Do realignment sites restore microbial biodiversity-driven nutrient cycling and trace gas fluxes comparable to natural coastal ecosystems?

重新排列的盐沼（在以前开发的土地上恢复的盐沼）在英国的沿海管理实践中发挥着重要和日益重要的作用。与天然盐沼生态系统相比，这些管理生态系统具有不同的地上和地下生物多样性和群落结构，这导致了生态系统过程的差异。盐沼在全球气候、养分循环和区域生物多样性方面发挥着重要作用，特别是考虑到它们相对较小的面积（小于地球表面的0.1%）。尽管上游沼泽可能是甲烷（CH4）和氧化亚氮（N2O）的重要来源，但它们据称是重要的碳汇。因此，盐沼可能通过温室气体通量对全球变暖产生多重、可能相互矛盾的影响。盐沼群落还通过产生大量的卤化、含氮和含硫化合物来影响气候，这些化合物影响低层大气和平流层中的臭氧，并充当气溶胶的前体。自然盐沼中这些气候影响过程的生物和非生物驱动因素仍然缺乏了解和/或量化。这种知识的缺乏降低了我们有效模拟未来气候的能力，我们也无法准确评估各种反馈机制（例如全球变暖对盐沼碳储存潜力的影响）对这些过程的影响。自然系统中出现的所有关于生态系统服务、生物多样性和连通性的问题仍然存在于被人类改变的系统中，目前这些问题通常较少被量化，也较少被理解。我们之前的研究已经发现了自然和重组位点之间植物和微生物群落组成的差异。虽然最近的证据表明，这些差异很可能是由当地沉积物的物理和化学差异造成的，而这些差异又由物理过程驱动，但目前还不存在一个普遍接受的、令人信服的解释。这些生物多样性的变化可能导致自然和重新调整的地点之间的功能变化；例如，地下生物多样性似乎受到淹没水中营养（过量）供应以及地上植物群落和根结构的影响。相反，地下群落通过影响碳储量、养分循环速率和释放一些影响气候的微量气体（CH4、N2O、卤代烃和含硫化合物），可以直接或间接地影响地上生物多样性。因此，量化生态系统服务以进行未来气候预测，只有与了解自然盐沼与重新调整盐沼的生物多样性、群落组成和演替的驱动因素相结合，才能最大限度地发挥作用。因此，我们建议从重新排列的盐沼年表中量化微量气体通量，并与当地的自然对应物进行比较。我们与目前已建立的BESS盐沼研究地点的联系意味着我们不会不必要地重复研究重点，但我们将原始提案的意图扩展到沿海社区的一个重要子类别，到目前为止，这些社区的量化或理解都很差。

Realigned salt marshes (restored salt marshes on previously developed land) play a substantial and growing role in coastal management practices within the UK. These managed ecosystems have different above- and below-ground biodiversity and community structures, relative to their natural salt marsh counterparts, which leads to differences in ecosystem processes. Saltmarshes play a large role in global climate, nutrient cycling and regional biodiversity, especially given their relatively small area (<0.1%of the planet's surface). They are purported to be significant carbon sinks, although upper marshes can be substantial sources of methane (CH4) and nitrous oxide (N2O). Saltmarshes may therefore have multiple, potentially conflicting, effects upon global warming through greenhouse gas fluxes. Saltmarsh communities also affect climate by producing significant amounts of halogenated, nitrogen- and sulphur-bearing compounds, which affect ozone in the lower atmosphere and the stratosphere as well as acting as aerosol precursors. The biological and abiotic drivers of these climate-influencing processes within natural saltmarshes remain poorly understood and/or quantified. This lack of knowledge reduces our capacity to effectively model future climate, nor can we accurately assess the implications of various feedback mechanisms (e.g. global warming on saltmarsh carbon storage potential) upon these processes. All of the questions that arise regarding ecosystem services, biodiversity and connectivity in natural systems remain for modified-by-human systems and, at this time, are generally less quantified and more poorly understood. Our prior research has found plant and microbial community compositional differences between natural and realigned sites. A generally accepted, compelling explanation for these differences does not exist although recent evidence suggests that it is likely to be driven by physical and chemical differences in local sediments, which are in turn driven by physical processes. These changes in biodiversity are likely to lead to functional changes between natural and realigned sites; for instance below-ground biodiversity appears to be affected by nutrient (over)supply within inundation waters as well as aboveground plant community and root structure. Conversely, below-ground communities can directly and indirectly affect aboveground biodiversity by their effect on carbon storage, nutrient cycling rates, and their release of a number of climate affecting trace gases (CH4, N2O, halocarbons and sulfur-bearing compounds).Quantifying ecosystem services for future climate projections will therefore be maximally effective only when combined with an understanding of the drivers of biodiversity, community composition, and succession in natural versus realigned saltmarshes. We therefore propose to quantify trace gas fluxes from a chronology of realigned saltmarshes, with comparisons to local, natural counterparts. Our connection to currently established BESS saltmarsh study sites means that we do not duplicate research priorities unnecessarily yet we expand the intent of the original proposal into an important sub-category of coastal communities that are, as of yet, poorly quantified or understood.