| Forest productivity is a fundamental parameter for assessing the structure and function of forest ecosystems across various scales.Forest productivity can be affected by climate,site conditions and human disturbance,which shows obvious spatio-temporal variability and complexity.It is of great significance to clarify the temporal and spatial variation of forest productivity to reveal the service maintenance mechanism of forest ecosystem and to carry out sustainable management of forest.P.massoniana,one of the most widely distributed afforestation species in China,plays an important role in maintaining regional ecological security and forest stock growth.Although many studies have focused on P.massoniana productivity and its response to environmental changes at different scales,the temporal and spatial variability of productivity in north subtropical P.massoniana forests under the influence of climate and human activities and the complexity of its key driving mechanisms remain to be further studied.To solve this problem,the temporal and spatial variation characteristics of productivity and biomass of P.massoniana plantation in Hubei province were studied in this study to reveal the temporal and spatial variability of productivity and the complexity of driving factors of productivity of P.massoniana plantation in north subtropical areas,so as to provide a basis for in-depth understanding of productivity and ecosystem service maintenance mechanism of P.massoniana plantation.The research takes the P.massoniana plantation in Hubei Province as the research object.Based on the basic data such as the continuous inventory of forest resources in Hubei Province from 1994 to 2014 and the regional long-term climate observation data,using methods such as spatial interpolation analysis and correlation analysis to study the spatio-temporal variability characteristics of the long-term（1972-2014）regional climate change in Hubei Province,quantitatively study the spatio-temporal variability characteristics of biomass accumulation and productivity of P.massoniana plantations,and evaluate P.massoniana based on the interaction between plantation productivity and key environmental factors,explore the production zoning of P.massoniana plantation in Hubei Province.The main results of this study are as follows:（1）Temperature and precipitation in Hubei province have significant spatiotemporal variation characteristics.From 1972 to 2014,the annual average temperature of Hubei Province showed a significant upward trend（p<0.01）,and the annual average temperature change rate was 0.257℃·（10a）-1.The annual precipitation showed a downward trend,but the change was not significant（p>0.05）.The annual variation of monthly average temperature and monthly precipitation in Hubei Province for many years both showed obvious single-peak characteristics,and the peaks appeared in July,the rain-heat synchronization feature is obvious.From 1972 to 2014,the annual average temperature of Hubei Province was0.5-19.1℃（The province average value 15.0℃）,with obvious spatial differentiation.The average annual temperature in the western mountains is lower,and the average annual temperature is higher in the Wuhan urban area.The average annual temperature in the east is increasing.The multi-year average annual precipitation in Hubei Province is 791.1-1781.8mm（the average annual precipitation is 1267.6mm）,with obvious spatial variability.The high precipitation areas are distributed in southwest and southeast Hubei,and the low precipitation areas are concentrated in northwest Hubei.The regional trend of significant changes in the annual average temperature in Hubei Province for many years is(-0.22～0.55℃·（10a）-1,p<0.05),accounting for 89.39%of the total area of Hubei Province.The temperature increase trend in Wufeng County is large and significant,and the temperature in Zigui County is lowered,and the trend is significant.The significant changes in annual precipitation are concentrated in Lichuan City(-5.70～-3.69 mm·（10a）-1,p<0.05),and the area ratio is only1.25%.（2）The biomass of P.massoniana plantation in Hubei province was positively correlated with the age of the plantation（5-49a）,and the power function fitting effect of biomass change with time was the best.The model formula is:ln（Y）=0.836ln（X）+2.779（where Y is stand biomass,X is stand age,R2=0.419,p<0.01）.The spatial variability of the productivity of the P.massoniana forests of different ages is obvious.The productivity of the 15-year-old P.massoniana forest is 0.26-5.38 t·hm-2·a-1(the average value of the province is 1.57 t·hm-2·a-1),and the productivity of the 25-year-old P.massoniana forest is 0.20-5.47 t·hm-2·a-1(the provincial average is 1.61 t·hm-2·a-1),while the 35-year-old P.massoniana forest productivity is 0.37-4.69 t·hm-2·a-1(the provincial average is 1.96 t·hm-2·a-1);the productivity of15-year-old,25-year-old and 35-year-old P.massoniana forests all showed high productivity areas mainly in southwestern Hubei.The spatial distribution characteristics of the productivity of 15-year-old and 25-year-old P.massoniana plantations are similar,but the area of high productivity of 35-year-old P.massoniana forests shifted from southwest Hubei to northwest Hubei.（3）The precipitation in September,the average monthly temperature from April to July,and the average temperature during the growing season all have significant effects on the productivity of the 15a,25a,and 35a P.massoniana forests（p<0.05）,but the main factors affecting the productivity of the P.massoniana plantations in the three age stages is difference:15-year-old P.massoniana forest productivity is mainly negatively correlated with the average temperature in July（p<0.05）,and significantly positively correlated with the high stand density（p<0.05）;25-year-old P.massoniana is mainly negatively correlated with the average temperature in April（p<0.05）,and significantly positively correlated with the high stand density（p<0.05）;35-year-old P.massoniana is mainly positively correlated with altitude（p<0.05）.（4）Based on the productivity of 20a P.massoniana plantation,the spatial distribution characteristics of P.massoniana plantation in Hubei province were determined.The key environmental factors affecting the spatial variation of productivity of the 20a P.massoniana plantation were mean temperature,slope and soil layer thickness in April.This study divided the P.massoniana forest production in Hubei Province into two grades,including three primary production areas（class I,II,and III production areas）and 8 secondary production areas.Among them,the productivity of 20-year-old P.massoniana forests in I-1 Pingshan and Qingjiang watersheds areas was the highest,mainly distributed in southwestern Hubei,and the productivity of 20-year-old P.massoniana forests in III-4 Jianghan Plain and Mufu Mountain areas was the lowest,mainly distributed in southeastern Hubei.In general,the productivity of P.massoniana plantations in Hubei Province has obvious temporal and spatial variability.August precipitation,September precipitation,October precipitation,annual average temperature,average growth season temperature,the monthly average temperature in each growing season,the number of plants in hectares,the altitude,the thickness of the soil layer and the humus layer,and other factors,which may be lead to north subtropical of P.massoniana plantation productivity variation of time and space,the main factors and changing with forest age,P.massoniana plantation productivity of key environmental factor and its strength is also the variation.Therefore,on the basis of zonal management of P.massoniana forest,it is necessary to consider the variation of key environmental impact factors in different forest age stage,and adopt targeted management strategies in combination with the actual situation,so as to improve the productivity of P.massoniana plantation. |
PDF Full Text Request