Indigenous vs. Introduced Plants : The Ongoing Debate

Few months ago, I stumbled upon an article written by a representative of an ecological restoration firm that has been promoting native plant species for the past decade. The article sparked controversy by suggesting that non-native tree species need not be shunned altogether. Though the statement was not completely wrong, that article raised eye-brows of many nature-lovers as the statement was contradicting the very soul of that organization. 

So how do you decide what kind of tree to plant? Or perhaps, have you wondered, while walking down a city street or strolling through a park, why did we choose to plant a row of non-native Gulmohor or Rain-trees, instead of trees native to our region? This post aims to provide clarity on this topic by exploring the various factors that influence our tree-planting choices. 

At present, there is a debate on whether to plant indigenous trees or introduced/alien trees. Some favor indigenous native trees while others do not seem to bother about the species. But this debate should be considered from an environmental standpoint.

Different plants thrive in different regions of our country according to the nutrients, climate and habitat. These plants and the wildlife that depend on them create a rich ecosystem, and the introduction of an alien plants into this delicate balance is a matter of ongoing debate. Some say that many introduced shrubs, vines & trees that are naturalised in India, are useful. The examples include guava, custard-apple, grapes, sugarcane etc. But it should be noted here that all these plants are grown agriculturally, where their spread is controlled, carefully maintained. Furthermore, not all introduced plants are non-invasive or benign to the ecosystem.

Proponents of introduced trees argue that they provide shade, oxygen, and visual appeal through their colorful flowers. However, the problem arises when a single introduced tree species outcompetes ten native trees, leading to a tenfold reduction in carbon dioxide absorption and shade. Additionally, habitat loss for birds and pollinators can have devastating impacts on the ecosystem. Introduced species are often free from natural predators & pests, which makes them prone to becoming invasive, out-competing native flora for water and soil. This in turn drives away biodiversity and reduces the chances available for native species, leading to biological pollution. Introduced plants are often short-lived and brittle, making them susceptible to uprooting during storms. The leaves of trees like Eucalyptus and Mangium do not decompose easily and do not contribute to the production of organic fertilizer, resulting in soil pollution. 

While introduced trees like Gulmohar, Copperpod, Jacaranda and Spathodea may look beautiful, their ecological value is negligible. Although a few species of birds may perch on these trees, and pollinators like bees may occasionally be seen on their flowers due to a lack of other flowering species, it would be foolish to conclude that introduced species attract birds and pollinators. Many state governments have banned the cultivation of Eucalyptus due to the large amount of water it absorbs from the soil, which can exacerbate water scarcity issues in certain areas. Introduced species like Gliricidia, Mangium (Acacia Mangium), Earleaf Acacia (Acacia Auriculiformis) and Mesquite (Prosopis Juliflora) were brought to India from Australia and Mexico for rapid reforestation, timber, and fuelwood purposes. However, these same plants have now become a serious threat to ecosystems, competing with indigenous flora and fauna and disrupting nutrient cycling and hydrology. This impacts the overall economic stability of local communities and human health. Many of these species have aggressive root systems or produce a large number of viable seeds, both of which allow the plants to quickly invade the soils outside their growing areas. This resulted in almost destruction of the native Babool (Acacia Nilotica, or recently known as Vachellia Nilotica), which is an important tree species if dry regions. 

Trees native to a particular region have evolved to thrive in specific soil types, rainfall patterns, light availability, seed dispersal mechanisms, and other environmental attributes. In their native environment, these trees may provide cover, food, and habitat for birds, amphibians, insects, and mammals. The tree species that have been living in India for centuries and providing benefits not only to humans but also to wildlife and the ecosystem deserve priority. In fact, there are several fast-growing native trees in India that bear beautiful flowers. Native trees are more adaptable to their growing conditions and more resistant to disease than alien species that have only been introduced in recent decades. You can find the list of native trees here.

Several gardening enthusiasts and nature-lovers derive satisfaction from cultivating rare and uncommon plant species, which are not easily found in their vicinity. In fact, the introduction of new plants is a celebrated activity which delights many gardeners, and attracts media attention. These practices have contributed to scarcity of our own important native species in the urban areas across India. Sadly, it is now increasingly challenging to come across trees like Palash, Sita-Ashok or Kaim in the gardens of many cities. 

