People from all over the world gather nutritional products from trees including fruits, nuts, seeds, leaves, bark and even sap.
Tree products have been an important part of diets for thousands of years, from early humans gathering fruits and nuts (there is evidence of humans eating apples in the Neolithic period) to the first cultivation of important trees, such as mango (Mangifera indica) which has been grown in India for over 4,000 years.
Today, products such as apples, oranges, pistachios and brazil nuts are routinely eaten the world over and form the basis for multi-million dollar industries – the apple industry is estimated to be worth US $10 billion a year, for example.
At the local level, edible tree products are often highly valued by local communities as a core part of their diet, as an important supplement or to sustain them when food is seasonally scarce or when harvests are poor. This role as ‘emergency’ food sources is particularly important and there are several examples of entire communities surviving periods of famine by collecting food from trees.
There are thousands of tree species that provide important food products, but some good examples include:
The Brazil nut tree (Bertholletia excelsa)
This species takes a long time to reach maturity and cannot be grown in plantations. As a result all Brazil nuts are collected from wild populations. One of the most valuable forest products in international trade, the collection of the brazil nut has resulted in the species becoming threatened. It is currently classified as Vulnerable.
Maple trees (Acer sp.)
Trees from this genus produce a sugary sap that, for certain species, is eaten, used for baking or as a flavouring and sweetener. This sap – commonly known as maple syrup – can only be produced in large enough quantities from two species: the sugar maple Acer saccharum and the black maple Acer nigrum.
Holes are bored in the trunk and a single tree can produce up to 100 litres of sap in one season. Canada is the largest producer of maple syrup and in 2008 the value of all maple products sold was estimated to be CAD$212 million. You can read about threatened maple species in the Red List of Maples, published by GTC in 2009.
Baobabs (Adansonia sp.)
Baobabs are found in mainland Africa, Australia and Madagascar. Both Grandidier’s baobab (Adansonia grandidieri) and Adansonia digitata are extremely important food sources. The fruit of both species is rich in vitamins, very nutritious and is eaten raw and made into juice. The seeds can also be turned into oil and the leaves of A. digitata are eaten. Baobab fruit has been called the new ‘superfood’ on the international market after it was approved for use in smoothies by the European Union in 2008.
Apples (Malus sp.)
Apples are one of the world’s most cultivated fruit trees, with over 7,000 different varieties in existence.
Despite their great diversity, most domesticated apples can be traced back to a common ancestor, the wild apple – Malus sieversii. The wild species still exists in China, Kazakhstan, Kyrgyzstan and Tajikistan but is now, alongside a host of other fruit and nut species from Central Asia, threatened due to the loss of its forest habitat.
This species represents an important genetic storehouse of natural variation, which could include disease and pest resistance that may be important in the future.