Litter‐trapping tank bromeliads in five different forests: Carbon and nutrient pools and fluxes

Abstract

Bromeliads are the most abundant litter‐trapping plants in Neotropical forest canopies. By intercepting litter, bromeliads obtain and retain nutrients before they reach the pedosphere. Here, we analyzed the litter captured and stored by tank bromeliads (TB) in five different forests along an elevation gradient in Mexico. Among those forests, carbon and nutrient pools and nitrogen fluxes in TB were estimated in a mangrove (MF) and a semi‐deciduous tropical forest (SDTF). The composition of the litter trapped by TB along the gradient was similar to forest litterfall and was mainly composed of leaves. Most of the litter was captured in the dry season, and we found a significant effect of projected plant area and the interaction between month and site on bromeliad litter capture. Moreover, litter stored in TB increased exponentially with projected plant area and differed between three studied bromeliad species. In the MF (with ca. 2,700 TB ha−1), barely ca. 1% of annual litterfall is trapped by these plants, but even in the SDTF, with >10,000 TB ha−1, only ca. 2.4% is captured. We found that carbon and nitrogen pools in TB were small and represented <1% of the carbon and nitrogen stored in forest aboveground biomass. Furthermore, the residence time of litter trapped in TB was similar to that of litter on the forest floor. In the light of our results, we conclude that in the studied forests, the effect of TB on the forest carbon and nutrient cycle is negligible. Abstract in Spain is available with online material.

Diversity and putative metabolic function of prokaryotic communities in tank bromeliads along an elevation gradient in tropical Mexico

“…This result indicates that, similarly to soil bacteria across biomes ( Walters and Martiny, 2020 ), tank bromeliads are suitable habitats that contain a high diversity of prokaryotes within a single sample regardless of forest type. In general, tank bromeliads provide nutrient-rich and wet habitats ( Richardson et al, 2000 ; Zotz et al, 2020 ; Aguilar-Cruz et al, 2022 ), where environmental factors can greatly differ depending on the time, plant structure, and position in the canopy ( Laessle, 1961 ; Haubrich et al, 2009 ; Brouard et al, 2012 ; Brandt et al, 2017 ; Giongo et al, 2019 ). Therefore, these tanks offer a large environmental heterogeneity even within forests and promote prokaryotic diversity at a local scale.…”

“…The low predictive power of environmental variables is a common observation in prokaryotic studies in tank bromeliads and suggests that additional unstudied factors, such as biotic interactions, immigration or environmental disturbances, are also important at the community level ( Farjalla et al, 2012 ; Louca et al, 2017b ). Vegetal litter constantly enters the tanks ( Aguilar-Cruz et al, 2022 ) and animals are often in contact with tank water and litter ( Nadkarni and Matelson, 1989 ; Thorne et al, 1996 ; Aguilar-Cruz et al, 2021 ). This was corroborated by the presence of putative animal parasite or symbionts in all samples ( Figure 5B ).…”

“…Many organisms known to perform certain functions may be missing in FAPROTAX, a taxon may be affiliated with multiple functions and functional groups may be nested, for example denitrifying taxa are also associated with nitrate respiration. 1 Moreover, we sampled tank bromeliads that were located on the trunk or inner branches of trees, characterized by a high input of allochthonous organic matter, which is derived mainly from tree litter ( Aguilar-Cruz et al, 2022 ). This was reflected not only in the environmental conditions inside the tanks, with high concentrations of OC, low pH and O 2 , but also in the relative abundance of the putative metabolic functions of prokaryotes.…”

“…1,800 species, representing 60% of this family), and this family is also the most abundant in many Neotropical forest canopies ( Benzing, 2000 ; Zotz, 2013 ; Zotz et al, 2021 ). An outstanding feature of many members of Bromeliaceae (tank bromeliads) is their capacity to capture and store water and litter in tanks formed by their overlapping leaf bases ( Benzing, 2000 ; Zotz et al, 2020 ; Aguilar-Cruz et al, 2022 ). Litter trapped by these plants is subsequently decomposed by associated biota, releasing nutrients that can be absorbed directly from the tank solution via foliar trichomes ( Benzing, 1970 ).…”

“…Until now, bacteria and archaea have been studied mainly in restinga vegetation and Atlantic, lowland, rain and tropical montane forests ( Martinson et al, 2010 ; Pittl et al, 2010 ; Goffredi et al, 2011 ; Carmo et al, 2014 ; Lehours et al, 2016 ; Louca et al, 2017b ; Simão et al, 2020 ). However, there is still a lack of information for other common ecosystems of the Neotropics, such as seasonally dry tropical forests and mangroves, where tank bromeliads can also be abundant ( De Sousa and Colpo, 2017 ; Aguilar-Cruz et al, 2022 ). Moreover, although it is well known that prokaryotic communities differ among and within bromeliad species, comparisons of these communities between ecosystems at a regional scale are still lacking.…”