End-of-study internship carried out by Marie-Amélie RICHEZ

ISTOM – School of international agro-development
April – August 2024
Supervisors: Catherine Sabinot (IRD), Maya Leclercq (IRD)

She defended her final thesis on October 17, 2024 in front of the ISTOM jury team, students from the same school as well as her supervisors. Marie-Amélie also participated in the animation of 2 restitutions to the stakeholders (farmers and institutional actors) of the CLIPSSA project in Tahiti.

Memory summary

In a context of climate change, the Pacific islands, which include French Polynesia, are facing sometimes extreme atmospheric phenomena impacting various sectors, including agriculture. The CLIPSSA project, into which this dissertation is integrated, focuses on the one hand on the production of new scientific data on the future climate of the South Pacific, and on the other hand on the analysis of sectoral impacts, in order to support strategies adaptation to climate change carried out by public authorities.

The thesis focuses on the resources mobilized by farmers on the Taravao plateau in order to learn and/or transmit their agricultural knowledge and know-how in a context of climate change. The results show that there is a diversity of material and intangible resources mobilized by farmers.

The mobilization of these resources results in various learnings which, in certain cases, allow farmers to find solutions adapted to their constraints, including the impacts of extreme weather phenomena affecting the Taravao plateau. This “local knowledge” is essential resources on which to support current and future climate change adaptation strategies.

Context of the study

French Polynesia, located in the heart of the Pacific Ocean, faces significant socio-economic and environmental challenges, particularly in the tertiary sector. Its economy is partly dependent on financial transfers from the French state, and the agricultural sector, although modest in terms of its contribution to GDP, plays a crucial role for the territory’s food security. The cultivated area is small, only 9% of the land surface is cultivated, or around 40,000 ha of usable agricultural area (UAA) (Dubreu et al., 2024).

In addition to the low proportion of cultivable land, the decline of the agricultural workforce, as well as land complexity, particularly linked to the joint ownership of land and access to land, pose obstacles to the expansion of agriculture. local agriculture. In addition to the aforementioned socio-economic constraints, there are environmental constraints, including the impacts of climate change which weigh on agriculture.
In Taravao, a commune in Tahiti, farmers produce a diversity of vegetables, tubers and flowers.

Although market gardening is the majority, the study presented also focuses on the production of vanilla and taro, a tropical tuber, respectively for the sensitivity of vanilla flowers and the resistance of taro to certain phenomena punctuating or governing the daily newspaper on the island. To ensure the productivity of their fields, farmers implement practices, adapt and readjust them over time, constraints encountered, etc. This adaptation is fueled by a process of learning and transmission of local knowledge and know-how in which we are interested.

Main results

The meetings and exchanges with 22 farmers organized over two and a half months in the field allowed the collection of information regarding the learning resources and transmission of local agricultural knowledge and know-how that they mobilize. There are intangible and material resources.

– Intangible resources are vectors of information and therefore of knowledge and know-how. It is through these resources that the circulation of one or more information takes place. This includes the human network (family, professional and friendly), Information and Communication Technologies (ICT) and other information media (magazines, thesis, etc.), specialized groups such as associations, etc. and diploma courses. Finally, empiricism, or practical experience, appears to be an essential resource for learning knowledge and know-how.

– Material resources are physical resources which allow the implementation of a change in practice as they make the application of a solution possible (e.g. the tractor and its accessories for mechanized tillage, system irrigation for water supply to crops, etc.). There are various inputs which depend on the activity carried out, such as agricultural equipment (e.g. greenhouses, tractors, irrigation systems, etc.), chemical and natural inputs, i.e. fertilizers, pesticides, herbicides. , etc. and finally the water resource.

The daily or occasional mobilization of these resources contributes to the implementation of new agricultural practices by the farmers met on the Taravao plateau. Among the practices put in place, several aim to partially overcome meteorological constraints. Indeed, the farmers we met say they have to deal with the impact of heavy rains, periods of low rainfall accompanied by intense heat felt or even the shift in seasons with a later arrival of the cool season.

What practices are put in place to overcome these constraints?

Example of greenhouses to minimize the impacts of heavy rain

Rain is among the atmospheric phenomena impacting crops most cited by farmers. These cause significant impacts, particularly on market gardening and vanilla crops due to their intensity or duration. In the market gardening sector, a prolonged rainy episode can sometimes partially or totally compromise harvests, depending on the sensitivity of the crops to excess water. The rains also represent a threat to the production of vanilla pods due to the fragility of their flowers. Under the influence of rain, the pollen melts and manual pollination of the flowers becomes impossible. Without pollination no vanilla pod will be produced. During the rains, as many pods are lost as unpollinated flowers. Finally, through the speeches of farmers, taro does not appear as a production particularly sensitive to rain in comparison with market garden vegetables and vanilla; although the sensitivity of taros to humidity differs depending on the variety.

The farmers and vanilla growers met in Taravao are implementing various adaptation solutions, including the installation of greenhouses. Greenhouses help protect crops from the direct impact of rain by providing a waterproof cover. By freeing themselves from the rain constraint, it is possible for market gardeners to extend the production period of certain crops, notably tomatoes, the cultivation of which is extended over the hot season, a rainy season (southern summer of November to April).

This then ensures financial income over this period: “Taravao is renowned for being a very rainfed area. It’s raining a lot, a lot. As a result, in the rainy season, we cannot grow vegetables because it rains too much. All those who are in open fields like that, when they have rain, they have more vegetables. So, we installed greenhouses to be able to fill this gap. And here we are, in the rainy season, we can still produce.” (Market gardener, 30-35 years old). Please note, however, that installing a greenhouse represents an investment that not everyone is able to cover. The financial capital available to the farmer in question can therefore act as a limiting condition for the implementation of such a solution.

Conclusion

In addition to the example presented above, the study carried out in Taravo made it possible to highlight resources that are a priori commonly mobilized such as the family or, for a minority of farmers, specialized groups. These resources sometimes allow the modification of agricultural practices to overcome various constraints.

For example, economic constraints push certain taro producers to abandon the cultivation practices of their ancestors (mobilization of the lunar calendar, use of mechanical tools) in favor of less energy-intensive and time-consuming methods, thus allowing the profitability of cultivation. . Economic constraints are not the only thing weighing on agriculture. Indeed, although extreme atmospheric phenomena are not at the heart of farmers’ discussions and concerns, their impacts are real and observed.

It is clear that farmers are implementing various strategies and tactics to compensate, or at least mitigate, certain impacts of extreme atmospheric phenomena. The adoption of new practices is, however, conditioned by various factors including the economic factor which slows down possible material investments. Finally, let us note that this is indeed all the practices of farmers which make it possible to mitigate the effects of atmospheric phenomena.

Analyzing the modalities of adaptation of these practices within the framework of this dissertation makes it possible to nourish the CLIPSSA project, which aims, in the following stages, to co-construct with local public policies strategies to support adaptation to the climate change, based both on current climate simulations and local knowledge.