Sasaki Takehiro, Yoshihara Yu, Takahashi Masaya, Byambatsetseg Lkhagvasuren, Futahashi Risa, Nyambayar Dashzeveg, Suyama Yoshihisa
Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama, 240-8501, Japan.
Graduate School of Agricultural Science, Tohoku University, 232-3, Yomogida, Naruko-onsen, Osaki, Miyagi, 989-6711, Japan.
Oecologia. 2017 Mar;183(3):785-795. doi: 10.1007/s00442-016-3806-z. Epub 2017 Jan 7.
Experiments that simulate nonrandom species loss from natural communities can offer a fundamentally different understanding of the impacts of species loss on ecosystem function and their underlying mechanisms compared to seeding experiments where species are randomly assembled from a local species pool. We examined the mechanisms underlying changes in primary productivity following experimental species loss scenarios in Mongolian grassland. The range of species loss scenarios was based on natural patterns of species abundance that reflect the species' contributions to ecosystem processes. We found a clear reduction in productivity due to species loss only when species were lost randomly. Grassland productivity was relatively robust following nonrandom species loss scenarios. Even in the context of density compensation, the decrease in dominant trait values for leaf height would explain the reduction in productivity with random species loss. In contrast, the maintenance of dominant trait values of key productivity traits such as leaf dry matter content and leaf height might contribute to the maintenance of productivity in response to nonrandom species loss. Our experiment demonstrated that the responses and mechanisms of primary productivity to species loss differ according to the scenarios of species loss in natural grassland communities. The effects of diversity on productivity might be weak in mature natural systems when species loss is nonrandom. Understanding the consequences of realistic species loss on ecosystem functioning based on field-based removal experiments will give insights into real conservation strategies in the face of global biodiversity change.
与从当地物种库中随机组装物种的播种实验相比，模拟自然群落中非随机物种丧失的实验能够从根本上提供对物种丧失对生态系统功能及其潜在机制影响的不同理解。我们研究了蒙古草原实验性物种丧失情景下初级生产力变化的潜在机制。物种丧失情景的范围基于反映物种对生态系统过程贡献的物种丰度自然模式。我们发现，只有当物种随机丧失时，物种丧失才会导致生产力明显下降。在非随机物种丧失情景下，草原生产力相对稳健。即使在密度补偿的情况下，叶高优势性状值的降低也可以解释随机物种丧失导致的生产力下降。相比之下，关键生产力性状（如叶干物质含量和叶高）优势性状值的维持可能有助于应对非随机物种丧失时生产力的维持。我们的实验表明，自然草原群落中初级生产力对物种丧失的响应和机制因物种丧失情景而异。当物种丧失是非随机的时候，在成熟的自然系统中多样性对生产力的影响可能较弱。基于实地去除实验了解现实物种丧失对生态系统功能的后果，将为面对全球生物多样性变化时的实际保护策略提供见解。
