松材线虫侵染的马尾松人工林细根形态及生物量分异特征

中龄林的马尾松受松材线虫侵染后,林木生长、生理生化指标、群落多样性等会发生异质性变化,但是,针对患病林木地下细根的响应尚不清楚。本研究以松材线虫疫区患病马尾松和健康马尾松为研究对象,采用土柱法,分0-15 cm和15-30 cm土层,对细根进行分级研究,定量分析1-5级细根的形态、生物量以及养分元素,探讨松材线虫侵染的马尾松人工林细根形态、生物量以及养分元素的分异特征。结果表明:(1)患病马尾松人工林细根的健康状态与根长密度、生物量呈极显著正相关(P<0.01),低级根(如1级根)患病后,响应会更加强烈。(2)马尾松人工林患病后,细根有效磷、速效钾浓度会显著降低(P<0.05),而全氮、钙浓度会显著升高(P<0.05)。(3)松材线虫病使林分的土壤有机质含量显著高于健康林分(P<0.05),而土壤速效钾含量会显著低于健康林分(P<0.05)。以上结果表明,松材线虫侵染的马尾松人工林会在细根形态、细根养分和土壤养分上会发生特异性响应,揭示了松材线虫病对马尾松人工林地下细根的影响,旨在为松材线虫病防治提供一定参考。

Morphology and biomass differentiations of fine roots in Pinus massoniana plantation infected by Bursaphelenchus xylophilus

Pinus massoniana plantation is an important part of forest resources in China. Its construction has greatly increased forest coverage and solved the contradiction between wood supply and demand. But a large number of Pinus massoniana plantations are easy to be infected with pine wood nematodes (PWN), Bursaphelenchus xylophilus, heterogeneous changes have taken place on the forest growth, physio-biochemical indexes, community diversity, etc. At present, little is known on the underground response, especially the response of the infected Pinus massoniana fine roots to the pine wood nematode disease. In this study, the infected Pinus massoniana plantation and healthy plantation were sampled by the soil column method at the pine wood nematode epidemic area, and the soil layer was divided into 0-15 cm layer and 15-30 cm layer. The fine root morphology and biomass were quantified in level 1-5 root orders to further understand the heterogeneous changes of the fine root morphology, biomass and nutrient concentration. Ultimately, this study would like to explore the differential characteristics of the fine root morphology, biomass and nutrient elements of the Pinus massoiniana plantation infected by the pine wood nematodes. The results showed that: (1) The health status of the infected Pinus massoniana plantation fine roots was positively correlated with the root length density (RLD) and biomass (P<0.01). The low order fine roots, such as level-1 roots, would respond more strongly after the fine roots were affected by the pine wood nematode disease. (2) When the Pinus massoniana plantation were attacked by the pine wood nematodes, the concentrations of the infected fine root available phosphorus and available potassium were significantly decreased (P<0.05), while the concentrations of total nitrogen and calcium were significantly increased (P<0.05). (3)The pine nematode disease also influenced the soil crucial components that the soil organic matter content of the infected Pinus massoniana plantation was significantly higher than that of the healthy stand (P<0.05), while the content of the soil available potassium was significantly lower than that of the healthy Pinus massoniana plantation (P<0.05). The above results firstly showed that heterogeneous changes happened on the infected Pinus massoniana plantation of the fine root morphology, root nutrient concentration and soil nutrient concentration. The Pinus massoniana plantation responded to the pine wood nematode disease on the underground by the fine roots. Furthermore, the effect of the pine wilt disease (PWD) on the fine roots of the infected Pinus massoniana plantation was revealed, aiming to provide some reference for the prevention and control of the pine wilt disease on Pinus massoniana plantation.