长期施肥对旱地土壤杂草种子库生物多样性影响的研究

为探讨长期施肥对旱地土壤杂草种子库生物多样性的影响,我们在安徽蒙城地区的一个长期肥料试验定位监测点开展了相关研究。采用镜检法对旱地土壤表层（0～15 cm）中土壤杂草种子的种类进行鉴定并计数,记录杂草种子22种,隶属15科。不同施肥处理区杂草种子丰富度以NP1/2K区最高（14.7种）,PK区最低（10.7种）;其中陌上菜（Lindernia procumbens）、栗米草（Mollugo pentaphylla）、醴肠（Eclipta prostrata）、泽星宿菜（Lysimachia candida lindl）四种杂草的种子密度较大,分别在不同的处理区占据优势;从整个试验区来看,烟台飘拂草（Fimbristylis stauntoni）在所有处理中的密度都比较大,处于优势地位。长期不同施肥方式下,农田土壤杂草种子库的物种多样性有显著差异：PK区Shanon-Wiener指数大于其他处理区,但是Simpson优势度指数最低;NPK区Simpson优势度指数最高;PK、CK区Pielou均匀度指数大于其他处理区。田间杂草种子库的群落结构及其物种组成也发生了一定的变化,Whittaker指数表明,与不施肥处理相比较,半量的P和缺N的影响最显著,缺P次之,缺K和平衡施肥则没有显著影响。Sorenson群落相似性指数和Bray Curtis指数聚类分析结果表明,与不施肥相比较,长期施用N、P、K肥能显著改变旱地土壤杂草种子库的组成。本研究表明长期平衡施肥处理更有利于维持和保护旱地土壤杂草种子库的生物多样性。

Influence of long-term different fertilization on soil weed seed bank diversity of a dry land under winter wheat-soybean rotation

The effect of long-term fertilization on biodiversity of weed seed bank in dry land was surveyed in this paper by a field experiment located in Mengcheng experimental station,Anhui province.The weed seed species in top soil（0～15cm） were identified and the quantities were recorded.All seeds were affiliated to 22 species,15 families.Among different treatments,NP1/2K showed the highest seed abundance（14.7 species）,whereas in PK was the lowest（10.7 species）.Seed densities of four species Lindernia procumbens,Mollugo pentaphylla,Eclipta prostrate,Lysimachia candida Linda were higher and dominant in different treatments respectively.It was notable that,seed density of Fimbristylis stauntoni was much higher in all treatments and thus being dominant species in the whole experimental plots.Species diversity in weed seed bank of farmland soil was significantly different between treatments.Shanon-Wiener index in PK was significantly higher than that in any other fertilization treatment,whereas Simpson dominant index was the lowest.The Simpson dominance index in NPK and the Pielou evenness index in PK and CK were the highest in all treatments.A certain of change had also been detected in community structure and species component of weed seed bank.Whittaker index suggested that NP1/2K and CK had the strongest impact on species component of weed seed bank,followed by NK,NP and NPK.Sorenson similarity index and clustering analysis suggested that,comparing with no-fertilization treatment,the long-term application of N,P and K could remarkably change the species component of weed seed bank.The results of this paper showed that long-term balanced fertilization has more advantage for maintaining and protecting biodiversity of weed seed bank in subtropical dry farmland.