Nurse Effects Of Adult Plant To Seedlings Under Soil Acid Stress

The plant-plant interactions include both competition and facilitation. The net outcome of plant-plant interactions could be changed from competition to facilitation as the environmental stress increases. The facilitation between plants, therefore are often applied to the restoration of degraded habitat. The establishment of seedlings is one of the important stages of regeneration of plant populations under stress environment. Thus, understanding how adult plants can facilitate their neighboring seedlings under stress environment is important in restoration ecology. Here, I conducted a greenhouse-controlled experiment and a field experiment to study the nurse effects of adult plant on seedlings under soil acid stress by using Lespedeza formosa Koehne as a nurse plant. The results are as follows.1 Species differ in tolerant to acid soilResults from the greenhouse-controlled experiment showed that the growth of plant species indicating by germination rate, seedling survival rate, plant height, plant capony and biomass significantly differed in responding to soil acidity. Amorpha fruticosa L. had strong tolerance to acid stress, while Indigofera pseudotinctoria Matsum showed moderate tolerance. Trifolium repens L., Cynodon dactylon (L.) Pers., Lolium perenne L. and Festuca arundinacea Schreb. were weak in tolerance to soil acidity.2 The nurse effects of adult plant on seedlings under soil acidity gradientThe nurse effects of adult plant on neighboring seedlings were significantly different along the soil acidity. As the soil acidity decreased (pH=4.1,5.6 and 6.9), the relative interaction index (RII) values of A. fruticosa did not change and was close to 0. For I. pseudotinctoria, the RII values shifted from negative to positive. For T. repens, C. dactylon, L. perenne and F. arundinacea, however, the RII values shifted from positive to negative.3 Adult plants facilitating the formation of arbuscular mycorrhizae in the roots of neighboring seedlingsMolecular analysis showed that arbuscular mycorrhizal fungi (AMF) communities in the roots of target plants A. fruticosa and I. pseudotinctoria were similar to the roots of adult plant L. formosa, indicating that adult plant may promote AM formation in the roots of its neighboring seedlings. Results also showed that AMF colonization rates in roots of target seedlings I. pseudotinctoria and C. dactylon were significantly higher with adult neighbor than without neighbor.