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... Therefore, the productivity level has been higher in the central region for about twenty years. With the increase in precipitation and temperature in recent years [40], productivity is gradually increasing slightly. The average annual productivity level in the southeastern part of Jilin is at level 4. ...
The spatiotemporal change characteristics of Cultivated Land Productivity (CLP) are imperative for ensuring regional food security, especially given recent global warming, social development and population growth. Based on the hypothesis that the Gross Primary Productivity (GPP) is a proxy of land productivity, the Moderate Resolution Imaging Spectroradiometer (MODIS) data with 500-m spatial resolution and 8-day temporal resolution was employed by the Vegetation Photosynthesis Model (VPM) to calculate GPP in Jilin Province, China. We explored the level of CLP using the GPP mean from 2000 to 2018, and analyzed the changing trend and amplitude of CLP in the whole study period using both Theil–Sen median trend analysis and the Mann–Kendall (MK) test, and forecasted the sustainability of CLP with the Hurst exponent. The trend result and the Hurst exponent were integrated to acquire the future direction of change. The results revealed that: (1) The CLP level was generally high in the southeast and low in the northwest in cultivated land in Jilin, China. The area with the lowest productivity, located in the northwest of Jilin, accounted for 15.56%. (2) The majority (84.77%) of the area showed an increasing trend in 2000–2018, which was larger than the area that was decreasing, which accounted for 3.97%. (3) The overall change amplitude was dominated by a slightly increasing trend, which accounted for 51.48%. (4) The area with sustainability accounted for 33.45% and was mainly distributed in the northwest of Jilin. The area with anti-sustainability accounted for 26.78% and was mainly distributed in the northwest and central Jilin. (5) The Hurst exponent result showed that uncertain variation of CLP is likely to occur in the future over the entire region, and the central region is prone to display degeneration. Therefore, the results of this study indicated that quality improvement policy could be implemented for the middle-to-low yield fields in northwest Jilin, and dynamic monitoring and protection measures could be implemented for the areas with uncertain future changes and decreasing sustainability.
Macrofungi are essential in forest ecological functioning. Their distribution and diversity are primarily impacted by vegetation, topography, and environmental factors, such as precipitation and temperature. However, the composition and topographical changes of the macrofungi between the eastern mountainous area and central plains of Jilin Province are currently unknown. For this study, we selected six investigational sites representing three different topographical research sites in Jilin Province to assess macrofungal diversity, and applied a quadrat sampling method. Macro- and micro-morphological characteristics combined with the molecular method were used to identify the collected macrofungi. Meanwhile, selected meteorological data were obtained for statistical analysis. As a result, 691 species were identified, of which Agarics were the most common, accounting for 60.23%, while the Cantharelloid fungi were the least common (0.91%). Furthermore, most of the shared genera (species) were saprophytic. The α diversity showed that the species diversity and richness in Longwan National Forest Park (B2) were the highest at the genus level. The mycorrhizal macrofungi proportion revealed that Quanshuidong Forest Farm (A1) was the healthiest. Finally, species composition similarity decreased with the transition from mountainous to hilly plains. We concluded that the occurrence of macrofungi was most influenced by vegetation. The air humidity, precipitation, and wind velocity were also found to significantly impact the occurrence of macrofungi. Finally, the mycorrhizal:saprophytic ratios and species similarity decreased with the transition from the mountainous area to the plains. The results presented here help elucidate the macrofungi composition and their relationship with environmental factors and topography in Jilin Province, which is crucial for sustainable utilization and future conservation.
Complexity analysis is an important tool for research on water resources. Although physical methods and quantitative detection are typically used to explore system complexity, this study uses a method combining probabilistic statistics with nonlinear science. The precipitation concentration index (CI), Mann-Kendall trend testing, probability density functions, and chaotic characteristic quantity are used to assess the spatiotemporal complexity of precipitation in Heilongjiang Province, China. The results show that the annual precipitation in Heilongjiang Province exhibits distinct spatial patterns; the highest values occurred at 128°E, gradually diminishing toward the east and west. Maximum precipitation was recorded at Shangzhi station (646 mm). A negative value of Z, an indicator of a precipitation trend, indicates a decreasing trend and a positive Z value indicates an increasing trend. In Yichun and Shangzhi, areas with greater precipitation, Z values were -1.21 and -4.88, respectively. In contrast, Z values were 3.02 and 0.93 in Qiqihar and Tailai, respectively, areas with lower precipitation. These findings indicate that precipitation differences between different regions have decreased, with the distribution becoming more uniform. Using ArcGIS to determine the chaotic characteristics of daily precipitation, values in the central and northeastern plains were high, whereas those in northwestern mountains were low. Maximum λmax values (3.456 × 10⁻³), an indicator of the degree of chaos, were obtained at the Yilan and Suifenhe stations, whereas the minimum value (9 × 10⁻⁵) was obtained at the Huma station. The authors analyze factors that influence the hydrological cycle in the study region by combining regional population and natural resource conditions. The results of this research will provide a reference for existing research and a theoretical basis for the scientific management of water resources in the region.
