【作者】 王亮；

【导师】 徐小牛；

【作者基本信息】 安徽农业大学 ， 森林培育， 2020， 硕士

【摘要】 为评估全球气候变化对陆地生态系统的影响,在安徽金寨县马鬃岭林场,以不同海拔梯度（一代林:750 m、850 m、1000 m、1150 m;二代林:850 m、1000 m、1150m）杉木（Cunninghamia lanceolata）人工林作为研究目标,采集并测定不同海拔杉木人工林叶片-凋落物-土壤碳氮同位素、养分含量以及各自的土壤物化性质,探讨海拔对杉木人工林叶片-凋落物-土壤碳氮同位素、养分含量以及各自的物化性质的影响,分析叶片-凋落物-土壤各因子对不同形态碳氮同位素分布的控制效应。结果表明:（1）叶片碳氮同位素(δ¹³C、δ¹⁵N)海拔变化显著改变了叶片δ¹³C含量（P<0.05）,一代林当年生叶片对海拔的响应更为明显,随着海拔的增加,叶片δ¹³C呈现波浪式下降趋势。在叶片-凋落物-土壤各林分因子中,通过逐步回归分析筛选出叶绿素b（Chl_b）是影响叶片δ¹³C的主控因子。二代林1年生叶片对海拔的响应更为明显,随着海拔的增加,叶片δ¹³C先增加后降低,在1000 m达到最大值。在林分因子中,叶片厚度（LT）是影响二代林叶片δ¹³C的主控因子。海拔变化显著改变了一代林叶片δ¹⁵N含量（P<0.05）,随着海拔的增加,叶片δ¹⁵N先降低,后增加,在850 m达到最低值。逐步回归分析筛选出土壤含水率在林分因子中是主控因子,二代林叶片δ¹⁵N在海拔上无显著差异（P>0.05）,且无主导影响因子。（2）叶片其它因子一代林只有叶片的干物质含量（LDMC）、叶片全磷（TP）、TN/TP、在海拔上差异显著（P<0.05）,其它因子无显著显著,主成分分析（PCA）可以看出,整个林分叶片因子主要差异在850 m和1150 m海拔之间。二代林中,海拔变化主要改变了叶片全氮（TN）含量、TC/TN以及TN/TP（P<0.05）,PCA分析显示,二代林林分叶片因子差异主要表现在1000 m和1150 m海拔之间。（3）凋落物碳氮同位素海拔变化没有显著改变凋落物的碳氮同位素含量（P>0.05）,但回归分析筛选出全碳（TC）和土壤p H为一代林凋落物δ¹³C主要影响因子,二代林凋落物δ¹³C含量的主要影响因子是凋落物δ¹⁵N和叶片TN;叶片TP是一代林凋落物δ¹⁵N的主要影响因子,叶片叶绿素总量(Chl_a+b)是二代林凋落物δ¹⁵N的主要影响因子。（4）凋落物其它因子凋落物TN和TP在海拔上差异显著（P<0.05）,且均表现在一代林上,二代林各因子在海拔上无显著差异。根据PCA分析结果,一代林主要是750 m和其它三个海拔之间的差异,二代林凋落物养分主要差异在1000 m和850 m。（5）土壤碳氮同位素海拔对土壤碳氮同位素影响均显著（P<0.05）,一代林中,随着海拔的升高,土壤碳氮同位素均表现为随着海拔的升高,δ¹³C和δ¹⁵N均先降低,后升高,在850 m均达到最低值。回归分析筛选出影响土壤δ¹³C的主要因子是叶片LDMC和土壤温度,影响土壤δ¹⁵N的主要因子是土壤TN/TP。二代林中,碳氮同位素均表现为随着海拔的升高而增加,影响土壤δ¹³C的主要因子是土壤温度,影响土壤δ¹⁵N的主要因子是土壤含水率。（6）土壤其它因子海拔变化均显著改变了土壤养分和土壤物化性质（P<0.05）,通过PCA可以看出,一代林土壤因子之间的差异主要表现在850 m和1150 m两个海拔之间,二代林海拔差异主要表现在850 m和1150 m两个海拔之间。更多还原

