黄土丘陵区草本群落演替中先锋种群茵陈蒿浸提液的化感作用

为探索自然演替中植被群落结构与化感作用之间的关系,以黄土丘陵区自然演替中先锋种群茵陈蒿为研究对象,通过种子萌发试验,分析演替初期优势种群茵陈蒿浸提液(甲醇浸提液和水浸提液)对自身以及伴生种种子萌发以及幼苗生长的影响,从化学生态学角度解释演替初期群落结构形成的原因。结果表明,茵陈蒿浸提液对3种伴生种(铁杆蒿、白羊草和达乌里胡枝子)的种子萌发均有显著化感作用,低浓度(0.002g/m L)时表现为促进或轻微的抑制作用,高浓度(0.2g/m L)时为较强的抑制作用;不同部位茵陈蒿浸提液的化感作用不同,相比之下,地上部的抑制作用更为强烈,其浸提液均抑制铁杆蒿、白羊草和达乌里胡枝子的种子萌发,尤其在浓度为0.2 g/m L时,达到完全抑制;根系甲醇浸提液对铁杆蒿种子萌发的抑制作用要强于同浓度下的水浸提液,而地上部水浸提液对受体植物根芽的作用大于甲醇浸提液。茵陈蒿对于自身具有一定的抑制作用,表现为高浓度(0.2和0.02 g/m L)的水和甲醇浸提液抑制自身种子萌发和幼苗生长。研究结果说明化感作用可能是该地区在演替前期形成以茵陈蒿为优势种植被群落的重要原因之一。创新点:从化学生态学的角度解释了黄土丘陵区植被演替初期植物之间的关系以及群落结构形成的原因,为认识自然恢复的内在机理提供了新的视角。

Allelopathy of extracts from the pioneer population,Artemisia capillaries, during succession of the herbaceous community in the hilly-gully region of Loess Plateau

It is well-known that allelopathy played an important role in formation of vegetation community the growth of plants by releasing allelochemicals. Previous studies have investigated the relationship between allelopathic effect and plants but these works mainly focused on the agricultural crops; the available information about the effect of allelopathy on the natural vegetation community is scarce. To explore the relationship between the vegetative community structure and allelopathic effects during natural succession, we investigated the effects of water and methanol extracts from Artemisia capillaries, the pioneer population of natural succession on the hilly-gully region of Loess Plateau, on the seed germination and seedling growth for A. capillaries and accompanying species. We aimed to identify an explanation for the vegetative community structure during the early stages of natural succession from the view of chemical ecology. The results showed that A. capillaries extracts had a significant allelopathic effect on the seed germination of three accompanying species, A. sacrorum, Bothriochloa ischaemum, and Lespedeza davurica. Low concentrations of extract (e.g., 2 mg/mL) promoted or slightly inhibited seed germination of the three plants, while high concentrations (200 mg/mL) caused strong inhibition of seed germination. Extracts of different parts of A. capillaries exerted different allelopathic effect on the plants. Compared to the root extracts, extracts from aboveground parts had a stronger influence on seed germination and seedling growth and inhibited the seed germination of A. sacrorum, B. ischaemum, and L. davurica; these effects were most dramatic at higher concentrations of extract (e.g., 200 mg/mL). Receptor plants responded differently to the different extracts. Methanol extracts from the roots of A. capillaries showed stronger inhibition than water extracts of roots on the seed germination of A. sacrorum when applied at the same concentration. However, water extracts from the aboveground parts exhibited stronger inhibition than the methanol extracts of roots on seedling growth. Additionally, a self-allelopathic effect was found in A. capillaries, resulting in inhibition of seed germination and seedling growth when used at 20 or 200 mg/mL. Our findings indicated that allelopathy may be an important factor regulating the formation of the vegetative community in the early stages of natural succession in the hilly-gully region of Loess Plateau, which is dominated by A. capillaries. Our study provided important insights into the formation of the vegetative community on the Loess Plateau and could improve our understanding of the relationship between plants and the mechanism of natural revegetation.