| In recent years,the climate of Heilongjiang province have also been significantly changed with the global warming and further affected carbon cycling in for forest ecological system. The Heilongjiang forest plays an important role in the carbon budget of Northeast China, therefore, assessment of the effect of climate change on carbon recycling in forest ecological system have been stressed by scientists more and more. However, RS、NPP、NEP were often ignored due to lack of knowledge and difficulties in measuring. This study monitored the precipitation redistribution process of Heilongjiang forest,Through using indigenous IBIS model reconstruction, the present the research simulated annual mean temperature, precipitation, soil respiration, NPP and NEP of Heilongjiang from 1960 to 2100 under SRESA1B instance and further analyzed the space-time dynamics of mean temperature, precipitation, soil respiration, NPP and NEP of Heilongjiang province during three future periods of 2020s (2011～2040)、2050s (2041～2070)、2080s (2071～2100) in 21 century relative to1980s base period.Finally, the effects of climate change on Heilongjiang’s forest ecosystem carbon cycle in the future were analyzed and the main results and conclusions are as follows:Based on Heilongjiang’s actual instance, IBIS model’s dimension, code, figuring and partial parameters were modified and data storage format were also optimize. IBIS model interface operation system was established. The modified IBIS model was verified by comparing actually estimating values of sampling soil and modeling theoretical values.In viewpoint of soil respiration and NPP, the simulation results of modified IBIS modelling is feasible and suitable for carbon cycle prediction of Heilongjiang’s forest.In reference period, the annual mean soil respiration value was 541gC.m2·a-1, In general, the annual mean soil respiration value tends to increase slowly with time, during the period 1980s. According to the annual mean soil respiration value, the whole area was divided into 3 pieces.Among the various climate zones, the highest annual mean soil respiration value(>600 gCm2·a-1) was in the southand; the lowest (<450 gCm2·a-1)was in the Daxing’anling;middle value area was located in the central area.Three time-scales in the future,the annual mean soil respiration value were 583 gCm2·a-1、648 gCm2·a-1、753 gCm2·a-1 respectively.The annual mean soil respiration value was increased from1980s to 2080s,The most relativeincrement rate of the annual mean soil respiration was 15.0 gCm-2/10a,after 2050s the annual mean soil respiration value was on the increase, The most relativeincrement rate was soil respiration value.The spatial pattern of three time-scales soil respiration pattern and growth respiration space similar 1980s, showed high value areas are mainly distributed in the southeast area, such as west in Harbin and south in Shuihua,low value areas mainly distributed in the northeast.In reference period, the annual mean NPP value was 667 gCm2·a-1. In general, the annual mean NPP value tends to decline with latitude during the period 1980s. Among the various climate zones, the highest annual mean NPP value(600 gCm2·a-1) was in the southand; the lowest (200～450 gCm2·a-1)was in the Daxinganling.Three time-scales in the future,the annual mean NPP value were 554 gC.m2·a-1、608 gC.m2·a-1 and 621 gCm2·a-1 respectively. The annual mean NPP value was declined from1980s to 2020s, The most relativeincrement rate of the annual mean NPP was21.4 gCm2·a-1,after 2020s the annual mean NPP value was on the increase, The most relativeincrement rates were 16.8 gCm2·a-1 and 13.8 gCm2·a-1.In the future, Forest NPP in space generally appear that the southeast area was higher, and then gradually to the northwest area to reduce.The annual mean NPP in an area basis along Heilongjiang during 2020s、2050s、2080s periodindicated that southeast area of Harbin increased while Daxinganling area declined.During the period 1961～2100,the annual mean NEP value was 222 gCm-2·a-1, range for-63 gCm-2·a-1 to 361 gCm-2·a-1. In general, forest in heilongjiang province was a carbon sink of forest ecosystem, but carbon sink has a weakening trend.In the future,the annual mean NEP value was 173 gCm-2·a-1 and the forest ecosystem was a relatively weakly carbon sink during the period 2020s. on the other hand, the forest ecosystem was a strongest carbon sink during the period 2020s.Among the vegetation types. In the future, the annual mean NEP value in space generally appear that the southeast area was higher, and then gradually to the northwest area to reduce. Southern forest showed a stable carbon sink in four periods,but Daxinganling showed frequently changes between carbon source or carbon sinks.According to SRESA1B climate scenario, the Heilongjiang climate shows variability and a significant positive trend in temperature and precipitation during the period 1961～2100 (except in 2020s). Climatic conditions during 2020s-2080s will been warmer and drier than 1980s normal at whole study area. On the average, mean temperature in Heilongjiang increases by 5.5℃during 1980s～2080s, whereas precipitation increases by only about 15%, except in 2020s precipitation decreased 15% compared to1980s. The changes in temperature and precipitation are not spatial uniform. The Heilongjiang temperature CV shows variability from 0.1% to 6.5% during the period 1961-2100. and precipitation CV varied 2.2%～14.5%.On the average, mean temperature CV and precipitation CV in Heilongjiang were 2.9% and 6.2%. precipitation CV varied more than temperature CV during the period 1961 ～ 2100. The distribution of average NPP、NEP、soil respiration derived by IBIS during the period of 1980s to 2080s, indicating strong spatial gradients which reflect gradients in temperature and precipitation conditions. If adding the same CV between temperature and precipitation, precipitation was more important than temperature about NEP and soil respiration. NPP was just the opposite.For the three scenarios, mean soil respiration value、mean NPP value、mean NEP value are expected to see decline by 4.43%,5.69%,15.89% under Aclimate change scenarios and mean soil respiration value、mean NPP valueshow an increasing tendency with the largest increment value of 6.83% and 7.64% under the C climate change scenarios. Mean soil respirationand NPP shows an increasing tendency with the value of 4.07% and 1.49% under the B climate change scenarios but mean NEP of Heilongjiang shows an decline tendency with the value of 6.2 %.Among the three scenarios of climate changes in future,sensitivity of soil respiration to precipitation and the temperature is high, there is a positive correlation between the precipitation, low sensitivity to the changeof temperature.NPP increases sensitivity to precipitation and the temperature, but the correlation changes with temperature fluctuation is not strong, the precipitation of high sensitivity. NEP was significant negative correlation, correlation with temperature fluctuation is not strong, positive relationship with precipitation, especially drought stress, may lead to forest ecosystems by carbon into carbon source. |
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