While in Palo Verde last summer, I met Ramsa Chaves, a graduate student at Dartmouth College under Brad Taylor and UCR licenciatura graduate. She used the OTS station in Palo Verde as a headquarters for her research on insect communities associated with streams in the Guanacaste region. Her and one or more assistants traveled to local streams that varied in surrounding land-use and sampled emergent insects during the day, returning to sort and process the catch in PV in the evening. I helped out one of those days to get a taste of her extraordinary and ambitious research project. From memory, Ramsa aimed to examine responses of insect communities to land-use differences and how these responses play-out in aquatic-terrestrial linkages.
We sampled two streams that she and Jereme had set traps in and around three days prior. In Quebrada Amores (lovers stream) within Reserva Biológica Lomas de Barbudal emergence traps were emptied. The floating, triangular traps, as suggested by their name, capture adult insects as the emerge from the stream to breed and feed in the surrounding terrestrial environment.
Río Pijije drains agricultural and residential land, in contrast to the protected, forested land-use surrounding Quebrada Amores. Emergence traps had settled ashore after a flash flood, and were not sampled, a common occurrence in the rainy season in dry forest areas. Sticky traps (transparent over-head sheets covered in glue, basically) were placed from 10 to 100 m from the stream edge to sample flying insects as they moved from the stream outward into the the forest or, in this case, cow pasture. In addition to sticky traps, we sampled using butterfly nets, which are not pictured here (probably for two reasons (1) I was sampling and (2) I knocked my net into a large paper wasp next and was promptly stung many, many times. It was an extremely memorable event for me). Both sampling methods have hopefully painted a picture for Ramsa showing how insects respond from and to a stream draining catchment with different land-use patterns.
Although these were taken during different experiments, the poles remain in the same positions and the height that the photographs were taken was the same – my height. The water depth and vegetation are strikingly different.
Croton argenteus confused me for a while. I had encountered the species in and around the Palo Verde wetland as a small, emergent plant, and had assumed it was annual or at least without above ground tissue across years because it was not present in the beginning of the season and it was flowering soon after emerging. As such, I could not find it in the keys….
Then, while driving to Reserva Biologica Lomas de Barbudal to help Ramsa (a PhD student studying watershed land-use effects on insect communities in and around dry-forest streams), I spotted a large shrub that looked surprisingly similar to my yet unidentified wetland plant. When I returned and picked up the shrub and tree book – bingo.
I suspect that cattle grazing knocks back this species from growing to a shrub-like state, since there is frequently evidence of herbivory on the small plants I encountered.