Tropical Rainforest

In 1990 the U.S. Naval Medical Research Center Detachment (NMRCD) initiated a clinic-based surveillance program to determine the etiologies of febrile illness in Iquitos, Peru [10] (link)–[12] (link). In 2000 NMRCD collaborated with local Ministries of Health to expand the surveillance program into other regions of Peru and South America, including sites in Ecuador, Bolivia, and Paraguay. In addition to Iquitos, in 2000 the study was implemented at regional sites in or near Piura, Cusco, Tumbes, and Yurimaguas, Peru, as well as Santa Cruz, Bolivia (Figure 1; Table 1). Additional sites were later added in Concepción, Magdalena, and Cochabamba (Villa Tunari and Eterazama), Bolivia; Guayaquil, Ecuador; Asunción, Paraguay; and La Merced and Puerto Maldonado, Perú. Participants were recruited when reporting with acute febrile illness to public, private, or military health facilities in and around these regional centers. Details of the study sites are described in Table 1. Study sites were selected based largely on locations in hot and humid climates conducive for arbovirus transmission, typically situated near or in tropical rainforest regions. Notable exceptions include Piura, Tumbes, and Cusco, which are located in coastal desert (Piura and Tumbes) or highlands (Cusco; Figure 1 and Table 1) regions. It should be noted that the study staff in Cusco (Hospital Regional) on occasion attended to participants arriving from surrounding highlands rainforest regions.

The MFT of each location was obtained by calculating the mode of daily mean temperature distributed in the 54^th–92^th range during the entire year, which is the 95% distribution of the MMPs. We systematically analysed the distribution of the MMTs, annual mean temperature, 78^th percentile temperature and MFTs in 420 locations from 30 countries. We compared the two existing indicators (annual mean temperature and 78^th percentile temperature) and the new indicator (MFT).
We applied a MLR model to fit the MMT according to the seven independent variables. The model is defined below (Equation (1)): $y=\alpha +\sum _{i=1}^7{\beta }_i{x}_i$ where y is the MMT, α is the intercept. x₁,…x_i (i = 1,…,7) are the independent variables in Table 1, and β₁,…β_i (i = 1,…, 7) are the regression coefficients.
We mapped the error (Equation (2)) histograms of the above three temperature indexes and calculated the Pearson correlations among them and the MMT. $Error=∣T-MMT∣$ where T refers to the three temperatures mentioned above.
The 420 locations in the present study covered eight of the 11 major climatic zones, (including tropical grassland, tropical monsoon, tropical rainforest, subtropical monsoon, temperate continental, temperate maritime, temperate monsoon, and Mediterranean climates, excluding for the tropical desert, plateau mountain, and cold climates). We combined eight climatic zones into three categories: temperate climate (including 91 locations), subtropical climate (including 174 locations), and tropical climate (including 155 locations) regions. For these three main climate regions, we analysed the associations between the MFT, the 78th percentile temperature, the annual mean temperature, and the MMT (Fig. 3).
With the projected daily mean temperature under five different global-scale general circulation models (GCMs) and two Representative Concentration Pathways scenarios (RCP4.5 and RCP8.5), we estimate the global distribution of MMTs in the present (2010s) and future (2050s) for each 0.5° × 0.5° grid (Figs. 4 and  5).

This study was a part of a DFG (German Research Foundation) funded project: Ecological and socio-economic functions of tropical lowland rainforest transformation systems (EEFForTs). EEFForTs is an interdisciplinary research project that investigates the effects of land-use change on environmental processes, biodiversity, and human dimensions and is a collaboration between Georg-August University Göttingen and several Indonesian universities. Indonesian management teams were established at the University of Jambi and Agricultural University of Bogor and were responsible for assistance in the procurement of all research and collection permits, as well as permissions from local land owners and managers of the agricultural sites for field sampling. This study was conducted using the research permits 215/SIP/FRP/SM/VI/2012 and 44/EXT/SIP/FRP/SM/V/2013 recommended by the Ministry of Research and Technology of the Republic of Indonesia (RISTEK). As well as, the collection permits 2703/IPH.1/KS.02/XI/2012 and S.13/KKH-2/2013 recommended by the Indonesian Institute of Sciences (LIPI) and issued by the Ministry of Forestry (PHKA). The lowland forest sites were located within protected areas managed by the PHKA and Restoration Ecosystem Indonesia Harapan (PT REKI). Indonesian research collaborators have also been involved in all stages from the conceptualization of the EEFForTs project, field design and sampling, sample exportation for analysis in Germany and finally in interpretation of results. The fieldwork did not involve sampling of endangered or protected species, and was predominantly soil sampling for nutrient element analysis.

