Phenological characteristics of net ecosystem carbon exchange of steppe in Inner Mongolia, China and its remote sensing monitoring.

To accurately monitor the phenology of net ecosystem carbon exchange (NEE) in grasslands with remote sensing, we analyzed the variations in NEE and its phenology in the steppe and discussed the remote sensing vegetation index thresholds for NEE phenology, with the observational data from the Inner Mongolia Xilinhot National Climate Observatory's eddy covariance system and meteorological gradient observation system during 2018-2021, as well as Sentinel-2 satellite data from January 1, 2018 to December 31, 2021. Results showed that, from 2018 to 2021, NEE exhibited seasonal variations, with carbon sequestration occurring from April to October and carbon emission in other months, resulting in an overall carbon sink. The average Julian days for the start date (SCUP) and the end date (ECUP) of carbon uptake period were the 95 and 259 days, respectively, with an average carbon uptake period lasting 165 days.

Regulatory effects of Hemin on prevention and rescue of salt stress in rapeseed (Brassica napus L.) seedlings.

Background: Salt stress severely restricts rapeseed growth and productivity. Hemin can effectively alleviate salt stress in plants. However, the regulatory effect of Hemin on rapeseed in salt stress is unclear.

Net ecosystem productivity of Panjin wetland during 1971 to 2020 and its impact factors.

Coastal estuarine wetland ecosystem has strong ability for carbon (C) storage and sequestration. Accurate assessment of C sequestration and its environmental impact factors is the basis of scientific protection and mana-gement of coastal estuarine wetlands. Taking the Panjin reed () wetland as the object, we used terrestrial ecosystem model, together with Mann-Kendall mutation test, statistical analysis methods, and scenario simulation experiment, to analyze the temporal characteristics, stability, changing trend of net ecosystem production (NEP) of wetlands and the contribution rate of environmental impact factors to NEP during 1971 to 2020.

[Effects of warming, photoperiod, and nitrogen addition on the main phenological phases of ].

With a large artificial climate chamber, we examined the effects of warming (control, +1.5 ℃, +2.0 ℃), photoperiod (10, 14, 18 h) and nitrogen addition (0, 5, 10, 20 g N·m·a) on the main phenological phases of in Northeast China.

[Temporal and spatial variations of net primary productivity (NPP) and its climate driving effect in the Qinghai-Tibet Plateau, China from 2000 to 2020].

Qinghai-Tibet Plateau is a "climate change laboratory" for China and the world. Driven by climate change, net primary productivity (NPP) in the Qinghai-Tibet Plateau has significant variations. Using the data of normalized difference vegetation index, digital elevation, annual precipitation, and annual temperature, we explored the temporal and spatial variation characteristics of NPP and its correlation with climate factors on the Qinghai Tibet Plateau from 2000 to 2020.

Photosynthetically physiological mechanism of Stipa krylovii withered and yellow phenology response to precipitation under the background of warming.

We examined the photosynthetically physiological mechanism of response to warming and precipitation changes, based on an experiment with the treatments of warming by infrared radiator and precipitation treatments by irrigation water. Under the warming background, precipi-tation was the main influencing factor of the withered and yellow phenology. Increasing precipitation postponed the occurrence time of both the beginning and the peak of the withered and yellow phenology, and prolonged the duration of the withered and yellow phenology.

Prominent vegetation greening and its correlation with climatic variables in northern China.

Global vegetation has been reported to be turning greener, especially in China and India. The Yellow River Basin is one of the most prominent greening areas in China. While some studies have attributed vegetation greening to large-scale ecological restoration efforts, our study focuses on the role of climate change in vegetation greening.

[Climate suitability of Ziziphus mauritiana in the main planting areas of Fujian Province, China].

Taiwan green jujube (Ziziphus mauritiana) is a new fruit variety, with remarkable economic benefit. To achieve high quality and high yield of jujube in Fujian Province, we quantified the climate suitability model parameters of the jujube in main production areas of Fujian, and analyzed climate suitability characteristics and change trend of main production areas, based on the yield and meteorological data, combined with literature and phenological observation data and agricultural climate suitability model. The results showed that the model based on the equal weight summation method had the highest reliability.