Anatomical characteristics have been proven useful for extracting climatic signals. To examine the climatic signals recorded by tree-ring cell features in the Changbai Mountains, we measured cell number and cell lumen diameter, in addition to ring widths, of Korean pine (Pinus koraiensis) tree rings at sites of varied elevation, and we developed chronologies of cell number (CN), mean lumen diameter (MLD), maximum lumen diameter (MAXLD) and tree-ring width (TRW). The chronologies were correlated with climatic factors monthly mean temperature and the sum of precipitation. As shown by our analysis, the cell parameter chronologies were suitable for dendroclimatology studies. CN and TRW shared relatively similar climatic signals which differed from MLD and MAXLD, and growth-climate relationships were elevation-dependent, as shown by the following findings: (1) at each elevation, MLD and MAXLD recorded different monthly climatic signals from those recorded by TRW for the same climatic factors; and (2) MLD and MAXLD recorded climatic factors that were absent from TRW at lower and middle elevations. Cell lumen diameter proved to be an effective archive for improving the climate reconstruction for this study area.
Precipitation time series were analysed using the Mann–Kendall (MK) test and wavelet analysis based on the mean seasonal and annual precipitation from 29 meteorological stations in Jilin Province for the period 1958–2011. Both the temporal and spatial distribution characteristics of the seasonal and annual precipitation trends and periodicities in different regions in Jilin Province were studied for the first time in this paper. New findings from the intensive calculations and appropriate analysis of data in longer period are as follows: (i) The annual precipitation of Jilin Province has experienced four states: a decrease (1958–1980), increase (1980–1987), decrease (1987–2003) and increase (2003–2011). (ii) The annual precipitation and seasonal precipitation increased from the northwest and northeast of the study area toward the south. (iii) Almost 90 % of the stations showed negative trends in annual precipitation variations. (iv) The trends in spring and winter are mainly increasing, whereas the trends in summer and autumn are mainly decreasing. (v) Jilin Province can be divided into four parts based on the periodicities of annual precipitation sequences: 5–6, 10–20 and 25–30 years in the northwest; 4–8 and 16–25 years in the centre; 7–8 and 13–17 years in the south and 5–10 and 12–17 years in the southeast.
The importance of a better understanding of the growth response of forest to climate change for managing and conserving forest has been realized. In this study, we developed the ring-width chronologies of Korean pine (Pinus koraiensis), one of the main constructive species of Changbai Mountain in northeastern China, to examine the radial growth–climate relationships. The stability of these relationships before and after abrupt climate change was evaluated. We built regression equations to project the future growth of the species under future climate change scenarios projected by the Providing Regional Climates for Impacts Studies (PRECISs) climate model. The results were as follows: (1) The chronologies in the three elevation gradients, HY1 at 740 m.s.l., FA at 940 m.s.l. and HY2 at 1258 m.s.l., had the good spatial similarity with high Gleichläfigkeit (GLK) indices; however, significant differences still existed between the growth–climate relationships of the three sites. The width chronology of Korean pine at site HY1 was positively correlated with the precipitation in September of the previous year (p < 0.01) and June of the current year (p < 0.05). The chronology at site FA was positively correlated with the temperature in March and April of the current year (p < 0.05). Whereas the current July temperature and the previous September precipitation were the main limiting factors for the growth of Korean pine at site HY2. (2) Mann–Kendall test results revealed that the climatic data from the meteorological stations near the sampling sites had an abrupt annual average temperature change in 1989, but the radial growth–climate relationship change only occurred in the chronology with May precipitation at site HY2, which may be caused by water stress. (3) With the projected increasing temperature and decreasing precipitation, compared with the base-line period (1971–2000), the radial growth of Korean pine at HY1 will relatively decrease, and the reduction will gradually increase. In contrast, at the higher elevation, like the FA and HY2 sites, the radial growth of Korean pine will relatively increase. Thus, the higher elevation areas of the Korean pine’s vertical distribution belt are more favorable for this species’ radial growth and forestation.
Based on the tree ring samples of Pinus koraiensis collected from the low altitude areas of Changbai Mountains, seven standard chronologies for tree ring width and cell scale parameters were constructed. Parts of the chronologies were chosen for the correlation analysis with the climate elements in 1959-2007 at Donggang meteorological station, and the changes of the correlations between tree ring indices and climate elements before and after 1988 in which the climate changed abruptly were discussed. In the seven standard chronologies constructed, cell number had the best correlation with tree ring width. Both precipitation and air temperature were the limiting factors for the growth of P. koraiensis, but the chronologies had better correlation with precipitation than with air temperature, mainly manifested in the significant correlation between the chronologies and the precipitation in previous September and current May and June. Comparing with tree ring width, cell size could reveal more climatic information, mainly manifested in the positive correlation between the chronologies and the air temperature in March and the precipitation in May, and the negative correlation between the chronologies and the air temperature in May. After the abrupt change of air temperature in 1988, the responses of cell size to climate elements had some changes, mainly manifested in the decreasing sensitivity to monthly climate elements and the earlier response time.
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