Jambi province has lost most of its lowland rainforests since selective logging and conversion to other land-uses intensified in the 1970s. The period between 1990 and 2000 was characterised by particularly high rates of deforestation and land-use change (Clough et al. 2016). Today most of the province consists of monoculture plantations. In terms of area covered, rubber and oil palm are the two most important crops in Jambi, with the oil palm area expanding particularly fast.
Our field studies showed that different indicators of naturalness and species richness were highest in the forest, and successively decreased in jungle rubber, rubber plantation and oil palm plantation (Fig. 1C, D). A comprehensive analysis of the biodiversity of different taxonomic and functional groups, including plants, bacteria, fungi, protists, soil and canopy invertebrates as well as vertebrates, documented an overall strong decrease in local diversity in oil palm and rubber plantations as compared to rainforest (Rembold et al. unpubl. data). However, at the plot scale, birds and bats showed no response to land-use change and soil bacteria and archaea (Schneider et al. 2015) as well as certain protist groups (Schulz et al. 2019) had higher diversity in rubber and oil palm plantations than in forest.
Besides strong negative effects on local diversity, land-use intensification also affected the composition of biological communities. For instance, oil palm and rubber forests differed markedly from those of rainforest, while jungle rubber agroforests shared more similarities with forests and were characterised by a relative high proportion of forest species (Prabowo et al. 2016, Rembold et al. 2017, Drescher et al. unpubl. data). Another important trend was the increased abundance and dominance of invasive alien species in the monoculture plantations (Rembold et al. 2017, Drescher et al. unpubl. data).
Important ecological functions including tree biomass, litter decomposition, root health, microbial activity and biomass were significantly reduced in monoculture plantations (Clough et al. 2016, Sahner et al. 2015). Similarly, nutrient-leaching fluxes were higher in oil palm plantations. While the harvested biomass increased from forest to jungle rubber to monoculture plantations, total biomass shows the opposite pattern (Kotowska et al. 2015, Clough et al. 2016). Multidisciplinary research also showed up to 51% reduction in the flux of energy to higher trophic levels of litter food webs in monoculture plantations than in rainforest, indicating strongly reduced predator control of prey species (Barnes et al. 2014). However, the flux of energy into detritivore animal species (i.e. those that feed on dead organic matter) was strongly increased in monoculture plantations, mainly due to earthworms benefitting from higher pH in plantations (Potapov et al. 2019).

Figure 1 Key Fundings
Figure. Multiple aggregate ecosystem functions and their indicators. Yield/harvested biomass (A), carbon stocks (B), naturalness (C), observed local species richness (D), gross margin per hectare (E), and gross margin per hour labor (F). Indicators for naturalness (C) are: proportion forest species among bird communities, proportion indigenous tree species, proportion common weed species present. Indicators for biodiversity/species richness (D) are: number of species/operational taxonomic unit of trees, understory plants, birds, litter invertebrates, termites, ants, testate amoebae, archaea and bacteria recorded per plot. Variables in a-d were standardised to allow joint plotting. Details are given in Clough et al. (2016).