[Climatic suitability for the distribution of Vitis heyneana and V. davidii in China].

Vitis heyneana and V. davidii are two wild wine grape varieties that originate from China. In this study, we used the principle of maximum entropy in terms of sufficiency and necessity to identify the dominant climatic factors (among the many climatic factors that were brought up by previous relevant studies) affecting the planting distribution of both varieties in China.

[Fraction of absorbed photosynthetically active radiation over summer maize canopy estimated by hyperspectral remote sensing under different drought conditions.].

Fraction of absorbed photosynthetically active radiation (fAPAR) is one of the important remote sensing model parameters of vegetation productivity. However, the crop canopy fAPAR estimation during growing season under different drought conditions has not been reported yet. In this study, the characteristics of summer maize canopy fAPAR and spectral reflectance during growing season under different drought stresses and the relationships of fAPAR with reflectance, the first derivative spectral reflectance and vegetation indices were examined based on the hyperspectral reflectance and fAPAR data from the summer maize drought manipulation experiment with five irrigation levels in 2015.

[Influencing factors and their simulation of summer maize land surface-air temperature difference under drought conditions].

Crop water deficit status characterized by land surface-air temperature difference (T-T) has been widely investigated. However, empirical evidence for characteristics and impact factors of T-T considering the process of crop growth are less yet, which restricts the accurate simulation of T-T. Here, the data of T-T during the process of maize growth were obtained from five irrigation water control experiments after the period of summer maize 3-leaf stage in 2014 and jointing stage in 2015.

Grassland Carbon Budget and Its Driving Factors of the Subtropical and Tropical Monsoon Region in China During 1961 to 2013.

The southern grasslands are an integral part of the grassland ecosystems of China and play an essential role in the terrestrial carbon cycle of the country. We reproduced the spatiotemporal dynamics of the carbon budget of southern grasslands from 1961 to 2013 using the Terrestrial Ecosystem Model and our results showed that the annual carbon budget varied from -8.12 to 6.

[Maize biomass simulation based on dynamic photosynthate allocation.].

Photosynthate allocation is critical to crop growth and biomass formation, and it is also a key part of crop simulation. A photosynthate allocation model of maize was established based on photosynthate allocation mechanisms as well as the photosynthate allocation characteristics of maize at different stages. This model was then coupled with the CO assimilation module of WOFOST crop model to simulate the biomass dynamics of different organs of maize on daily scale.

[Leaf economics spectrum among different plant functional types in Beijing Botanical Garden, China.].

We measured leaf photosynthetic and chlorophyll fluorescence parameters as well as leaf area, dry biomass, and nitrogen content of different plant functional types (PFTs) at the Beijing Botanical Garden, and analyzed the leaf economics spectrum (LES) among different PFTs. The results showed that the plants with the life form of grasses, those with an annual type of life history, and with a C4 photosynthetic pathway might provide a quick return on investment for the species located at one end of the LES. Similarly, the plants with a life form of trees and shrubs, with a perennial type of life history, and with a C3 photosynthetic pathway might provide a slower return on investment for the species located at the other end of the LES.

[Soil moisture estimation method based on both ground-based remote sensing data and air temperature in a summer maize ecosystem.].

Soil moisture is an important component of the soil-vegetation-atmosphere continuum (SPAC). It is a key factor to determine the water status of terrestrial ecosystems, and is also the main source of water supply for crops. In order to estimate soil moisture at different soil depths at a station scale, based on the energy balance equation and the water deficit index (WDI), a soil moisture estimation model was established in terms of the remote sensing data (the normalized difference vegetation index and surface temperature) and air temperature.

[Effects of dynamic aerodynamic parameters on simulating the land-atmosphere flux exchange in maize field: a case study of BATS1e model].

