Tropicalization of the barrier islands of the northern Gulf of Mexico: A comparison of herbivory and decomposition rates between smooth cordgrass (Spartina alterniflora) and black mangrove (Avicennia germinans)

the expansion of black mangrove avicennia germinans into historically smooth cordgrass spartina alterniflora-dominated marshes with warming temperatures heralds the migration of the marsh-mangrove ecotone northward in the northern gulf of mexico. with this shift, avicennia is expected to outcompete spartina where it is able to establish, offering another prevalent food source to first order consumers. in this study, we find avicennia leaves to be more preferable to chewing herbivores, but simultaneously, chewing herbivores cause more damage to spartina leaves. despite higher nitrogen content, avicennia leaves decomposed slower than spartina leaves, perhaps due to other leaf constituents or a different microbial community, for other studies have found the opposite in decomposition rates of the two species’ leaf tissue. this study provides insights into basic trophic process, herbivory and decomposition, at the initial stages of black mangrove colonization into spartina salt marsh.

随着气温的升高，黑红树属植物银叶树（Avicennia germinans）向历史上由光滑荻草（Spartina alterniflora）主导的湿地扩张，预示着墨西哥湾北部湿地-红树林生态过渡带向北迁移。伴随这一转变，银叶树有望在能成功建立的地方击败荻草，为初级消费者提供另一种常见的食物来源。在本研究中，我们发现银叶树叶片更受咀嚼性食草动物的青睐，然而，咀嚼性食草动物对荻草叶片的破坏也更严重。尽管银叶树叶片含有更高的氮含量，但其分解速度却慢于荻草叶片，这或许是由于叶片的其他成分或其他微生物群落的差异，因为其他研究在两种物种叶片组织分解速率方面发现的结果恰好相反。本研究对黑红树属植物在荻草盐沼地初始殖民阶段的营养过程、食草和分解的基本原理提供了洞见。