Experimental evidence that the perennial grass persistence pathway is linked to plant growth strategy

Grass species can be classified into different functional types based on their growth strategies, and contrasting persistence strategies are observed in different grass species. Excluding seedling recruitments, changes in populations of grasses are basically a trade-off between natality and mortality of tillers. We hypothesised that the persistence pathway of perennial grasses is linked to their growth strategy, regardless whether they are growing as monoculture or as a mixture. Species with contrasting growth strategies (Arrhenatherum elatius L., Dactylis glomerata L., and Festuca arundinacea Schreb.) were cultivated as monocultures and as a mixture and their tiller natality and mortality were evaluated for two years after swards establishment. All pastures maintained their population size during the experimental period, although decreases in tiller densities occurred during the warmer season. Arrhenatherum elatius had the highest tiller mortality and natality whereas the F. arundinacea had the lowest ones. Arrhenatherum elatius had many tillers appearing in all seasons but their tillers were short-lived. Conversely, F. arundinacea and D. glomerata developed numerous tillers during autumn and winter and their tillers survived, on average, almost six and three times longer than those of A. elatius, respectively. There were no differences in tillering dynamics among populations grown in monocultures or in the mixture. Regardless of whether they were cultivated in monocultures or as a mixture, the persistence pathway of perennial grasses is linked with their growth strategies with exploitative species presenting a high tiller turnover throughout the year whereas the persistence of more conservative species is based on a high tiller survival.

草本植物物种可依据其生长策略划分为不同功能型，且不同草本物种展现出截然不同的存活策略。排除幼苗定植的影响后，草本植物种群的动态变化本质上是分蘖出生率与死亡率之间的权衡关系。本研究提出假说：多年生草本植物的存活路径与其生长策略相关，且该关联不受种植方式（单作或混作）的影响。本研究选取生长策略截然不同的三个物种——（Arrhenatherum elatius L.）、（Dactylis glomerata L.）以及（Festuca arundinacea Schreb.），分别以单作与混作模式种植，并在草地建植后的两年内对其分蘖出生率与死亡率进行评估。尽管在温暖季节分蘖密度有所下降，但所有试验样地的种群规模在实验期间均保持稳定。（Arrhenatherum elatius）的分蘖死亡率与出生率均为最高，而（Festuca arundinacea Schreb.）的两项指标均为最低。（Arrhenatherum elatius）全年均能产生大量分蘖，但这些分蘖的存活寿命较短。与之相反，（Festuca arundinacea Schreb.）与（Dactylis glomerata L.）仅在秋季与冬季产生大量分蘖，且它们的分蘖平均存活时长分别约为（Arrhenatherum elatius）的6倍与3倍。无论以单作还是混作方式种植，各物种的分蘖动态均无显著差异。无论采用单作还是混作模式，多年生草本植物的存活路径均与其生长策略紧密相关：开发型物种全年具备较高的分蘖周转速率，而保守型物种的种群存活则依赖于较高的分蘖存活率。