5.2.3. Tank Epiphyte Ecosystems
Tank Epiphyte Ecosytems (i.e. the communities of organisms contained within and associated with tank bromeliads) represent a unique ecological solution to intercepting and impounding rainwater in a landscape devoid of surface water. Particularly in many bromeliad species, the rosette leaf arrangement causes rainwater and leaves falling from the canopy to be funneled towards the leaf axils, where they are collected in " tanks" or " cisterns" that can contain several litres of water. These pools of water, known as phytotelmata, are of great importance as permanent water resources, particularly during the dry season. In Cockpit Country, tank bromeliads support the foundation of the food web. Organisms associated with these breeding pools include protozoans, rotifers, crustaceans, insects, and amphibians.

Tank Epiphyte Ecosytems depend upon the availability of substrates to support a gradient of size classes (e.g., large tree branches to support large individual bromeliads) and a gradient of abiotic (e.g., precipitation and sunlight regimes) and biotic (e.g., fall of leaves) factors (Table 7). For example, individual plants at different sites will acquire varying amounts of leaf litter from the canopy. In general, plants growing at shaded sites will accumulate larger amounts of leaf litter i.e., the allochthonous input is relatively high. In such detritus-based food webs, bacteria will play a major role. In contrast, in unshaded sites, the input of leaf litter is much lower and, lacking canopy cover, the tank is exposed to light. Accordingly, here algae play a major role in food webs and, consequently, species composition is significantly different from the assemblages found in shaded tanks.

The biodiversity health of Tank Epiphyte Ecosystems was judged to be " VERY GOOD" by the experts (Table 2). Despite the reduction of Wet Limestone Forest from its historic size and the removal of late-succession, large stage classes of trees (see Table 8), the functional integrity of Tank Epiphyte Ecosystems is believed optimal i.e., the target is functioning at an ecologically desirable status and requires little human intervention. Species turnover, however, has been observed in recently cleared cockpit bottoms and hillslopes. Similar to the Wet Limestone Forest target, experts were concerned about the disruption of connectivity between forest blocks in the landscape and the effects on cross-pollination and dispersal of propagules such that the landscape context was rated " GOOD."