1. Monocultural rubber plantations have replaced tropical forest, causing biodiversity loss. While protecting intact or semi-intact biodiverse forest is paramount, improving biodiversity value within the 11.4 million hectares of existing rubber plantations could offer important conservation benefits, if yields are also maintained. Some farmers practice agroforestry with high-yielding clonal rubber varieties to increase and diversify incomes. Here, we ask whether such rubber agroforestry improves biodiversity value or affects rubber yields relative to monoculture.2. We surveyed birds, fruit-feeding butterflies and reptiles in 25 monocultural and 39 agroforest smallholder rubber plots in Thailand, the world's biggest rubber producer.Management and vegetation structure data were collected from each plot, and landscape composition around plots was quantified. Rubber yield data were collected for a separate set of 34 monocultural and 47 agroforest rubber plots in the same region.3. Reported rubber yields did not differ between agroforests and monocultures, meaning adoption of agroforestry in this context should not increase land demand for natural rubber. Butterfly richness was greater in agroforests, where richness increased with greater natural forest extent in the landscape. Bird and reptile richness were similar between agroforests and monocultures, but bird richness increased with the height of herbaceous vegetation inside rubber plots. Species composition of butterflies differed between agroforests and monocul-tures, and in response to natural forest extent, while bird composition was influenced by herbaceous vegetation height within plots, the density of non-rubber trees within plots (representing agroforestry complexity) and natural forest extent in the landscape. Reptile composition was influenced by canopy cover and openThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

SUMMARYFertilization of rubber plantations has been poorly documented despite the huge economic and ecological impact of this tropical perennial crop, especially in Southeast Asia. The main objective of this paper is to provide information on the fertilization practices of rubber smallholders in Thailand and to investigate the drivers of these practices. Data were sourced from individual interviews conducted with 414 rubber smallholders. The results showed that 99.4% of the mature rubber plantations were fertilized with either chemical or organic fertilizers, or both. The average dose of chemical fertilizers was 105/53/92 kg ha−1 of N/P/K that is consistent with the national recommendations. We estimated that almost two-thirds of the plantations had intensive or very intensive fertilization practices. Geographical location, especially the distinction between historical and new rubber-producing areas, appeared as a major factor explaining differences in fertilization practices. Several drivers commonly found in the literature did not affect the fertilization practices of the rubber farmers, highlighting some specificity of perennial crops and a context where access to fertilizer was not an issue. The high economic and environmental costs of intensive fertilization practices, while their benefit to the yield of rubber plantations continues to be debated, show the need to conduct research on sustainable fertilization practices in rubber smallholdings.

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Description of the subject. With increasing concerns on the sustainability of agricultural systems, many tools have been developed to assess farm sustainability. Objectives. The main objective of this study was to assess and compare the sustainability of different forms of family farm organization. A second objective was to test the relevance of the IDEA method (Indicateurs de Durabilité des Exploitations Agricoles or Farm Sustainability Indicators) to compare tree-crop-based family farms in tropical areas. Method. Percentages of sustainability were calculated based on individual interviews conducted with 25 rubber farmers representing three different types of farm (typology based on the labor used for farming activities), using three scales and 10 components. Results. The socio-territorial scale was the weak point of the rubber farms. In contrast, the economic scale was relatively the best asset on all farms. The factor that most differentiated the three types of farm was the agro-ecological scale followed by the socio-territorial scale. The economic scale did not discriminate. Moreover, only the diversity of production and efficiency components showed a notable difference between the different types of farm. Conclusions. Overall, the three types of farm with contrasting forms of farm organization were not much different in terms of sustainability performance. Family business farms with managerial family labor appeared to be the least sustainable. Thus, as family business farms are becoming more and more important in Thai agriculture, if these results are confirmed on a broader scale, this represents an issue for the sustainability of the Thai rubber sector that would require government intervention.

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