Based on the continuous observations on the land-atmosphere flux exchange and the meteorological and biological elements in a maize field at the Jinzhou Agricultural Ecosystem Research Station in Liaoning Province of Northeast China from 2006 to 2008, and by using the dynamic roughness (z0) and zero-displacement (d) parameterization scheme considering the effects of leaf area index, canopy height and wind speed at different developmental stages of maize, the BATS1e model was modified, and applied to investigate the effects of dynamic aerodynamic parameters on the flux exchange between maize agroecosystem and atmosphere. Compared with the original model, the drag coefficient (C(D)) simulated by the modified model increased, and its diurnal variation was more obvious with increasing vegetation coverage, which was more accordant with practical circumstances. The simulation accuracies of sensible heat (H), latent heat (lambdaE) and soil heat flux were improved in varying degree, and the Nash-Sutcliffes (NSs) were increased by 0.

[Optimum field observation data for simulating maize leaf area index].

Leaf area index is a key indicator of leaf area change of crop population, and also, an important parameter for studying crop photosynthesis, transpiration, and biomass formation, etc. How to establish an optimum leaf area index (LAI) dynamic model with the minimum field observation data is of great significance for accurately simulating crop growth and yield. Based on the field experiment data of various spring maize varieties from the Jinzhou Agricultural Ecosystem Research Station in Northeast China in 2005-2011, in combination with the universal maize LAI dynamic model, this paper discussed the optimum field observation data for accurately simulating the dynamics of maize LAI.

[Impact of fire on carbon dynamics of Larix gmelinii forest in Daxing'an Mountains of North-East China: a simulation with CENTURY model].

Fire is one of the important natural disturbances to forest ecosystem, giving strong impact on the ecosystem carbon dynamics. By using CENTURY model, this paper simulated the responses of the carbon budget of Larix gmelinii forest in Huzhong area of Daxing' an Mountains to different intensities of fire. The results indicated that after the fires happened, the soil total carbon pool of the forest had a slight increase in the first few years and then recovered gradually, while the stand biomass carbon pool increased after an initial decrease, with the recovery rate of carbon pool of the stand fine components being faster than that of the coarse components.

[Relationships of forest fire with lightning in Daxing' anling Mountains, Northeast China].

Forest fire is an important factor affecting forest ecosystem succession. Recently, forest fire, especially forest lightning fire, shows an increasing trend under global warming. To study the relationships of forest fire with lightning is essential to accurately predict the forest fire in time.

[Climatic suitability of single cropping rice planting region in China].

To clarify the leading climate factors affecting the distribution of single cropping rice planting region in China at national and annual temporal scales and to reveal the potential distribution and climatic suitability divisions of this planting region in China could not only provide scientific basis for optimizing the allocation of single cropping rice production, modifying planting pattern, and introducing fine varieties, but also ensure the food security of China. In this paper, the potential climate factors affecting the single cropping rice distribution in China at regional and annual scales were selected from related literatures, and the single cropping rice geographic information from the national agro-meteorological observation stations of China Meteorological Administration (CMA), together with the maximum entropy model (MaxEnt) and spatial analyst function of Arc-GIS software, were adopted to clarify the leading climate factors affecting the potential distribution of single cropping rice planting region in China, and to construct a model about the relationships between the potential distribution of the planting region and the climate. The results showed that annual precipitation, moisture index, and days of not less than 18 degrees C stably were the leading climate factors affecting the potential distribution of single cropping rice planting region in China, with their cumulative contribution rate reached 94.

A temperature-precipitation based leafing model and its application in Northeast China.

Plant phenology models, especially leafing models, play critical roles in evaluating the impact of climate change on the primary production of temperate plants. Existing models based on temperature alone could not accurately simulate plant leafing in arid and semi-arid regions. The objective of the present study was to test the suitability of the existing temperature-based leafing models in arid and semi-arid regions, and to develop a temperature-precipitation based leafing model (TP), based on the long-term (i.

[Carbon exchange of Chinese boreal forest during its growth season and related regulation mechanisms].

Based on the two-year continuous observation on the carbon exchange of Chinese boreal forest during its growth seasons in 2007 and 2008 by the method of open path eddy covariance, this paper analyzed the seasonal dynamics of the gross ecosystem productivity (GEP), ecosystem respiration (Re), and net ecosystem carbon exchange (NEE) of the forest, with related regulation mechanisms approached. The GEP, Re, and NEE of the forest reached to their maximum in the vigorous growth period from late June to mid August, but the dates of the maximum appeared differed. The mean daily GEP, Re, and NEE were 19.