Content of High-quality development of forestry in the Yellow River Basin in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For Selected: Download Citations EndNote Reference Manager ProCite BibTeX RefWorks Toggle Thumbnails Select Water Balance Characters of Pinus tabuliformis Plantation in Xining City of China Wenhao Liu,Xiao Wang,Wenbiao Duan,Pengtao Yu,Yanhui Wang,Yipeng Yu Scientia Silvae Sinicae    2023, 59 (4): 46-56.   DOI: 10.11707/j.1001-7488.LYKX20220890 Abstract （142）   HTML （4）    PDF （914KB）（341）       Knowledge map    Save Objective: This study was aimed to deeply understand and quantitatively evaluate the hydrological effects of plantations ofPinus tabuliformis, an important afforestation tree species in Xining City, Qinghai Province of China, for providing scientific basis for the coordinated forest-water management. Method: Representative sample plots of middle-aged and closed stands of P. tabuliformis plantations were selected in the Huangshui Forest Farm, Xining City. During the growing season of 2021 (June-October), the variations of precipitation in open field, canopy intercession, stemflow, throughfall, tree transpiration, forest floor evapotranspiration, and soil moisture were monitored simultaneously, and the water yield from sample plots was calculated based on water balance. Result: The study showed: 1) The precipitation in the growing season amounted to 396.5 mm, while the canopy interception, tree transpiration, forest floor evapotranspiration amounted to 117.6, 109.4, 187.5 mm, respectively, accounting for 29.66%, 27.59%, 47.29% of precipitation during the same period, and showing an obvious monthly variation of firstly increase and then decrease. 2) The water storage of 0-100 cm soil layer was increased by 130.2 mm, showing an extra water input of 189.3 mm from outside (deep soil layers and upslope). The volumetric soil moisture of 0-100 cm soil layer varied as a consumption period from June to August, showing an overall decrease trend with values of volumetric soil moisture of always below 10%, indicating the existence of soil drought stress; while as a recovery period from September to October, showing a fluctuating upward trend with values of volumetric soil moisture of always above 9.3%. 3) The total evapotranspiration in the growing season amounted to 414.5 mm, which was 18.0 mm higher than the precipitation. After considering the influences of extra water input and soil water storage changes, the net water yield from the stand plot was calculated as ?18.0 mm, indicating that the plantation did not contribute to, but used/decreased the water yield from hillslope or watershed. Conclusion: In conclusion, even if the precipitation in the growing season of 2021 was higher than the mean annual precipitation of Xining City, the evapotranspiration of the closed stand of P. tabuliformis plantation cannot be satisfied by the natural precipitation under the semi-arid climate of Xining City. Therefore, it is necessary to maintain the stand stability against drought stress by lowering the tree density (canopy density) to reduce stand evapotranspiration or by appropriate irrigation to make up the water deficit, so as to ensure the desired dominant functions of urban landscape plantations. Table and Figures | Reference | Related Articles | Metrics Select Spatiotemporal Characteristics and Environmental Response of Vegetation Carbon Densities of Larix principis-rupprechtii Plantations in the Liupan Mountains of Ningxia, China Ziyou Zhang,Yanhui Wang,Ao Tian,Zebin Liu,Jianbin Guo,Pengtao Yu,Xiao Wang,Yipeng Yu Scientia Silvae Sinicae    2023, 59 (4): 32-45.   DOI: 10.11707/j.1001-7488.LYKX20230037 Abstract （174）   HTML （17）    PDF （2227KB）（388）       Knowledge map    Save Objective: In this study, the spatiotemporal variation of vegetation carbon densities (VCD) of the tree layer, understory shrub layer and herb layer of larch (Larix principis-rupprechtii) plantations in the Liupan Mountains area of southern Ningxia of northwest China were investigated and analyzed, and the VCD models considering the effects of multiple factors of site quality and stand structure were established, so as to provide theoretical basis and decision-making tools for estimating VCD and their sustainable management of the larch plantations under complex topographic conditions in the mountainous regions of northwest China. Method: The VCD of tree, shrub and herb layers of larch plantations in the study area was determined by the combined application of sample plot inventory and mathematical models. The upper boundary line method was used to determine the response pattern and corresponding function form of VCD to each main influencing factor (forest age, density, mean annual precipitation, mean annual air temperature, slope aspect). A VCD model that can reflect the comprehensive impact of multiple factors was constructed through multiplicative coupling, and then the measured data were used to calibrate and validate the model. Result: 1) The average VCD of the existing larch plantations in the Liupan Mountains area was 46.82 t C·hm-2, of which the tree layer accounted for 94.92%, while the shrub layer and herb layer only accounted for 4.76% and 0.32%, respectively. 2) The VCD of tree layer firstly increased rapidly with the increase of forest age, stand density, and mean annual precipitation, and then increased slowly and gradually tended to its maximum value after exceeding the certain threshold values of those factors. The corresponding threshold values for those influencing factors were 30 years of forest age, 1500 tree·hm-2 of tree density, and 525 mm of mean annual precipitation. The VCD of tree layer firstly increased and then decreased with rising mean annual temperature and reached its peak at 6°C. It decreased nearly linearly with rising slope aspect (0° to due north, increasing with the deviation angle from north direction to both sides). 