亚热带常绿阔叶林凋落物生产及其养分含量对模拟氮沉降的响应

发布时间：2018-07-24 15:04

【摘要】：森林凋落物是森林生态系统中物质循环和能量流动的一个主要环节,是森林生态系统功能过程的重要组成部分。在安徽省石台县通过对天然常绿阔叶林进行模拟氮沉降试验:对照(CK,0 kg·hm-2·a-1)、低氮(LN,50 kg N·hm-2·a-1)、高氮(T1,100 kg N·hm-2·a-1)、高氮+磷(T2,100 kg N·hm-2·a-1+50 kg P·hm-2·a-1),研究林内凋落物数量、组成及其养分等季节动态,经过一年的实验观测,研究得到初步结论如下。1.凋落物量不同水平模拟N处理样地的年凋落物量总量有所不同。甜槠林四种处理的年凋落量分别是:CK,7.19 t·hm-2·a-1、LN,8.85 t·hm-2·a-1、HN,8.77 t·hm-2·a-1和HN+P,9.41 t·hm-2·a-1,LN、HN、HN+P处理均一定程度上增加了凋落物量。苦槠林三种处理的年凋落量分别是:CK,7.86 t·hm-2·a-1、HN,9.21 t·hm-2·a-1和HN+P,8.84t·hm-2·a-1,三种处理亦均增加了凋落物产量。各模拟N沉降处理年凋落物产量均落入亚热带森林年均凋落量范围之内(3.0~14.44 t·hm-2·a-1),说明凋落物量具有一定的地带性。2.凋落物组分凋落物各组分大小顺序为:叶枝花果杂质。这和祁门亚热带常绿阔叶林不同凋落物各组分及其占总凋落量的比例存在一定差异,叶凋落量在各处理中都占有绝对优势。3.凋落特征甜槠林与苦槠林均具有明显的凋落节律,季节动态均为双峰型。一个高峰发生在雨季刚开始的4月,另一个高峰发生在11月,凋落量最少出现在3月。不同模拟N处理处理凋落高峰期有差异。其中叶的凋落特征与总量的凋落特征相似,说明叶在凋落物中占有主导地位。与对照相比,经施肥处理后,凋落特征并未发生显著变化。4.凋落物养分主要元素年均含量大小顺序为:NKCaMgP,且落叶中养分含量最高。LN、HN、HN+P处理均增加了凋落物N含量。在落叶中,各营养元素季节动态性较强。在甜槠林,凋落物的N年归还量分别为:CK,55.77、LN,64.44、HN,62.60、HN+P,69.08 kg·hm-2;P年归还量分别为1.73、2.10、2.07、2.33 kg·hm-2;K年归还量分别为34.72、39.11、39.96、40.23 kg·hm-2;Ca年归还量分别为38.55、46.49、40.67、40.89 kg·hm-2;Mg年归还量分别为26.23、34.64、30.12、30.98 kg·hm-2。三种处理均增加了主要元素的年归还量,大小顺序为LNHN+PHNCK。苦槠林中,凋落物N的年归还量分别为:CK,58.27、HN,70.74、HN+P,65.42 kg·hm-2;P年归还量分别为2.71、3.67、3.02 kg·hm-2;K年归还量分别为36.89、49.48、43.52kg·hm-2;Ca年归还量分别为48.97、52.86、49.45 kg·hm-2;Mg年归还量分别为23.73、24.92、21.89 kg·hm-2。施肥处理同样增加了N、P、K、Ca、Mg的年归还量。大小顺序为HNHN+PCK。5.凋落物各组分C/N比与对照相比,不同处理各组分C/N比值均有下降。说明经过模拟氮沉降处理后,N含量明显提高,引起C/N比值下降。
[Abstract]:Forest litter is a main link of material circulation and energy flow in forest ecosystem, and it is an important part of forest ecosystem function process. Simulated nitrogen deposition experiments were carried out in natural evergreen broad-leaved forest in Shitai County, Anhui Province. The seasonal dynamics of litter amount, composition and nutrient were studied by means of CK 0 kg hm-2 a-1, low nitrogen 50 kg N hm-2 a-1, high nitrogen (T1100 kg N hm-2 a-1), high nitrogen and phosphorus (T2100 kg N hm-2 a-1 50 kg P hm-2 a-1). After one year of experimental observation, the preliminary conclusions are as follows. 1. The amount of litter in different levels of simulated N treatments is different in the total amount of litter per year. In Castanopsis carlesii forest, the annual litter amount was 7.19 t hm-2 ~ (-1) LN ~ (1), 8.85 t / a ~ (-1) hm-2 ~ (-1) hm-2 a ~ (8.77 t) hm-2 a ~ (-1) and 9.41 t hm-2 ~ (-1) HNN P, respectively, which increased the litter amount to a certain extent. In Castanopsis carlesii forest, the annual litter amount was 7.86 t hm-2 / a ~ (-1) HNN 9.21 t hm-2 a ~ (-1) and 8.84 t / a ~ (-1) hm-2 a ~ (-1) respectively, and the litter yield was also increased by the three treatments. The annual litter yield of each simulated N deposition treatment fell within the range of annual litter amount of subtropical forest (3.0 ~ 14.44t hm-2 ~ (-1), which indicated that litter yield had a certain zonality. 