Comparative Study On Ecological Functions Of Chinese Fir Forest And Other Typical Stands In Ecological Public Welfare Forest Area Of Northern Guangdong Province

This paper divides low-yield and low-efficiency Chinese fir forests with other typical broad-leaved pure forests and mixed forests of fir and broad-leaved forests in the ecological public welfare forest area of northern Guangdong.Comparativing analysis of five categories of ecological function indicators,such as accumulating nutrients,conserving soil,conserving water sources,biodiversity conservation and purifying the atmospheric environment.Comprehensive evaluation of ecological functions of different forest types using principal component analysis and fuzzy mathematics.According to the comprehensive evaluation index,comparison of ecological function between low-quality and low-efficiency Chinese fir forests(hereinafter collectively referred to as"Chinese fir forest")and other forest types.Below are key research findings:(1)Comparison of ecological functions between Chinese fir and broad-leaved pure forest.The evaluation indexes of ecological functions of six broad-leaved pure forests are better than those of Chinese fir forest.In general,the ecological functions of broad-leaved pure forests are better than that of Chinese fir forest.There are differences in the evaluation indexes of ecological functions of different pure forests,and the order of size among the indicators is also different.In terms of accumulating nutrients,the carbon storage of Castanopsis hystrix is highest(65.14t/hm~2),and the Cinnamomum campHora is lowest(17.02t/hm~2),the former is 3.7 times that of the latter;the Chinese fir forest is 22.68 t/hm~2,which is only higher than the Cinnamomum campHora forest.The carbon storages of the four pure forests of Castanopsis hystrix,Chinese fir,Michelia chapensis,Michelia macclurei and Cinnamomum campHora era significantly different(P<0.05).In terms of soil conservation,the soil bulk density of Cinnamomum campHora is maximum(1.37g/cm~3),Michelia chapensis is minimum(1.29g/cm~3),the Chinese fir forest is 1.30 g/cm~3,which is at a medium level;the organic matter content of Castanopsi.s hystrix soil is maximum(32.62g/kg),and the Cinnamomum ca;mpHora is lowest(12.07g/kg),the former is 170.3%higher than the latter,the Chinese fir forest is 24.75 g/kg,which is at a medium level.In terms of water conservation,the range of water holding capacity in the field ranged from 369.70 to 289.12 t/hm,and the maximum and minimum values are respectively Michelia macclurei and Schima superba,the field water holding capacity of the Chinese fir forest is lower than that of Castanopsis hystrix and Michelia chapensis and Michelia macclurei and Liquidambar formosana.The effective storage capacity of Castanopsis hystrix litter is biggest(11.33 t/hm),the Cinnamomum campHora is minimum(5.23 t/hm~2),and the maximum value is 2.2 times of the minimum.In terms of biodiversity conservation,the species Cinnamomum campHora of shrub layer and herb layer is the highest,Chinese fir forest is at medium level.In purifying the atmospheric environment,the negative oxygen ion of Michelia.macclurei is highest 881.11/cm~3,and the Chinese fir forest is lowest 255.56/cm~3,the difference between Michelia macclurei and residual forest is significant(P<0.05).(2)Analysis on ecological functions difference of Chinese fir plantations and different mixed forests of Chinese fir and broad.The mixed forest of Chinese fir and broad-leaved forest has obvious effects on improving the ecological function of pure Chinese fir forest,but there are differences in the evaluation indexes of ecological functions among different forest types.In terms of accumulating nutrients,the carbon storage of mixed forest of Chinese fir and Michelia macclurei is biggest(35.51 t/hm~2),and that of mixed forest of Chinese fir and Cinnamomum campHora is smallest(17.02 t/hm~2),the former is twice as much as the latter.There is significant difference between mixed forest of Chinese fir and Michelia macclurei and mixed forest of Chinese fir and Cinnamo,mum campHora and Chinese fir(P<0.05);The carbon stock of Chinese fir plantation is 22.68 t/hm~2,which is only higher than that of mixed forest of Chinese fir and Cinnamomum campHora.In terms of soil conservation,compared with pure Chinese fir forest,the soil organic matter content and total nitrogen content of the mixed forest of Chinese fir and broad-leaved forests are improved to some extent.Indicators for characterizing water conservation capacity,such as capillary water holding capacity,field water holding capacity,and effective interception of litter,have all been improved.The species richness,diversity index and evenness index of shrub layer and herb layer are effectively improved.In purifying the atmospheric environment,the concentration of negative oxygen ions of mixed forest of Chinese fir and Michelia macclurei is the highest(1790.33/cm),and that of Cunningha,mia lanceolata is the lowest(255.56/cm~3),which is 7 times that of the latter,and the concentration of negative oxygen ions in mixed forest of Chinese fir and Michelia macclurei significantly different from other stands(P<0.05).(3)Comparison of ecological functions of Chinese fir plantations in different forest groups.The ecological functions of Chinese fir trees in different age groups are the highest in the near-maturing forests,the lowest in the young forests,and the differences in the ecological function evaluation indexes among different age groups in the accumulation of nutrients,soil conservation,biodiversity conservation and purification of the atmosphere.And the order of the size of each indicator is also different.In terms of accumulation of nutrients,the carbon stock of near-mature forests is 46.20 t/hfm,and that of young forests is 21.89 t/hm~2,and the former is twice the latter,which is significantly different(P<0.05).In terms of soil conservation,the soil pH is less than 4.5,which is a strongly acidic soil;With the increase of age,the soil organic matter content increased,but there is no significant difference in soil organic matter content among different age groups.In terms of water conservation,all soil water retention indicators are the largest in young forests and the lowest in near-mature forests,and the former is significantly different from the latter(P<0.05).In terms of biodiversity conservation,the species rnchness,diversity index and evenness index of shrub layer and herb layer are the largest in the near mature forest.In terms of purifying the atmosphernc environment,the maximum mature forest is 673.33/cm~3,and the young forest is the smallest at 331.11/cm~3.The near-mature forest and the young forest are significantly different(P<0.05).(4)Comprehensive evaluation of ecological functions.The comprehensive evaluation results of ecological functions of different forest types show that among the 13 forest types investigated,the comprehensive evaluation index of mixed forest ecological functions is higher than that of the corresponding pure forests.Among them,the comprehensive evaluation index of mixed forest of Chinese fir and Michelia macclurei is the highest,and the pureest forest of Cinnamomum campHora is the lowest.The order of size is:mixed forest of Chinese fir and Michelia macclurei(2.512)>mixed forest of Chinese fir and Schima superba(1.481)>mixed forest of Chinese fir and Castanopsis hystrix(1.183)>Schima superba(0.839)>Castanopsis hystrix(0.758)>mixed forest of Chinese fir and Michelia chapensis(0.376)>Michelia chapensis(0.223)>Michelia macclurei(0.023)>mixed forest of Chinese fir and Cinnamomum campHora(0.018)>mixed forest of Chinese fir and Liquidambar formosana(0.004)>Mytilaria laosensis(-0.256)>Chinese fir(-1.270)>Cinnamomum campHora(-1.472).The comprehensive evaluation results of ecological functions of Chinese fir trees in different age groups show that the comprehensive evaluation index is the highest in the mature forest(0.569),the middle forest(0.559),and the young forest(0.482).