Land‐use change shifts and magnifies seasonal variations of the decomposer system in lowland tropical landscapes

Abstract

Deforestation and agricultural expansion in the tropics affect local and regional climatic conditions, leading to synergistic negative impacts on land ecosystems. Climatic changes manifest in increased inter‐ and intraseasonal variations and frequency of extreme climatic events (i.e., droughts and floods), which have evident consequences for aboveground biodiversity. However, until today, there have been no studies on how land use affects seasonal variations below ground in tropical ecosystems, which may be more buffered against climatic variation. Here, we analyzed seasonal variations in soil parameters, basal respiration, microbial communities, and abundances of soil invertebrates along with microclimatic conditions in rainforest and monocultures of oil palm and rubber in Sumatra, Indonesia. About 75% (20 out of 26) of the measured litter and soil, microbial, and animal parameters varied with season, with seasonal changes in 50% of the parameters depending on land use. Land use affected seasonal variations in microbial indicators associated with carbon availability and cycling rate. The magnitude of seasonal variations in microbial parameters in the soil of monocultures was almost 40% higher than in the soil of rainforest. Measured parameters were associated with short‐term climatic conditions (3‐day period air humidity) in plantations, but not in rainforest, confirming a reduced soil buffering ability in plantations. Overall, our findings suggest that land use temporally shifts and increases the magnitude of seasonal variations of the belowground ecosystem compartment, with microbial communities responding most strongly. The increased seasonal variations in soil biota in plantations likely translate into more pronounced fluctuations in essential ecosystem functions such as nutrient cycling and carbon sequestration, and these ramifications ultimately may compromise the stability of tropical ecosystems in the long term. As the observed seasonal dynamics is likely to increase with both local and global climate change, these shifts need closer attention for the long‐term sustainable management of plantation systems in the tropics.

Seasonal fluctuations of litter and soil Collembola and their drivers in rainforest and plantation systems

“…This is in line with the results of the study of Cassagne, Gers & Gauquelin (2003) , who reported that litter C/N ratio is an important factor driving Collembola community composition in particular at high soil moisture conditions. Microorganisms sensitively react to changes in microclimate and litter quality ( Fierer, Schimel & Holden, 2003 ; Rousk & Bååth, 2007 ; Zhang et al, 2013 ; Krashevska et al, 2022 ), changing the available food for Collembola. Some Collembola species inhabiting soil were associated with root biomass indicating that living roots may serve as another factor shaping tropical Collembola communities.…”

“…In the tropics, where seasonal climatic variations are less pronounced, seasonal fluctuations in Collembola density and community composition have been reported in few studies, with also usually lower density in the dry than in the wet season ( Palacios-Vargas & Castaño-Menesesm, 2003 ; Wiwatwitaya & Takeda, 2005 ; Muturi et al, 2009 ). Krashevska et al (2022) also reported that soil microfauna, such as Collembola and Mesostigmata are less affected by seasonal variation as compared to soil macrofauna, such as Coleoptera, Psocoptera, and Diptera. However, little is known on changes in seasonal variations in Collembola communities in land-use change context, i.e ., due to the conversion of forest into agricultural plantation systems, particularly in the tropics.…”

“…For example, in temperate grasslands aboveground diversity is promoted by diverse surrounding land-cover, while belowground diversity is positively related to a high permanent forest cover in the surrounding landscape ( Provost et al, 2021 ). Krashevska et al (2022) revealed that land-use change shifts and magnifies seasonal variations of the belowground ecosystem, especially the structure and functioning of microbial communities. Among soil animals, Collembola is a dominant group, abundant and diverse in tropical rainforests and plantation systems ( Hopkin, 1997 ; Devi, Singh & Devi, 2011 ; Susanti et al, 2021 ; Potapov et al, 2021 ).…”

Assessing species richness of the subfamily Campopleginae (Hymenoptera, Ichneumonidae) community in Darab damask rose rain-fed plain, Fars province, Iran

“…5300 hectares (Ebadzadeh et al, 2018). The high quality and commercial value of buds and flowers, rose oil, essential oil, hips, and other by-products encourage farmers to expand the area of rose cultivation by land-use changing, resulting in a negative impact on the unique species-rich natural vegetation type, Juniperus-Amygdalus-Pistacia Shrublands, of this region (Krashevska et al, 2022;Noroozi, 2020). On the other hand, outbreaks or increasing populations of the rose pests and diseases e.g.…”