J Plant Ecol ›› 2020, Vol. 13 ›› Issue (1): 27-35.DOI: 10.1093/jpe/rtz052

• Research Articles • Previous Articles     Next Articles

The role of shaded cocoa plantations in the maintenance of epiphytic orchids and their interactions with phorophytes

Jonas Morales-Linares1,2,3,*, José G. García-Franco1, Alejandro Flores-Palacios2, Thorsten Krömer4, and Tarin Toledo-Aceves1   

  1. 1Red de Ecología Funcional, Instituto de Ecología, A.C., Carretera Antigua a Coatepec 351, El Haya, Xalapa 91070, Veracruz, Mexico, 2Centro de Investigación en Biodiversidad y Conservación, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, Mexico, 3Present address: Centro de Investigación en Biodiversidad y Conservación, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México, 4Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos 44–46, Zona Centro, Xalapa 91000, Veracruz, Mexico
  • Received:2019-01-29 Revised:2019-10-08 Accepted:2019-11-19 Online:2019-11-20 Published:2020-02-01

Abstract:

Aims

Habitat loss and fragmentation are the main threats to biodiversity in tropical forests. Agroecosystems such as shaded cocoa plantations (SCP) provide refuge for tropical forest biota. However, it is poorly known whether the interspecific ecological interactions are also maintained in these transformed habitats. We evaluated the diversity, reproductive status and photosynthetic metabolism (CAM or C3) of the epiphytic orchid community, and their interactions with host trees (phorophytes) in SCP compared to tropical rainforest (TRF).

Methods

In southeastern Mexico, three sites each in TRF and SCP were studied, with four 400 m2 plots established at each site to record all orchids and their phorophytes. We determined the reproductive (adult) or non-reproductive (juvenile) status of each orchid individual in relation to the presence or absence, respectively, of flowers/fruits (or remnants), and assigned the photosynthetic pathway of each orchid species based in literature. We used true diversity and ecological networks approaches to analyze orchid diversity and orchid–phorophyte interactions, respectively.

Important Findings

In total, 607 individuals belonging to 47 orchid species were recorded. Orchid diversity was higher in TRF (19 effective species) than in SCP (11 effective species) and only seven species were shared between the two habitats. CAM orchid species were more frequent in SCP (53%) than in TRF (14%). At the community level the proportion of non-reproductive and reproductive orchid species and the nested structure and specialization level of the TRF orchid–phorophyte network were maintained in SCP. However, only a subset of TRF epiphytic orchids remains in SCP, highlighting the importance of protecting TRF. Despite this difference, shaded agroecosystems such as SCP can maintain some of the diversity and functions of natural forests, since the SCP epiphytic orchid community, mainly composed of CAM species, and its phorophytes constitute a nested interaction network, which would confer robustness to disturbances.

Key words: agroecosystem, ecological networks, Mexico, photosynthetic pathway, tropical rainforest

摘要:
生境丧失和破碎化是热带森林生物多样性的主要威胁。遮荫的可可种植园(SCP)等农业生态系统为热带森林生物群提供了庇护。然而,在这些转化后的生境中是否还维持种间生态的相互作用,目前尚鲜为人知。我们评定附生兰花群落的多样性、繁殖状态和光合代谢(CAM或C3),以及与热带雨林(TRF)相比,它们与SCP中寄主树种(附生植物)之间的相互作用。在墨西哥东南部,对TRF和SCP中各三个采样地点进行研究。每个采样地点建立了4个400平方米的样地,调查记录所有兰花及其附生植物。我们依据花/果实(或残体)是否存在来确定每个兰花个体的繁殖(成体)或非繁殖(幼体)状态,并根据文献确定每种兰花的光合作用途径。我们采用真正的分集和生态网络的方法分别分析兰花的多样性以及兰科与附生植物间的相互作用。我们一共记录了47个兰花种的607个个体。在TRF (19个有效物种)中的兰花多样性高于SCP (11个有效物种),两个生境之间仅共享7个物种。SCP (53%)中的CAM兰花物种比TRF (14%)更常见。在群落水平上,SCP维持了非生殖兰花和生殖兰花的比例以及TRF兰科附生植物网络的嵌套结构和特异化水平。然而,SCP中仅保留一部分的TRF附生兰花,突显出保护TRF的重要性。尽管存在这种差异,诸如SCP类型的遮荫农业生态系统仍然可以维持天然林的一些多样性和功能,因为SCP附生兰花群落主要由CAM物种组成,其附生植物构成了一个嵌套的相互作用网络,对干扰形成了更强的抗性。

关键词: 农业生态系统, 生态网络, 墨西哥, 光合作用途径, 热带雨林