南方冬闲稻田杂草群落特征及其生态环境效应分析

Weed Community Characteristics and Their Eco-Environmental Effects in Winter Fallow Rice Fields of Southern China

摘要: 本研究聚焦于南方冬闲稻田杂草群落特征及其生态学效应，采用长期定位施肥试验与田间调查相结合的方法，分析了长期不施肥(CK)、有机肥替代减量化肥(RFC)、常规氮磷钾肥(NPK)三种施肥模式对双季稻冬闲田杂草的种类组成、密度分布、生物量积累及养分固持量的影响。结果表明，在水稻生产过程中，长期不同施肥模式显著影响冬闲稻田杂草的密度、生物量及碳(C)、氮(N)、磷(P)养分固持量。总体而言，冬闲稻田禾本科杂草处于绝对优势地位，其密度占比超过98.0%，而其他种类杂草密度的占比较低，仅为0.5%~1.3%。在杂草总密度方面，RFC和NPK处理较CK处理显著提高了杂草密度(平均为CK的2.7倍)，但显著降低了杂草物种数及物种丰富度指数。冬闲稻田杂草总生物量范围为2139.6~2773.9 kg·ha⁻¹，其中，NPK和RFC处理显著提高了杂草总生物量(约为CK处理的1.3倍)，并显著改变了杂草地上和地下生物量的分配格局，地上部生物量占比超过85.0%。在养分固持方面，冬闲田杂草的C、N、P总固持量分别为827.0~1225.0 kg·ha⁻¹、22.2~32.9 kg·ha⁻¹和2.4~7.3 kg·ha⁻¹；NPK和RFC处理的C、N、P固持量均显著高于CK处理，其中N固持量是CK处理的1.3~1.5倍，P总固持量则达CK处理的2.6~3.1倍。综上，南方冬闲田杂草所产生的生态效应不可忽视，其C、N、P固持量应纳入生态效益评估体系，杂草生物量的增加及其养分固持功能在维系农田生态系统养分循环中具有重要作用。

Abstract: This study investigates the characteristics of weed communities and their ecological effects in winter fallow paddy fields across southern China. Through a long-term localized fertilization experiment combined with field surveys, it examined how three fertilization treatments—no fertilization (CK), reduced chemical fertilizer replaced by organic fertilizer (RFC), and conventional N-P-K fertilizer (NPK)—influence weed species composition, density, biomass accumulation, and retention of Carbon (C), Nitrogen (N), and Phosphorus (P) in double-cropping rice winter fallow fields. The findings revealed that long-term application of different fertilization regimes during rice cultivation significantly influenced weed density, biomass, and C, N, P retention in winter fallow paddy fields. Overall, grass weeds (Poaceae) dominated the community, accounting for over 98.0% of the total weed density, while other weed species had relatively low densities, ranging from 0.5% to 1.3%. In terms of weed density, both RFC and NPK treatments led to a significant increase compared to CK, averaging 2.7 times that of CK, yet they also markedly reduced weed species diversity and the species richness index. The total weed biomass in the winter fallow fields varied from 2139.6 to 2773.9 kg ha⁻¹. The NPK and RFC treatments not only significantly boosted total weed biomass (approximately 1.3 times that of CK) but also substantially altered the allocation pattern between aboveground and belowground biomass, with aboveground biomass accounting for over 85.0%. Regarding nutrient retention, weeds sequestered total C, N, and P amounts of 827.0~1225.0 kg ha⁻¹, 22.2~32.9 kg ha⁻¹, and 2.4~7.3 kg ha⁻¹, respectively. The C, N, and P retention under NPK and RFC treatments were substantially higher than under CK. Specifically, N retention was 1.3~1.5 times that of CK, while total P retention reached 2.6~3.1 times that of CK. In conclusion, the ecological role of weeds in southern winter fallow fields is significant and should not be underestimated. Their capacity for C, N, and P retention ought to be integrated into ecological benefit assessment systems. The increase in weed biomass and its associated nutrient retention function plays a crucial role in sustaining nutrient cycling within farmland ecosystems.