In the process of coping with global warming,how to mitigate the negative effects of greenhouse effect has aroused widespread concern.Mangrove carbon sink is an important contributor to global ecosystem carbon sink,and it is also a type of carbon sink recognized by the United Nations Framework Convention on Climate Change and can be used as a clean development mechanism project,and is a breakthrough to establish China's blue carbon trading market.In practice,most of China's mangrove carbon sink trading cases are led by the government,and the problem of insufficient play of the market mechanism is still prominent.In order to give full play to the potential of mangrove carbon sink,this paper analyzed the advantages,disadvantages,opportunities and challenges of mangrove carbon sink trading,and found out that mangrove carbon sink trading possessed strong development potential,and putforward relevant suggestions on constructing the marketization path of mangrove carbon sink trading in China,so as to promote the sustainable development of mangrove carbon sink trading in China.
Firstly,based on 50 standard survey data,TWINSPAN method was used to classify 50 standard communities into different community types.Secondly,the α-diversity and β-diversity of different community types were analyzed to determine the difference of plant diversity among different community types.Finally,using redundancy analysis,plant diversity and influencing factors of different plant communities in Zengcheng Forest Farm were explored.The results showed as follows:1)The plants in Zengcheng Forest Farm included 84 families,189 genera and 270 species,which could be divided into 10 plant communities,among which the dominant communities were"Ass.Machilus chinensis+Schima superba+Lophatherum gracile","Ass.Castanopsis fissa+Heptapleurum heptaphyllum+Psychotria asiatica"and"Ass.Cunninghamia lanceolata+Schima superba+Lophatherum gracile".2)There were significant differences in α-diversity among different plant community types.The α-diversity was the most abundant in the community of"Ass.Mallotus paniculatus+Heptapleurum heptaphyllum+Blechnopsis orientalis"and the community of"Ass.Cunninghamia lanceolata+Schima superba+Lophatherum gracile",followed by the community of"Ass.Machilus chinensis+Schima superba+Lophatherum gracile",and the community of"Ass.Eucalyptus grandis x urophylla+Microstegium vimineum"was the simplest.Compared with other communities,the average p-diversity index of the community of"Ass.Machilus chinensis+Schima superba+Lophatherum gracile"was the highest,indicating the least interspecific competition and the strongest community stability.3)Stand cover and dominant tree species had significant effects on plant diversity,while stand density and altitude had significant effects on plant diversity.In summary,the comprehensive plant diversity of"Ass.Machilus chinensis+Schima superba+Lophatherum gracile"was the best.By adjusting the stand density of the dominant tree species to optimize the stand structure,the stand can be transformed in the direction of"Ass.Machilus chinensis+Schima superba+Lophatherum gracile"in forest management activities,so as to further enrich the plant diversity and enhance the system stability.
The objective of this research was to investigate different stand age classes of fine root carbon(C),nitrogen(N)and phosphorus(P)stoichiometric characteristics and their storages.Five representative soft-broadleaved forests were selected as the research objects.Fine root samples were taken at depth intervals of 0～＜20 cm and 20～40 cm soil layers in each sample-plot for indoor measurements.And the variation laws were investigated for different age classes and different soil layers for the fine root C,N,P stoichiometric characteristics and their storages in GuangXi soft-broadleaved forests.The result showed that:1)the C content of fine roots did not have a significant change with the change of forest stand ages and soil layers.The N and P contents of the fine roots differed significantly for different stand ages.While their highest values were both found in mature forest,their lowest values were found in middle-aged and pre-mature forest,respectively.2)As the forest grows older,the C/N of fine roots showed a downward trend,and the C/P and N/P normally showed a trend of first increasing and then decreasing.3)The average distribution of fine root biomass and C,N and P storage in soft broad-leaf forests in Guangxi were 7.77～12.26 t/hm2,3 324.18～4 974.21 kg/hm2,44.06～103.36 kg/hm2,7.19～13.62 kg/hm2,respectively.4)The fine root C,N,P storage and biomass of soft-broadleaved forest in Guangxi showed a decreasing trend with the deepening of soil layer and the growth of forest age.Fine root growth in soft-broadleaved forest was generally limited by nitrogen.Nitrogen input should be emphasized in each stand ages of soft-broadleaved forest.
In order to build a green and beautiful Guangdong ecological construction digital twin demonstration area,this articleused point cloud generated tree 3D modeling technology to conduct 1∶1 simulation of the core location trees within the demonstration area.Based on high-resolution stereo image data obtained from oblique photography,a high-precision and standard geographic 3D forest scene was constructed by combining 3D models of trees,buildings,and terrain.At the same time,the Internet of Things data from four intelligent comprehensive monitoring points was connected,and expressed in the virtual 3D forest scene,achieving deep integration between the virtual 3D forest scene and the real forest scene.Combined with the forest growth model,the future state of the forest was simulated,and an immersive interactive digital twin system integrating data collection,model establishment,simulation analysis,and future prediction was constructed.A relatively mature technical systemwas formed through research,providing technical demonstrations and solutions for the construction of a digital twin forestry map in Guangdong Province.
Because of the different purposes and methods of the two monitoring systems,namely the continuous forest resources inventory and forest management inventory,the data of forest resources obtained by the two monitoring systems are inconsistent.In view of this,this paper took Baoding City as an example to carry out analysis and research on the docking scheme of forest stock data between continuous forest resources inventory and forest management inventory.In order to obtain the forest stock information of each county(city and district)in Baoding city,thesubcompartment stock volume prediction model was constructed by using nonlinear index model and tree species groups.The adjustment method was adopted to realize the connection between the continuous inventory of forest resources and the monitoring value of the forest resources planning and design investigation.The results showed as follows:1)the evaluation indexes of the subcompartment stock volume prediction model developed based on tree species groups all performed well,indicating that the model had good prediction ability;2)Compared with the forest management inventory,the forest stockper unit(34.98 m3/hm2)of Baoding City monitored by the subcompartment stock volume prediction modelshowed an accuracy of 91.06％with the monitoring valueof thecontinuous forest resource inventory stock,which greatly reduced the relative error,indicating the reliability of the monitoring value of the subcompartment stock volume prediction model;3)After further adjustment of the model prediction,the connection between the continuous forest resources inventory and forest management inventory was finally realized,indicating the feasibility of the research scheme.The technical scheme studied in this paper can provide technical reference for updating the monitoring data of subcompartment stock volumein all provinces over the years and realizing"one set of data,one piece of map"in the future.
