Sustainability is a topic central to thinking and debate on the future of the planet. The Botanical Garden of Padua contributes actively through targeted initiatives and complex strategies, in an effort to imbue a mere word with meaning and turn it into concrete actions that can make a difference.
Projects cover various sectors and areas of activity, such as responsible water management — matching consumption to the effective needs of the plants, and consequently eliminating waste — and the use of electric machines, with the introduction of the first bio-shredder in 2014, and subsequently the replacement of petrol brushcutters and blowers. Thanks to the bio-shredder, in particular, all organic matter produced in the Botanical Garden can be reduced mechanically to compost and used as fertilizer: part of the shredded material is sterilized and used to prepare substrates for plants grown in pots, the remainder is spread around green spaces, on lawns and flower beds, and in the arboretum.

There are other initiatives and measures too, adopted over time and having positive effects in terms of sustainability; among these are the policy of mowing less frequently, so that more species can grow to different heights, and a reduced reliance on insecticides, especially those which are damaging to plants. For years now, it is larvicides (not adulticides) that have been used to control mosquitoes: beneficial above all from the standpoint of prevention, they ensure that pollinators such as bees and bumblebees are not attacked or killed indiscriminately. Insects like these must be protected, as they are invaluable for biodiversity. What is more, plants are monitored continuously so that infestations can be detected early on, and integrated biological control strategies are activated through the introduction of antagonistic insects into greenhouses, where they are able to attack harmful organisms. Likewise in the general area of pest control strategies, use is made of aids such as sticky strip type products, coloured yellow or blue, which lure insects visually, and others that function by means of food or sexual attractants.

Another element in this complex and far-sighted approach — one of developing and achieving real sustainability goals seen as long-term commitments — is the Solar active building that houses the new greenhouses of the Biodiversity Garden, a structure designed to have as low an impact as possible on the environment. 100 metres long and 18 metres high, the greenhouse building is designed to enable maximum exploitation of the sun’s natural energy. Rainwater is harvested in a basin holding 450 cubic metres, and it is a curtain of this same water, marking the entrance to the Biodiversity Garden, that ensures the supply held in storage is circulated and oxygenated. An artesian well 284 metres deep draws water at a constant temperature of 24 °C, allowing tropical aquatic plants to thrive all year round and supplementing the harvested rainwater supply in times of drought.

Electrical power produced by solar panels is used to run the pumps controlling the water cycle, and contributes to the operation of the building systems. Opaque interior and exterior surfaces are coated with a photocatalytic compound designed to produce a chemical reaction induced by ultraviolet light, the effect of which is to bring about a considerable reduction in air pollution. It is estimated that 150 cubic metres per square metre can be cleaned of pollutants daily.

In addition, a new technique for growing shrub-like plants has been adopted, and is in use on non-transparent roof areas of the building shell. This greening of spare structural space has a positive impact on the environment, as the building consumes less energy, the plants produce oxygen, and levels of carbon dioxide and particulates in the atmosphere are also reduced. The greenhouse effect is exploited to save energy and keep each section within the temperature and humidity parameters of the replicated climate zone. Heat produced by solar radiation is trapped inside the greenhouses: in wintertime, warmth accumulates during the day in the masonry, and is released at night; in summer, excessive heat is avoided by opening the windows and movable parts of the roof. The input signal that controls the opening and closing of the windows is provided by the actual plants, which respond to changes in temperature and humidity by giving off detectable levels of carbon dioxide and oxygen. A computerized system correlates the data provided by the plants with the optimum plant survival parameters for each climate zone. The material employed for transparent areas of the greenhouse roof is pneumatic Ethylene Tetrafluoroethylene (ETFE), a corrosion-resistant plastic advantageously lighter and more receptive than glass to the ultraviolet radiation needed by plants: the aerated membrane captures the sun’s heat by creating an air cushion, which reduces losses through radiation at night.