2. The order of litter components was as follows: leaf branch, flower and fruit impurity. There were some differences between different litter components and their proportion to total litter in Qimen subtropical evergreen broadleaved forest, and leaf litter had absolute advantage in all treatments. Both Castanopsis eyrei forest and Castanopsis eyrei forest have obvious rhythm of litter, and the seasonal dynamics are both bimodal. One peak occurred in April, the start of the rainy season, and the other peak occurred in November, at least in March. The peak period of litter was different in different simulated N treatments. The characteristics of leaf litter were similar to that of total litter, indicating that leaf played a dominant role in litter. Compared with the control, the litter characteristics did not change significantly after fertilization. 4. The average annual content of main nutrient elements in litter was in the order of: (1) NKCaMgP, and the highest nutrient content in litter was. LNN (HNN) HN P treatment increased the N content of litter. In the deciduous leaves, the seasonal dynamics of each nutrient element is strong. In Castanopsis carlesii forest, the annual return amount of litter was 55.77kg / hm-2K, respectively. The annual return amount of litter was 64.44.44 (HNN) 62.60m ~ (-1) HN ~ (69.08) kg 路m ~ (-2) P = 1.732.10 ~ (2.33) kg 路hm ~ (-2) K, respectively. The annual return quantity of litter was 34.72C ~ (39.119.9N) ~ (40.23) kg 路h ~ (-2) Ca = 38.555.46.46.46.46.46.46.46.7N ~ 40.89 kg 路h ~ (-2) mg, respectively. The annual return quantity of litter was 26.233.644 ~ (30.1230.98) kg 路h ~ (-2) mg 路m ~ (-2) 路m ~ (-1) 路h ~ (-1) 路h ~ (-2) K ~ (-1). Each of the three treatments increased the annual return of the main elements in the order of LNHN PHNCK. In Castanopsis carlesii forest, the annual return amount of litter N was 58.27% HNN 70.74 kg / hm ~ (-2) P was 2.71 ~ (3.67) kg 路hm ~ (-2) K ~ (-1), respectively. The annual return amount of litter N was 36.89999.49.43.52kg / h ~ (-2) Ca ~ (-1) = 48.97m ~ (52.86.45) kg 路hm ~ (-2) mg = 23.733N 24.922289 kg 路hm ~ (-2) 路hm ~ (-2), respectively. The annual return of mg was also increased by fertilization. The order of size is HNHN PCK.5. Compared with the control, the C / N ratio of different treatments decreased. The results show that after simulated nitrogen deposition, the content of N increases obviously, which results in the decrease of C / N ratio.
【学位授予单位】：安徽农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S714

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