This study included three sites in Yunnan Province, China–Banma Mountain in Xishuangbanna, Ailao Mountain in Pu′er, and Yulong Snow Mountain in Lijiang–representing a tropical rainforest, a subtropical evergreen broad-leaved forest, and a subalpine coniferous forest, respectively (Figure 1). These sites are biodiversity hotspots characterized by a high diversity of endemic and rare species and have large elevational gradients (Zhang et al., 2021 (link)). Additional information on the climate and flora of the study sites is shown in Supporting Information 1. We standardized several experimental conditions in each climatic zone, including four equidistant elevational transects, i.e., 800, 1,000, 1,200, and 1,400 m in tropical mountains; 2000, 2,200, 2,400, and 2,600 m in subtropical mountains; and 3,200, 3,400, 3,600, and 3,800 m in subalpine mountains (Figure 1). Five plots (20 m × 20 m) were set on each elevational transect, totaling 60 plots. Furthermore, we standardized the experimental procedures in each plot to determine tree species composition, collect soil microorganisms, evaluate soil physical and chemical properties, and monitor climatic data.

Duttaphrynus melanostictus is a species complex of medium-sized toads (body size in Madagascar, mean ± SD; females = 81.1 ± 11.4 mm; males = 72.5 ± 6.8 mm)¹⁷ native to South and South-East Asia^{24 (link)}, with several invasive populations established in multiple regions of the world^{25 ,26 (link)}. The Asian common toad normally breeds in lentic or slow-moving waters, both temporary and permanent, where females can lay up to 10,000 eggs (FL, unpubl. data). The breeding season is largely dependent on the rainfall regime^{27 (link)}, and in Central Vietnam, where the climatic conditions are similar to the eastern coast of Madagascar^{28 (link)}, takes place in the warmest months with monthly precipitation > 100 mm, and lasts until the beginning of the main rainy season, when the temperatures start to drop^{29 (link)}.
The invasive population in Toamasina was likely introduced via unintentional transport in commercial containers between 2007 and 2011^{30 ,31 (link)}, and the putative point of introduction was identified in the south-west of Toamasina^{31 (link)}.
The invasion is estimated to spread at a rate of approximately 2 km year^{−132 (link)}, expanding in all landward directions and habitats^{9 (link),10 (link)}, which include the urban areas of Toamasina, and the surrounding countryside characterised by croplands, mixed shrubland, and some remnant patches of secondary humid lowland forest^{33 (link)}. This region is characterised by a tropical rainforest climate³⁴ with a drier season (August–November; range average rainfall = 85–124 mm/month) and a wet season (December–July; range average rainfall = 181–343 mm/month), with average monthly temperatures ranging from 21 °C (July) to 27 °C (February)³⁵ . This climate is apparently highly suitable for the D. melanostictus lineage that is spreading in Madagascar^{28 (link)}. Our study period was characterised by a slightly longer drier season than usual, with the first heavy rainfalls in January (Fig. 1).Figure 1

Average daily temperatures and rainfall during the study period (October 2018–May 2019). The grey areas indicate the periods of radio-tracking of the Asian common toad population in Toamasina (Madagascar). Hourly weather data were obtained from the local meteorological station located at Toamasina airport.

We used a free-ranging experimental population of A. femoralis that was introduced in 2012 on a small (~ 5 ha) river island in tropical lowland rainforest located in the Nouragues Nature Reserve, French Guiana (4°02′ N 52°41′ W;^{36 (link)–38 (link)}). The study was conducted between April–May 2022 during the reproductive period of the species^{25 (link)} and all tests were performed during its main calling activity (1400–1900 h,^{39 (link)}). We surveyed the population every day aiming to sample all adult males present on the island and caught frogs using a transparent plastic bag to minimize direct contact and stress. We took dorsal photographs on mm-paper to determine body size (snout urostyle length) using the software Image J 1.52a⁴⁰ , and ventral photographs to identify frogs via their distinct belly patterns. We later confirmed identifications from the field with the pattern matching software Wild-ID^{41 (link)}. In total we caught 76 males with an average body size of 2.9 cm (± 0.1 SD).