人为干扰对猕猴桃园杂草多样性与土壤因子关系的影响

Effect of human disturbance on relationship between weed species diversity and soil factors in kiwifruit orchards

【目的】探讨人为干扰条件下猕猴桃园杂草多样性与土壤因子的关系,为制定合理的生态控草措施及保障果园绿色生产提供科学依据。【方法】分别设置对照和干扰样地,测定样地群落α-物种多样性指数和土壤化学指标,并利用冗余分析、典范对应分析和回归分析探讨“化学除草+人工除草”干扰对园内杂草多样性与土壤因子耦合关系的影响。【结果】(1)5个对照样地共记录杂草15科24属25种,5个干扰样地共记录杂草14科18属19种,菊科、禾本科杂草丰富度较高;对照、干扰样地各自的4项多样性指数之间均无显著差异,但干扰使优势杂草由本土种稗转变为入侵种喜旱莲子草。(2)冗余分析显示,多样性指数与土壤pH呈负相关,且干扰使pH对杂草多样性的主导作用进一步增强;干扰样地中,速效磷与Simpson优势度指数(R^(2)=0.957,P=0.042)、Pielou均匀度指数(R^(2)=0.989,P=0.010)之间均呈显著的“先上升后下降”二项式拟合关系。(3)典范对应分析显示,干扰加剧了杂草的斑块化聚集分布,使决定杂草物种分布的主导因子由pH、速效钾转变为速效磷、硝态氮,且导致诸多杂草对硝态氮产生趋避行为;典范对应分析排序图中,马唐、龙葵均与喜旱莲子草的位置相接近。【结论】通过土壤改良保持较高pH及速效磷含量、利用果园生草技术种植抗逆性强的本土种以应对喜旱莲子草入侵、及时拔除喜硝杂草均有助于猕猴桃园杂草防控提质增效。

【Objective】The study aimed to explore the relationship between weed diversity and soil factors in kiwifruit orchards under artificial disturbance,providing reference for formulating the accurate ecological weed control measures and ensuring the green production in orchards.【Method】The control and disturbed plots were set up.Theα-species diversity indices and soil chemical indicators of these plot communities were measured,and the methods of redundancy analysis,canonical correspondence analysis and regression analysis were used to examine the effect of‘herbicide+manual weed control'disturbance on the coupling relationship between weed species diversity and soil factors.【Result】(i)The 25 weed species belonging to 15 families and 24 genera were recorded from five control plots,while 19 weed species belonging to 14 families and 18 genera were recorded from five disturbed plots,and the Asteraceae and Poaceae had the higher species richness.There was no significant difference in the four diversity indices between control and disturbed plots,however,the dominant weed changed from the native species Echinochloa crusgalli to the invasive species Alternanthera philoxeroides under disturbance.(ii)The redundancy analysis showed that the diversity indices had a negative relationship with soil pH,and disturbance further enhanced the determinant of pH on weed diversity.In disturbed plots,soil available phosphorus had a significant binomial fitting relationship with Simpson dominance index(R^(2)=0.957,P=0.042)and Pielou evenness index(R^(2)=0.989,P=0.010),which all showed the convex trend.(iii)The canonical correspondence analysis showed that disturbance exacerbated the patchy aggregation distributions of weeds,and caused the determinants of weed distributions changing from soil pH and available potassium to available phosphorus and nitrate nitrogen,and led to an avoidance behavior of many weed species to the increasing nitrate nitrogen.In the canonical correspondence analysis diagram,the Digitaria sanguinalis and Solanum nigrum were all close to A.philoxeroides.【Conclusion】Maintaining a higher pH and available phosphorus content through soil improvement,planting native plants with strong resistance to prevent A.philoxeroides invasion through orchard grasses cultivation,and timely eradicating the nitrate nitrogen-preferred weeds are all beneficial for improving the quality and efficiency of weed control in kiwifruit orchards.