灌枝覆盖和氮添加对荒漠草地土壤理化性质及牛枝子叶功能性状的影响

Effects of shrub shelter and nitrogen addition on soil physicochemical properties and leaf functional traits of Lespedeza potaniniiin desert grassland

摘要:

【目的】 研究覆盖和氮添加下荒漠草地土壤理化性质和豆科植物叶功能性状以及它们之间的关系，有助于提高豆科植物生长发育，为改善荒漠草地的植物生长提供有效的管理措施。【方法】 以灌木柠条（Caragana intermedia）的枝条为覆盖材料，设4种覆盖模式为主区，即灌枝覆盖样地面积的 0% （F0）、30% （F30）、50% （F50）和70% （F70）；设置4种尿素添加处理为副区即N0 [0 g/（m2·a） ]， N10[10 g/（m2·a） ]，N20[20 g/（m2·a） ]，N40[40 g/（m2·a）]，测定了土壤理化性质和牛枝子（Lespedeza potaninii）叶功能性状。【结果】 随着覆盖的增加，土壤水分提高，土壤温度降低，有机质含量呈现先增加后降低的趋势，以F30最高；速效磷和全磷含量分别在F30、F50较F0相比均下降，但覆盖对土壤pH和碱解氮无显著影响。氮添加总体上会降低土壤水分和pH值，提高碱解氮、速效磷、全磷的含量，对土壤温度和全氮无影响。与F0相比，覆盖会显著增加牛枝子叶长、叶宽以及叶面积。相同覆盖处理下叶绿素含量和比叶面积随氮添加量增大而增加，而叶面积和F70处理中叶宽随氮添加量增大均减小。氮添加对不同覆盖下叶长和长宽比无影响。相关分析表明叶长、叶宽以及叶面积与土壤温度呈负相关，与土壤含水量和pH呈正相关。此外，叶绿素与土壤pH值呈负相关，与碱解氮呈正相关，碱解氮还与比叶面积呈正相关。【结论】 灌枝覆盖改善了土壤水分条件，利于牛枝子叶片的生长。而氮添加不利于叶片的增大，但有助于提高叶片叶绿素含量，从而提高了植物光合速率以及对资源的获取能力。

Abstract:

【Objective】 To study the effects of shrub shelter and nitrogen addition on soil physicochemical proper ties and leaf functional traits of legumes in desert grassland and their relationships，it is helpful to improve the under standing of the growth and development of legumes，and provide effective management measures for improving plant growth in desert grassland.【Method】 Therefore，we used shrub caragana as the sheltering material，and set up four covering modes，namely 0% （F0，no branches），30% （F30），50% （F50） and 70% （F70）. The four nitrogen supple mental levels were 0 g/（m2·a） （N0），10g/m2a （N10），20 g/（m2·a） （N20），and 40 g/（m2·a） （N40）.【Result】 With the increase of mulch，soil moisture increased，soil temperature decreased，organic matter content increased first and then decreased，and F30 was the highest；The content of available phosphorus and total phosphorus decreased in F30 and F50，respectively，compared with that in F0，but soil pH and alkali-hydrolyzed nitrogen were not signifi cantly affected by mulching. N addition can decrease soil moisture and pH，increase the content of alkali-hydrolyzed nitrogen，available phosphorus and total phosphorus，and has no effect on soil temperature and total nitrogen. Com pared with F0，mulching significantly increased cotyledon l ength，leaf width and leaf area. Under the same mulch，the chlorophyll content and specific leaf area increased with the nitrogen addition，while the leaf area and the middle width of F70 treatment decreased with the nitrogen addition. Nitrogen addition had no effect on leaf length and length‐width ratio under different mulch. According to correlation analysis，leaf length，leaf width and leaf area were negatively cor related with soil temperature，and positively correlated with soil water content and pH. In addition，chlorophyll was negatively correlated with soil pH，positively correlated with alkali-hydrolytic nitrogen，and positively correlated with specific leaf area.【Conclusion】 Irrigated branch mulching improved the soil water condition and was beneficial to the growth of the leaves of bough. The addition of nitrogen is not conducive to the growth of leaves，but helps to in crease the chlorophyll content of leaves to improve the photosynthetic rate and resource acquisition ability of plants.