Biodiversität und Klima Forschungszentrum (LOEWE BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany.
PLoS One. 2013 Apr 29;8(4):e61149. doi: 10.1371/journal.pone.0061149. Print 2013.
Aboveground and belowground biomass compartments of vegetation fulfil different functions and they are coupled by complex interactions. These compartments exchange water, carbon and nutrients and the belowground biomass compartment has the capacity to buffer vegetation dynamics when aboveground biomass is removed by disturbances such as herbivory or fire. However, despite their importance, root-shoot interactions are often ignored in more heuristic vegetation models. Here, we present a simple two-compartment grassland model that couples aboveground and belowground biomass. In this model, the growth of belowground biomass is influenced by aboveground biomass and the growth of aboveground biomass is influenced by belowground biomass. We used the model to explore how the dynamics of a grassland ecosystem are influenced by fire and grazing. We show that the grassland system is most persistent at intermediate levels of aboveground-belowground coupling. In this situation, the system can sustain more extreme fire or grazing regimes than in the case of strong coupling. In contrast, the productivity of the system is maximised at high levels of coupling. Our analysis suggests that the yield of a grassland ecosystem is maximised when coupling is strong, however, the intensity of disturbance that can be sustained increases dramatically when coupling is intermediate. Hence, the model predicts that intermediate coupling should be selected for as it maximises the chances of persistence in disturbance driven ecosystems.
植被的地上和地下生物量部分履行不同的功能，并通过复杂的相互作用耦合在一起。这些部分交换水、碳和养分，地下生物量部分具有在地上生物量被食草动物或火灾等干扰去除时缓冲植被动态的能力。然而，尽管它们很重要，但根系-茎叶相互作用在更启发式的植被模型中经常被忽略。在这里，我们提出了一个简单的两部分草地模型，它将地上和地下生物量耦合在一起。在这个模型中，地下生物量的生长受到地上生物量的影响，地上生物量的生长受到地下生物量的影响。我们使用该模型来探讨草原生态系统的动态如何受到火灾和放牧的影响。我们表明，在地上-地下耦合的中等水平下，草原系统最具持久性。在这种情况下，系统可以承受比强耦合更强的极端火灾或放牧制度。相比之下，系统的生产力在高耦合水平下达到最大值。我们的分析表明，当耦合很强时，草原生态系统的产量达到最大值，但是，当耦合处于中等水平时，系统可以承受的干扰强度会显著增加。因此，该模型预测，中间耦合应该被选择，因为它最大限度地提高了在受干扰驱动的生态系统中持续存在的机会。
