Study site and sampling
The study was conducted in two locations: Hainan Island and Bnna. Hainan
Island experiences a tropical maritime monsoon climate, characterized by
a rainy season from May to October and a dry season from November to
April. Rubber plantations in Hainan are located at low latitudes and
altitudes, making them tropical island-type plantations. On the other
hand, Bnna has a warm and humid climate throughout the year, with dry
(November to April) and rainy seasons (May to October) similar to
Hainan. The rubber plantations in Bnna are situated at higher latitudes
and altitudes, representing a tropical inland static wind plantation
area type with fertile soil (Lan et al., 2020).
We selected six major plantation sites from Danzhou, Wanning, and Ledong
Districts in Hainan Island, as well as from Jinghong, Menglun, and
Mengpeng Districts in Xishuangbanna (Figure S1). At each site, we chose
three plots separated by distances of 5-15 km for sampling, resulting in
a total of 18 plots. The sample collections were carried out in August
to September 2019 and November to December 2020, corresponding to the
rainy and dry seasons, respectively. Therefore, we obtained 36 soil
samples from each plot, resulting in a total of 216 samples, including
those from the phyllosphere, leaf endosphere, soil, rhizosphere,
rhizoplane, and root endosphere compartments. For each sample, we
analyzed water content (WC), pH, leaf phosphorus (P), potassium (K),
nitrogen (N), and organic matter (LOM). Additionally, we quantified soil
total nitrogen (TN), total phosphorus (TP), total potassium (TK),
organic matter (SOM), available potassium (AK), ammonium nitrogen (AN),
nitrate nitrogen (NN), and available phosphorus (AP). The soil, root,
and leaf sampling approach, as well as the analysis of physicochemical
properties, were conducted based on the methods described in our
previous study (Lan et al., 2023; Wei et al., 2022a). We collected
latitude, longitude, and elevation data for each site. Additionally,
data on average monthly precipitation and average monthly temperature
for each month were obtained from the National Meteorological
Information Center.
(https://www.data.cma.cn).