Abstract. Amazonian peat swamp forests remove large amounts of carbon dioxide (CO2) but anaerobic decomposition of the peat produces methane (CH4). Drought or cultivation cuts down on the CH4 production but may increase the CO2 emission. Varying oxygen content in nitrogen-rich peat produces nitrous oxide (N2O). Despite the potentially tremendous changes, greenhouse gas emissions from peatlands under various land uses and environmental conditions have rarely been compared in the Amazon. We measured CO2, CH4 and N2O emissions from the soil surface with manual opaque chambers, and environmental characteristics in three sites around Iquitos, Peru from September 2019 to March 2020: a pristine peat swamp forest, a young forest and a slash-and-burn manioc field. The manioc field showed moderate peat respiration and N2O emission. The swamp forests under slight water table drawdown emitted large amounts of CO2 and N2O while retaining their high CH4 emissions. Most noticeably, a heavy shower after the water-table drawdown in the pristine swamp forest created a hot moment of N2O. Nitrifier denitrification was the likely source mechanism, as we rule out nitrification and heterotrophic denitrification. We base the judgement on the lack of nitrate and oxygen, and the suppressed denitrification potential in the topsoil. Overall, our study shows that even moderate drying in Peruvian palm swamps may create a devastating feedback on climate change through CO2 and N2O emissions.

Se evaluó la supervivencia e insectos plaga de especies forestales y frutales en Puerto Almendra, Loreto, Perú. Se obtuvieron plántulas y estacas de 15 especies forestales y de 04 especies frutales, a partir de poblaciones naturales y huertos familiares; estas fueron instaladas en parcelas de 25 x 25 m, 25 individuos por especie. Las estacas de Spondias purpurea tuvieron mayor supervivencia (84%), Spondias mombin y Spondias dulcis alcanzaron 36% y 24% respectivamente. Las plantas provenientes de semillas botánicas con muy buena supervivencia (80‑100%) fueron Copaifera paupera, Dipteryx odorata, Carapa guianensis, Swietenia macrophylla, Hura crepitans, Chorisia integrifolia, Spondias mombin, Guazuma ulmifolia, Pleurothyrium parviflorum, Amburana cearensis. Con buena supervivencia (60‑79%) se encuentran Cedrelinga cateniformis, Cedrela odorata y Genipa americana. En la categorı́a regular (40‑59%) están Caryodendron orinocense y Calycophyllum spruceanum. En la categorı́a malo (<40%) Calophyllum brasiliense y Aniba rosaeodora. Se revisaron minuciosamente los daños de los insectos en las plantas, 04 plagas fueron registradas: Hypsipyla grandella en S. macrophylla, C. odorata y G. ulmifolia con incidencia de entre 100% y 84%; Parasaissetia nigra tuvo una incidencia de 88% en G. ulmifolia; Apioscelis bulbosa fue encontrada en G. ulmifolia, C. integrifolia, S. purpurea y S. dulcis con incidencias del 80, 56, 8 y 4% respectivamente y Aphis gossypii fue registrada en S. purpurea con 20% de incidencia. Esta investigación proporciona información orientada a la propagación, manejo y conservación de especies forestales y frutales de la Amazonı́a peruana.

&lt;p&gt;Peatlands are an enormous sink of carbon and nitrogen. Natural and human disturbances may release them as greenhouse gases (GHGs) or water pollutants. Tropical peatlands have especially intensive matter cycling. Amazonia holds almost a half of tropical peatlands. Most of it is inaccessible to current forestry and drainage machinery and thus untouched by man. Tropical rainforest has been labelled &amp;#8217;lungs of the Earth&amp;#8217;. While photosynthesis in mature forests does sequester carbon in biomass, they respire an equal amount of carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;). Only swamp forests may sequester carbon in wet anoxic peat for centuries. However, anoxic decomposition of peat yields methane (CH&lt;sub&gt;4&lt;/sub&gt;) and suboxic processes release nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O). Both have high global warming potential. In undisturbed peatlands, carbon sequestration outweighs GHG emissions. GHG budgets are more complicated in disturbed peatlands.&lt;/p&gt;&lt;p&gt;With an objective to clarify the greenhouse gas budget of tropical peatlands, the Department of Geography, University of Tartu held a measurement campaign in Iquitos, Peruvian Amazon in September 2019. We observed fluxes of the three GHGs using opaque chambers and measured potential environmental factors in three sites under various disturbance histories: 1) a Mauritia flexuosa palm-dominated swamp forest, 2) toe-slope swamp forest grown in 12 years on fallow pasture and banana plantation, and 3) slash-and-burn cassava field.&lt;/p&gt;&lt;p&gt;The toe-slope swamp respired the largest amounts of CO&lt;sub&gt;2&lt;/sub&gt; while site differences were small and may have been offset by photosynthesis (which we did not measure). The wet swamp forest sites, especially palm trunks, emitted large amounts of CH&lt;sub&gt;4&lt;/sub&gt;. The dry slash-and-burn cassava field emitted little methane. The CH&lt;sub&gt;4 &lt;/sub&gt;emissions were strongly correlated with nitrogen content of the peat. Previous literature links high soil nitrogen content with lability of soil organic carbon and high microbial activity. The swamp forest floor emitted an average of 390 &amp;#181;g N&lt;sub&gt;2&lt;/sub&gt;O-N m&lt;sup&gt;&amp;#8211;2&lt;/sup&gt; h&lt;sup&gt;&amp;#8211;1&lt;/sup&gt; after torrential rainfall. The downpour may have carried just enough oxygen into the peat to trigger N&lt;sub&gt;2&lt;/sub&gt;O production by nitrification or hamper the full pathway of denitrification to N&lt;sub&gt;2&lt;/sub&gt;. High peat Ca&lt;sup&gt;++&lt;/sup&gt; and Mg&lt;sup&gt;++&lt;/sup&gt; content and pH&gt;4 favoured nitrification. High NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;-N concentration in the swamp peat (190 mg kg&lt;sup&gt;&amp;#8211;1&lt;/sup&gt;), which can be related to N&lt;sub&gt;2&lt;/sub&gt; fixation and litter from three species of leguminous trees, formed a solid base for nitrification. The slash-and-burn cassava field emitted a sizable 37 &amp;#181;g N&lt;sub&gt;2&lt;/sub&gt;O-N m&lt;sup&gt;&amp;#8211;2&lt;/sup&gt; h&lt;sup&gt;&amp;#8211;1&lt;/sup&gt;. In conclusion, the variety of disturbances produced an interesting pattern of GHG emissions in relationship with environmental conditions. Thus, Amazonian peatlands demand elevated attention.&lt;/p&gt;