【Abstract】 In order to to assess the impact of global climate change on plant functional traits in forest ecosystems,the Cunninghamia lanceolata plantation forests across an altitude gradient（first-generation forests:750 m,850 m,1000 m,1150 m;second-generation forests 850 m,1000m,1150 m）were selected in Mazongling Forest Farm in Jinzhai County,Anhui Province.The leaf-litter-soil carbon and nitrogen isotopes,nutrient contents,and their physical and chemical properties of Cunninghamia lanceolata stands were measured,and the controlling effects of leaf-litter-soil factors on the distribution of different forms of carbon and nitrogen isotopes were analysed.The results obtained are as follows.（1）Carbon and nitrogen isotopes in leaves(δ¹³C,δ¹⁵N)The change of altitude significantly affected theδ¹³C content of leaves（P<0.05）.The response of the leaves of the first-generation forest to the altitude is more obvious.As the altitude increased,theδ¹³C of the leaves showed a wave-like downward trend.Among the leaf-litter-soil stand factors,the regression analysis screening out chlorophyll b（Chl_b）was the main controlling factor affecting foliarδ¹³C.The response of the 1-year-old leaves of the second-generation forest to altitude is more obvious.As the altitude increases,the foliarδ¹³C first increased and then decreased,reaching a maximum at 1000 m,and the leaf thickness（LT）was the main control of the foliarδ¹³C in the second-generation forest.The change in altitude significantly changed the foliarδ¹⁵N content in the first-generation forest（P<0.05）.With the increase of the altitude,theδ¹⁵N first decreased,then increased,and reached the lowest value at 850 m.The regression analysis showed that the soil moisture was the main controlling factor.There is no significant difference in the foliarδ¹⁵N in the second-generation forest over the altitude gradient（P>0.05）.（2）Other factors of leavesIn the first-generation forest,only foliar total phosphorus（TP）,total nitrogen/total phosphorus（TN/TP）,and leaf dry matter content（LDMC）had significant differences across the altitude gradient（P<0.05）,and other factors were not significantly different.The principal component analysis（PCA）showed that the main difference in leaf factor was between 850 m and 1150 m.In the second-generation forest,changes in altitude mainly altered the foliar total nitrogen（TN）contents,total carbon/total nitrogen（TC/TN）,and total nitrogen/total phosphorus（TN/TP）（P<0.05）.PCA analysis indicated that the difference in leaf factors in the second-generation stands was mainly between altitude at 1000 m and 1150 m.（3）Carbon and nitrogen isotopes of litterAltitude changes did not significantly change the carbon and nitrogen isotopes of litter（P>0.05）,but regression analysis identified that total carbon（TC）and soil p H were the main factors influencingδ¹³C in the litter of the first-generation forests,and the main effect ofδ¹³C content in the litter in the second-generation forests were litterδ¹⁵N and foliar TN;while the foliar TP was the main factor influencing litterδ¹⁵N for the first-generation forests,and total leaf chlorophyll content(Chl_a+b)was the main factor influencing litterδ¹⁵N in the second-generation forests.（4）Other factors of litterThe litter TN and TP were significantly different over the altitudes in the first-generation forests,while there were no significant differences in the second-generation forests.According to the PCA analysis,the difference between the first-generation forests was mainly between750 m and the other three altitudes,and the main differences in the litter nutrients in the second-generation forests were between altitudes at 1000 m and 850 m.（5）Soil carbon and nitrogen isotopesAltitude had a significant effect on soil carbon and nitrogen isotopes（P<0.05）.In first-generation of forests,as the altitude increased,soil carbon and nitrogen isotopes showed decrease first and then increase,the lowest value was appeared at 850 m.The regression analysis identified that the main factors affecting soilδ¹³C were leaf LDMC and soil temperature,and the main factor affecting soilδ¹⁵N was soil TN/TP.In the second-generation forests,carbon and nitrogen isotopes showed all increase with increasing altitude.The main factor affecting soilδ¹³C was soil temperature,and the main factor affecting soilδ¹⁵N was soil moisture.（6）Other soil factorsAltitude changes significantly altered soil nutrients and soil physicochemical properties（P<0.05）.Through PCA,the differences between soil factors in the first-generation forests were mainly between the two altitudes at 850 m and 1150 m.The difference in altitudes was mainly between 850 m and 1150 m in second-generation forests.更多还原