Above- and belowground responses to nutrient enrichment within a marsh-mangrove ecotone
Above- and belowground responses to nutrient enrichment within a marsh-mangrove ecotone
复制标题
DOI：
10.1016/j.ecss.2020.106884
复制
发表时间：
2020-06
影响因子：
2.8
通讯作者：
C. Weaver;A. Armitage
中科院分区：
文献类型：
--
作者：
C. Weaver;A. Armitage
沼泽和红树林等沿海湿地提供了许多宝贵的生态系统服务，但很容易受到气候变化和人为影响。温带地区以沼泽为主，热带地区以红树林为主；这两种植物类型同时出现在亚热带交错带中。沼泽-红树林生态交错带内的动态可能部分与当地环境驱动因素（如营养富集）有关。先前对单一沼泽和红树林的研究报告称，施肥可提高生产力。然而，成熟植物共生林中多余养分资源的分配尚不清楚。为了研究沼泽-红树林交错带内的养分动态，我们对墨西哥湾内自然共生的互花米草和白骨壤（分别是沼泽和红树林的优势物种）施肥。经过四个生长季节的连续富集后，A 富集小区的地上和地下生物量分别增加了 2.5 倍和 1.5 倍。日耳曼人；S.富集处理之间的互花生物量没有差异。红树林叶子显示出巨大的营养反应，在富集地块中，叶子化学计量发生了改变，表面积更大，SPAD（叶绿素的代表）更大。受精效应可能表明A.相对于 S，germinan 具有更强的获取多余养分并将其分配为生产力和生物量的能力。因此，互花米可能是营养资源的更优竞争者。在单一林分中，沼泽和红树林物种都具有很高的养分吸收潜力，但当它们在沼泽-红树林交错带中共存时，养分保留可能与红树林将养分资源分配为各种地上和地下成分的能力有关。全球气候变化正在推动红树林覆盖向极地延伸至温带盐沼，扩大了沼泽-红树林生态交错带的面积范围。在局部范围内，这些发现表明，人为养分输入可能会加速红树林的扩张。
Coastal wetlands, such as marshes and mangroves, provide many valuable ecosystem services and are vulnerable to climate change and anthropogenic impacts. Marshes are dominant in temperate regions and mangroves within the tropics; both plant types co-occur in subtropical ecotones. Dynamics within marsh-mangrove ecotones may be linked in part to local environmental drivers like nutrient enrichment. Previous studies within monospecific marsh and mangrove stands have reported increases in productivity in response to fertilization; however, the allocation of excess nutrient resources within co-occurring stands of mature plants is not well understood. To investigate nutrient dynamics within the marsh-mangrove ecotone, we fertilized naturally co-occurringSpartina alternifloraandAvicennia germinansstands (the dominant marsh and mangrove species, respectively) within the Gulf of Mexico. After four growing seasons of continuous enrichment, above- and belowground biomass were 2.5 and 1.5 times greater, respectfully, in enriched plots forA. germinans;S. alterniflorabiomass did not differ between enrichment treatments. Mangrove leaves indicated a large nutrient response with altered leaf stoichiometry, larger surface area, and greater SPAD (proxy for chlorophylla) in enriched plots. The fertilization effects may suggestA. germinanshas a greater ability to acquire and allocate excess nutrients into productivity and biomass, relative toS. alterniflora,and may therefore be the superior competitor for nutrient resources. In monospecific stands, both marsh and mangroves species have a high potential for nutrient uptake, but when they are co-occurring in the marsh-mangrove ecotone, nutrient retention may be more linked to mangrove ability to partition nutrient resources into various above- and belowground components. Global climate changes are driving mangrove coverage poleward into temperate salt marshes, expanding the areal extent of marsh-mangrove ecotones. At a local scale, these findings reveal that this mangrove expansion may be accelerated by anthropogenic nutrient input.