In the pole forests of the Rio Tapiche-Blanco, Peru

As part of our ongoing research on understanding the distribution and dynamics of Peruvian peatlands, I spent part of July with a IIAP-St Andrews-Edinburgh team exploring the floodplain of the Rio Tapiche and its tributary, the Rio Blanco.

Thinly-spaced pole forest near the Rio Blanco
Pole forest near the Rio Blanco
IIAP research boat “Tornillo II” moored in the seasonally flooded forest at the start of a day’s fieldwork.

The Tapiche is a right-bank tributary of the Ucayali, in the south of the Pastaza-Marañón Basin. It’s not exactly remote – our field sites are around eight hours by speedboat from Nauta – but there are only half a dozen small communities between the little service port of Requena and the headwaters of the Blanco, and essentials, especially fuel, are hard to come by. IIAP’s research boat, the Tornillo II, was near its limit with six on board plus food for a week, gasoline and all our sampling equipment.

The logistical pains paid off as we set out to collect field data to test and refine our predictions about the distribution of carbon stored in peat. Gratifyingly, everywhere we thought we would find peat, we did. Our field days involved arriving at a pre-defined point at the river bank, cutting a rough trail through the (usually non-peaty) seasonally-flooded forests bordering the river, then working inland as far as we could within the time constraints of the 12-hour tropical day. Along the way we took samples and recorded the characteristics of the vegetation and soils. This season we are using a combination of the rapid survey techniques we have used in the past, and a more comprehensive inventory that takes a couple of hours for the team to complete (but is still quicker than the four to seven days it takes to set up a permanent census plot).

Sampling peat in the Rio Blanco basin

These techniques are helping us to see nuances in the vegetation that we were not so aware of in the past. Along the Blanco we saw many variations on what the team is now thinking of as ‘jiiri’ – an Urarina word (see our recent publication here) that refers to all ‘open’ peatlands, where ‘open’ can mean anything from totally lacking trees, to a fully closed tree canopy made up of short, thin trees (a ‘varillal’ or ‘pole forest’). It’s becoming clear to us that these environments are very variable, forming a gradient (or several gradients) of varying canopy height, stem density, and canopy openness. There seem to be big differences too in the importance of flooding, and in the character of the substrate (though we have always, so far, found peat underneath them).

Dense pole forest
Pole forest showing clear flood marks

Floristic and geochemical data will hopefully provide a more solid description and functional understanding of these various environments, as will palaeoecological analysis (the chosen topic of PhD student Dael Sassoon). In the medium term, this understanding of how different ecological units inter-relate will help us to understand how and where carbon is stored in the peaty soils of the western Amazon.

We were very generously hosted and assisted in our work by the community of Nueva Esperanza.

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