3) The VCD of the understory shrub-herb layers decreased linearly with rising tree layer VCD, and varied with mean annual temperature and precipitation as well as slope aspect in the same patterns of tree layer VCD and the same threshold values of 6 °C and 525 mm. 4) The established multi-factor coupled model of VCD was able to better estimate the variation of VCD of tree layer and understory shrub-herb layer, with R2 of 0.8** and 0.7**, respectively. (5) According to simulation results of the model, the VCD of larch plantations firstly increased and then decreased with rising elevation, showing a relatively bigger difference among elevation gradients, the elevation range with the highest VCD was 2200—2400 m. Due to the effects of topography and climatic factors, there existed a certain horizontal difference, namely decreasing from west to east and from south to north. The VCD on shady slopes was higher than that on sunny slopes, with a difference of about 20% for tree layer and up to 100% for shrub-herb layers. Conclusion: The average VCD of the larch plantations in Liupan Mountains area is 46.82 t C·hm-2 and mainly composed of tree layer. The VCD is jointly affected by the multiple factors of site quality (precipitation, temperature, slope aspect) and stand structure (age, density). The VCD of understory shrub-herb layers is also influenced by the tree layer biomass. The spatiotemporal variation of VCD of larch plantations can be better explained and predicted by the multi-factor coupled model. The reasonable selection of site types for afforestation and tree density for forest management is beneficial to maintain a better VCD with expected vegetation layer composition for the larch plantations. Table and Figures | Reference | Related Articles | Metrics Select Variation and Evaluation of Site Index of Black Locust Plantations on the Loess Plateau of Northwest China Pingping Li,Yanhui Wang,Wenbiao Duan,Yirui Wang,Pengtao Yu,Li Zhen,Zhixin Li,Huijun Shang,Zaijun Shi,Yipeng Yu Scientia Silvae Sinicae    2023, 59 (4): 18-31.   DOI: 10.11707/j.1001-7488.LYKX20220621 Abstract （181）   HTML （17）    PDF （1245KB）（387）       Knowledge map    Save Objective: The response of average height of dominant trees and site index (the average height of dominant trees with a baseline forest age of 15 years) of black locust (Robinia pseudoacacia) plantations to climatic and site factors was studied on the Loess Plateau, for establishing a model to evaluate site quality. Method: Based on the survey of sample plots and collected literature data, the single factor response law and appropriate form of response function of the average height of dominant trees were determined using the envelope method, and then a model was established by coupling multiple factors and calibrated with the measured data to evaluate the spatial difference in site index. Result: The impact of topography positions on the average height of dominant trees varied greatly, with a relative score of: gully bottom 1.000 > tableland 0.906 > lower part of ridge slope 0.837 > middle part of ridge slope 0.438 > gully slope 0.210 > upper part of ridge slope 0.176 > hilly top 0.000. Within the variation range of mean annual precipitation (MAP) below 550 mm, the average height of dominant trees increased with rising MAP rapidly, and thereafter gradually tended to level-off; the average height of dominant trees increased first and then decreased with rising mean annual air temperature (MAT) , with an optimal range of 7.5–11.0 ℃. The model of average height of dominant trees was established by coupling the effects of climatic and site factors, with a satisfactory fitness ( R2 = 0.72). According to the effects on the average height of dominant trees, both MAT and MAP on the Loess Plateau were divided into four levels (<6.0 ℃, too cold to grow; 6.0–7.5 ℃, cold and not suitable or relatively suitable for growth; 7.5–11.0 ℃, mild and the most suitable for growth; >11.0 ℃, warm and relatively suitable or not suitable for growth. <400 mm, too dry to grow; 400–450 mm, dry and not suitable for growth; 450–550 mm, moist and more suitable for growth; >550 mm, wet and the most suitable for growth). Then, the areas where black locust afforestation cannot be carried out on the Loess Plateau were determined, and the climate zoning of the rest areas where black locust afforestation can be carried out was proposed. The mild-wet, mild-moist, warm-wet and mild-dry subzones are suitable for black locust growth with an average site index of medium or higher classes (>7.5 m); while the cold-dry/moist and warm-moist subzones are not suitable for black locust growth as a whole. The site index of all site types in each subzone was calculated using fitted model for evaluating the site quality. Conclusion: The site index of black locust plantations on the Loess Plateau is affected by both climatic and site factors. The climatic zoning and site assessment with site index considering these effects can guide the refined site selection for afforestation and rational management of black locust plantations on the Loess Plateau. Table and Figures | Reference | Related Articles | Metrics Select Forest-Water Coordinated and Multifunctional Management of Forests in the Liupan Mountainous Area and Loess Plateau Region of China Yanhui Wang,Pengtao Yu,Ao Tian,Xinsheng Han,Jia Hao,Zebin Liu,Xiao Wang Scientia Silvae Sinicae    2023, 59 (4): 1-17.   