited by light when light intensity increased further, with plant electrical signal activity decreased. The frequency-domain parameters (edge frequency, gravity frequency, power spectrum entropy and power spectrum peak) of plant electrical signals were significantly correlated with NAI. The correlation coefficient between edge frequency (E) and NAI was the highest, the relationship between them was NAI=30.981E+168.814 (R2=0.54), and the mean square error was 52.203. There was a significant correlation between plant electrical signals and NAI, which could characterize the change rule of NAI, and provide scientific evidence for further understanding the contribution potential and production mechanism of forest to NAI.
Assuntos
Eletricidade , Florestas , Plantas , Conceitos Meteorológicos , FotossínteseRESUMO
As an important ecological barrier for the North China Plain, research on the spatial variations of soil nutrients in the southern foot of the Taihang Mountains is of great significance for the forestry ecological construction in this rocky mountainous area. With the typical slopes (the artificial forestland and the natural wild slope) of the southern foot of the Taihang Mountains as the research objects, we used the grid method to arrange sampling points, and combined classical statistics, geostatistics and constrained sorting methods to analyze the spatial variations of soil nutrients. The results showed that: 1) soil total carbon (TC) contents were 6.80-57.05 g·kg-1, and the total nitrogen (TN) contents were 0.74-3.93 g·kg-1. The coefficients of variation of both soil TC and TN were 25.0%-52.8%, belonging to the moderate degree of variation, which were caused by the combination of random and structural factors. The spatial aggregation of soil nutrients decreased with increasing lag distances. 2) The contents of soil nutrients had increasing trends from the top to the bottom of the slopes, with high nutrient values appearing at the bottom of the slopes. 3) The soil bulk density, gravel content, vegetation coverage, and soil water content were the main factors affecting the spatial variability of soil TC and TN on the southern foot of the Taihang Mountains. 4) Soil water content was the main factor affecting soil nutrients at the natural wild slope, but not at the artificial forestland.
Assuntos
Nitrogênio , Solo , Carbono/análise , China , Florestas , Nitrogênio/análiseRESUMO
To explore the effects of forest types and slope positions on the content of soil organic carbon (SOC) and total nitrogen (TN) in the lower hilly area of Taihang Mountains, we examined the distribution pattern of SOC and TN contents in Quercus variabilis plantation (Qo), and Platycladus orientalis plantation (Po), and abandoned land (Al). The results showed that in the same forest type or slope position, the contents of SOC and TN gradually decreased with increasing soil depth. Under different slope conditions, the contents of SOC and TN showed the tendency of upper-slope (U) > middle-slope (M) > lower-slope (L) in the planted forests (Qo and Po), but showed the tendency of L>U>M in Al. Under different forest types, the contents of SOC and TN in the U and M showed the trend of Qo>Po>Al. At the LS, the contents of SOC and TN of Al were the highest. The C/N ratio followed an order of Qo>Po> Al at U and M, while Qo>Al> Po at L. Within the same forest type, C/N of different slopes was different, but not significant. Our results suggested that the adaptability of the Qo plantation is the best in the lower hilly area of Taihang Mountains.
