基于网孔分解袋法的荒漠草原柠条枯落物分解过程中的养分变化

Detection of changes in litter nutrients in Caragana korshinskii following the decomposition process in desertified grassland ecosystems using the litter bag method

以宁夏荒漠草原柠条(Caragana kornshinskii)枯落物为研究对象,采用网袋分解法(4、2和0.01mm),研究了不同大小柠条灌丛(极小型Ⅰ、小型Ⅱ、中型Ⅲ、大型Ⅳ)下微生境枯落物分解过程中养分质量残留率变化特征。结果表明,1)分解至210d时,N、K元素在3种网孔内均呈现释放状态,而P元素和纤维素在3种网孔内均呈现富集状态。木质素仅在0.01mm网孔内的大型灌丛微生境中呈富集状态,而在极小型、小型和中型灌丛微生境中呈释放状态。2)在Ⅱ类、Ⅲ类和Ⅳ类灌丛微生境中,枯落物养分元素残留率表现为3种网孔间均无显著差异(P>0.05)。但是在Ⅰ类灌丛微生境中,N、P和K元素残留率均表现为0.01mm(-32.99%、121.03%、-2.04%)>4mm(-63.64%、14.31%、-6.95%)>2mm(-75.47%、9.79%、-36.32%),木质素残留率表现为0.01mm(-10.56%)>2mm(-46.18%)>4mm(-49.59%),而纤维素残留率表现为2mm(160.44%)>4mm(97.80%)>0.01mm(21.56%)。研究表明,在宁夏荒漠草原地区,3种网孔分解袋内不同大小柠条灌丛微生境中枯落物N、K、P元素和纤维素变化规律均相似,而木质素受到土壤动物类群分布和柠条灌丛大小的双重影响。

An investigation of the elemental nutrient residual rate of Cartagena korshinskii shrub litter was conducted using the litter bag method (4,2,0.01 mm) in Yanchi County,Ningxia.The results showed: 1) At 210 days,there was a "release" of litter N and K,whereas there was an "accumulation" of litter P and cellulose in C.korshinskii shrub litter within litter bags with three size meshes.Regarding lignin,there was an "accumulation" in the large shrub microhabitats,whereas there was a "release" in the microhabitats with very small-,small-,and medium-sized shrubs in the 0.01 mm mesh litter bags only.2)There were no significant (P > 0.05) differences in residual rate in the litter between three types of meshes in the microhabitats of small,medium,and large-sized shrubs.In the microhabitats of very small-sized shrubs,however,the residual rate of litter N,P,and K was in the order of 0.01 mm (-32.99%,121.03%,-2.04%)> 4 mm (-63.64%,14.31%,-6.95%)> 2 mm (-75.47%,9.79%,-36.32%),that of lignin was 0.01 mm (-10.56%)> 2 mm (-46.18%)> 4 mm (-49.59%),and that of cellulose was 2 mm (160.44%)> 4 mm (97.80%)> 0.01 mm (21.56%).It was concluded that there were similar changes in litter nutrient elements N,K,P,and cellulose in microhabitats of very small,small,medium,and large shrubs in all three mesh sizes.However,there were interactive effects of soil faunal groups and shrub canopy sizes on litter lignin following the decomposition process in desertified grassland ecosystems of Ningxia.