草地灌溉对土壤性质和植物物种组成的影响

Exploration of the response of soil properties and plant species composition to centuries-old traditional meadow irrigation

草地是欧洲范围内生物物种最为丰富的动植物栖息地之一;为了对大面积的草地开展有效的保护,必须要采取具有针对性和可持续性的管理措施。虽然如今大都已被弃用,但传统上的灌溉却有可能是一种具有可持续性的管理策略。然而,对于一般的湿润性生态区域,人们还不太了解灌溉、土壤特性以及植物物种这3者之间的相互影响。我们旨在将传统的草地灌溉对植物群落的影响从传统的低施肥量效应中分离出来,从而获得植物生态学方面的新知识。我们的考察对象是植物的组成和多样性以及它们与土壤特性(有机态碳、总氮、持水性/保水力、中型土壤动物活力)和土壤养分(无机态氮、磷、钾、镁、硼)指标之间的潜在联系。在田间研究中,我们对过去长期灌溉的13块草地以及未经灌溉的13块草地(其中17块草地经过施肥,9块未经施肥)进行了比较。分析这些草地在一整年时间内的植物多样性和物种组成情况以及土壤养分和土壤特性指标,并且假设不同年份之间的差异不大。研究结果发现,灌溉和施肥使土壤特性和土壤养分发生了改变,但它们对植物物种多样性并无影响,只影响植物的物种组成。淤积土具有更细的粒度,因而拥有更高的保水力和养分储量。因此,需要获取水分和养分资源的禾本科植物在经过灌溉的草地上占据优势。本研究的结果表明,对于中欧地区大量的已开发草地,灌溉不仅能保护其生物多样性,而且还有可能使其植物具有不同的植物功能性状。

Only targeted and sustainable management will preserve extensively managed grasslands,one of Europe’s most species-rich habitats.Traditionally,largely abandoned irrigation might prove a sustainable management strategy,but the understanding of the interactions among irrigation,soil properties and plant species are low for a generally humid ecoregion.We aimed at advancing our understanding of plant ecology by disentangling plant community responses to traditional lowland meadow irrigation from traditionally low fertilization rates.We studied plant composition and diversity jointly with the underlying links to soil properties(Corg,total N,water holding capacity and mesofaunal activity)and soil nutrients(Nmin,P,K,Mg and B).In a field study,we compared 13 long-term traditionally irrigated and 13 non-irrigated(17 fertilized and 9 non-fertilized)meadows.We surveyed plant diversity,composition and soil nutrients as well as soil properties for 1 year assuming low annual variation.Irrigation and fertilization led to differences in soil properties and soil nutrients without impact on sheer plant species diversity but on plant species composition.Finer grain sizes due to siltation increased water holding capacity and nutrient storage.Hence,resource-acquisitive graminoid species had advantages in irrigated meadows.Thus,irrigation is not only a mean to preserve biodiversity of extensively used meadows of Central Europe but may prove a tool to differentiate between plant functional traits.