Litter Product Dynamics and Nutrient Returns of Typical Returning Farmland to Bamboo Plantation in the Mountainous Region of Southern Sichuan | 川南山丘区典型退耕竹林凋落物产量动态与养分归还

chinois. 以麻栎次生林和杉木人工林为对照,研究四川长宁山丘区硬头黄竹林、毛竹林、苦竹林3种典型退耕竹林凋落物的生产模式、年产量动态、周转时间与养分归还。结果表明：硬头黄竹林与杉木人工林凋落物月产量动态为双峰模式,毛竹林与苦竹林凋落物月产量动态为左偏单峰模式,麻栎次生林凋落物月产量动态呈现右偏单峰曲线;退耕竹林凋落物年均产量都高于对照林分,排序为硬头黄竹林（5.87 t・hm-2）〉苦竹林（5.47 t・hm-2）〉毛竹林（4.56 t・hm-2）〉麻栎次生林（4.46 t・hm-2）〉杉木人工林（1.93 t・hm-2）;凋落物周转时间排序为杉木人工林（2.77 a）〉苦竹林（2.19 a）〉硬头黄竹林（2.09 a）〉毛竹林（1.72 a）〉麻栎次生林（0.43 a）;3种退耕竹林凋落物大量元素N,P含量均低于对照林分,K含量以麻栎次生林最高,杉木人工林最低,竹林凋落物Si含量显著高于对照林分;麻栎次生林大量元素（N,P和K）归还量最多（117.43 kg・hm-2）,杉木人工林最低（31.59 kg・hm-2）,3种竹林微量元素（Si,Ca和Mg）归还量均高于对照林分,养分总归还量排序为硬头黄竹林（382.55 kg・hm-2）〉苦竹林（295.00 kg・hm-2）〉麻栎次生林（179.11 kg・hm-2）〉毛竹林（142.33 kg・hm-2）〉杉木人工林（53.36 kg・hm-2）;川南山丘区退耕竹林虽具有较强的自肥能力,仍可选择麻栎等乡土阔叶树种混交,并增加N,P和K肥施入,以加快凋落物周转和养分归还。

anglais. With Quercus acutissima secondary forest（ Ⅳ） and Cunninghamia lanceolata plantation（ Ⅴ） as controls,we investigated the litter production patterns,dynamics,turnover time and nutrient returns of three typical returning farmland to bamboo forests,including Bambusa rigida（ Ⅰ）,Phyllostachys edulis（ Ⅱ） and Pleioblastus amarus forest（ Ⅲ）,in the mountainous region at Changning county,Sichuan Province. The result showed： A bimodal pattern was fitted to litter productions of Ⅰ and Ⅴ,a left-skew monomodal pattern to Ⅱ and Ⅲ,and a right-skew monomodal pattern forⅣ. Annual average litter yields of the three bamboo forests were higher than those of Ⅳ and Ⅴ,with a rank of Ⅰ（ 5. 87t・hm- 2） Ⅲ（ 5. 47 t・hm- 2） Ⅱ（ 4. 56 t・hm- 2） Ⅳ（ 4. 46 t・hm- 2） Ⅴ（ 1. 93 t・hm- 2）. The turnover time of forest litters was in the order of Ⅴ（ 2. 77 a） Ⅲ（ 2. 19 a） Ⅰ（ 2. 09 a） Ⅱ（ 1. 72 a） Ⅳ（ 0. 43 a）. The litter N and P contents in the three bamboo forests were lower than those of Ⅳ and Ⅴ,and the Si content was significantly higher than the controls. The K content was highest in Ⅳ and lowest in Ⅴ. The macro-element returns of N,P,and K was highest inⅣ and lowest in Ⅴ,and they were 117. 43 and 31. 59 kg・hm- 2,respectively. The micro-element returns of Si,Ca,and Mg in the three bamboo forests were all higher than those in Ⅳ and Ⅴ. For different forests,moreover,the total nutrient returns followed the sequence of Ⅰ（ 382. 55 kg・hm- 2） Ⅲ（ 295. 00 kg・hm- 2） Ⅳ（ 179. 11 kg・hm- 2） Ⅱ（ 142. 33kg・hm- 2） Ⅴ（ 53. 36 kg・hm- 2）. Although there exists relatively self-fertilizing ability in the bamboo forests,they should be mixed with some broadleaf trees,such as Q. acutissima,for supplying N,P and K to promote litter turnover and nutrient return.