DOI: 10.11707/j.1001-7488.LYKX20220859 Abstract （242）   HTML （23）    PDF （982KB）（478）       Knowledge map    Save Objective: Facing the requirements of implementing the major national strategy of Yellow River Basin ecological protection and high-quality development, and of promoting the integrated management of “mountains, rivers, forests, farmlands, lakes and grasslands” systems in China, the traditional approaches of forestry development and vegetation restoration in dryland regions, such as the Loess Plateau, must be changed by adding the considerations of water resources limitation and the impacts on water resources, and by paying attentions to the optimization of multiple forest functions/services. It is required to explore how to overcome the long-standing problems of neglecting water carrying capacity, low afforestation survival rate and poor tree growth, river runoff reduction and endangering to regional water supply safety, and the overall low functions of forests, so that to achieve the overall improvement of the multifunctionality of forests through their scientific management. Method: To meet the scientific and technical requirements of deep understanding of forest-water interrelations and of multifunctional forest management (MFFM), long-term studies since 2000 on the dryland forest ecohydrology and MFFM techniques were carried out in the Jinghe River basin and the regional important source-water area of the rocky Liupan Mountains on the Loess Plateau of northwest China. These studies were designed around the key issues of “structure”, “pattern”, “process”, “coupling”, and “scale”, using the multiple methods of observation comparison and statistical analysis as well as model simulation, at multiple scales from single tree to region. Result: The studies showed that: 1) The essence of high-quality forestry development is MFFM with quantitative and precise decision-making. Therefore, it is required to deeply understand and precisely quantify the impacts of site conditions and stand structure on the multiple functions of forests, to clarify the importance order of forest functions based on their complex interactions and supply-demand relations, and to optimize the competing functions to meet the societal demands of both dominant and other functions simultaneously under the precondition of ensured forest stability, by the rational designing and regulation of forest quantity, quality (structure) and spatial distribution pattern within basins. 2) The forest-water coordinated and multifunctional management approach was proposed, this means that besides considering the restrictions of available land area and seedlings and site quality for afforestation, new considerations should be added to the water resources management and MFFM through embedding them into the traditional single-function oriented decision processes of forest management. These decision processes involve four decision levels, they are the rational forest cover of basins (how much to afforest?), forest spatial distribution (where to afforest?), vegetation type and tree species composition (with which tree species?) and stand structure (how to manage forests?). 3) The related technical achievements were summarized according to the decision levels. For determining the reasonable forest cover of loess basins, the potential forest cover merely based on the annual precipitation limit can be updated to the reasonable forest cover by considering both the precipitation limit and water yield requirement through using the established empirical relations and the simulation results of watershed hydrological models. 4) For making the decisions of reasonable spatial distribution of forests within basins, the water yield differences among site types and their responses to afforestation should be utilized with the help of simulation results of distributed hydrological models or the regional vegetation carrying capacity calculation system developed in this study. For the MFFM decision at stand scale, a five-step decision-making procedure was suggested, namely, site quality classification, determining main functions and their priorities for each site type, investigating the structure characteristics of existing forest stands, diagnosing the structure and functions of existing forest stands, and compiling a structure/function-oriented management plan. For setting up the reference and goal of MFFM, ideal stand structures of multifunctional water-retention forests with different degrees of detail were proposed: the generalized ideal stand structure expressed as “3×0.7+X” (canopy density around 0.7, 0.6–0.8; ground coverage above 0.7; ratio of tree height to DBH below 0.7 m/cm, at least not higher than 0.9; X presents other requirements), the multifunctional density of middle-aged larch (Larix principis-rupprechtii) plantations determined by weighing the density needs of individual functions and stand stability, the varying multifunctional densities of larch plantations along elevations and ages determined based on the variation rules of main forest functions and their priorities. Conclusion: The theoretical advancement and technical feasibility of forest-water coordinated multifunctional management has been proved, as a viable way to realize the high-quality forestry development in dryland regions. Through a thorough understanding and quantitative analysis of the multiple functions with varying environment and forest structure, combined with the application of MFFM techniques proposed in this paper, the rational forest quantity (forest cover), quality (structure), and distribution pattern can be scientifically designed and adjusted, to realize the overall promotion of multiple functions to better meet the diverse societal demands. However, the achievements are still limited, thus more theoretical and technical research of forest-water coordinated and multifunctional management of forests should be carried out according to local situations to help the life community governance of “mountains, rivers, forests, farmlands, lakes and grasslands” systems and the ecological protection and high-quality development of the Yellow River Basin. Table and Figures | Reference | Related Articles | Metrics