15N tracing experiment 1 Alpinia oxyphylla 1 Amazonia 1 China 1 East Africa 1 Indonesia 1 N-fixing trees 1 West Java 1 agroforestry 1 agroforestry system 1 agroforestry systems 1 ahannon-wiener index 1 alley cropping 1 bees 1 carbon sequestration 1 climate change 1 climate change mitigation 1 cropland 1 cropping system 1 economic benefits 1 ecosystem services 1 farmers’ knowledge 1 forest farming 1 forestland 1 fractionation 1 gross N transformation rates 1 growth form hedgerows 1 home garden 1 improved-fallow 1