In conclusion, it is important to understand the impact of the trees we plant in our region. While non-native species may be visually appealing, they can have negative impacts on the local ecosystem. On the other hand, native trees have evolved to thrive in their environment and provide important benefits to both humans and wildlife. By prioritizing the plantation of native trees, we can promote a healthier and more diverse ecosystem while also supporting the local economy and preserving our cultural heritage. Though there is no need to hate the previously planted and grown non-native trees; at least now onwards, the plantation of any alien or foreign plant must be strongly discouraged. 

Today is 13th anniversary of Gifting Trees... Come, let us all take responsibility to protect our environment and choose the right kind of trees to plant for a sustainable future!

This Summer, Care for Trees?!

Just as we all are troubled by record-breaking temperatures every year, can you even imagine the sufferings of the trees and vegetation in our surroundings? Hot & dry summers can have an impact on your trees, especially when they are young and growing.

Based on NOAA's global analysis, the 10 warmest years on record have all occurred since 2005, and 7 of the 10 have occurred just since 2014. 2020 was the second-warmest year on record based on NOAA’s temperature data, and land areas were record warm.

Similar to the humans who find themselves lethargic and lifeless during these hottest summers, when water is scarce, the saplings you had planted last year also tend to deteriorate. Or when not taken care of in extreme conditions, die. 

At times like these, human intervention is key to helping your trees grow up healthy. Here are a few suggestions or tips which may help in protecting the saplings and young plants you love...

1. Mulch, a fresh layer!

Applying mulch provides some much-needed help for saplings, especially around the root area. Proper application of mulch is a good way to help young trees take in more water and set down strong root systems. Sufficient mulch of about 2 inches thick will not only retain the moisture, but also discourage the growth of weeds. Just do leave some space between the mulch and the base of the sapling.

2. Protect from direct sunlight

A shade net or any cloth for that matter can prevent your young sapling from harsh sunlight in the soaring heat. Shade cloth does not provide complete shade, but improves the diffusion of light and provides ventilation for the plants.

The cloth must be well-supported by 3-4 strong sticks or bamboo so as to act as a windbreak also. The sticks need to be inserted enough into the soil so that they stand strong against the winds. Then a shade cloth can be tied to these sticks in such a way that the plant receives sufficient sunlight, but harsh rays are blocked. Do make sure the plant growth should not be obstructed by the cloth. 

3. Water the plant!

Water the plants early in the morning or late evening when the temperature is not that high. Focus on the root zone to maximize the amount of water they get each time. Knowing how to water your plants properly should be your priority during the summer.

You may try keeping a perforated plastic bottle underground, which you fill every time. This, over a period of time, allows water to seep deeper into the ground, which encourages deeper root growth. 

4. Care of the soil

Soil is a vital part of the natural environment. It’s always better to check the surrounding soil of your plants. When the soil is extremely compact, it prevents the tree from getting the water and nutrients it needs. When the soil is sandy, it can not hold moisture and nutrients. The soil must be a good mix of these both impregnated with mulch so that earthworms can flourish in it. 

5. Watch out for signs of heat stress

Keep a sharp eye out for heat stress on particularly hot days. Common signs include drooping and wilting of the leaves. In case of heat stress, give your tree sufficient water to help it recover. 

A young plant must be taken care of during its first 3-5 years. Then it's just a piece of cake! We are doing the same and shall continue to do that. Today is the 12th anniversary of Gifting Trees... I think we have just begun!

The Black Ebony Tree

Here is the tree which is described in a perfect manner by its name. The generic name is derived from greek word dios which means ‘divine’, and pyros meaning ‘fruit’, referring to the excellent fruit of the genus. The specific name melanoxylon means ‘dark wood’. The Tendu (Diospyros Melanoxylon/टेंभूर्णी, टेमरू, तेंदू) is medium-sized handsome tree, which is also known as Black Ebony. Its small flowers appear from April to June on new shoots.

Tendu, though a minor forest produce (MFP) in Central India, is very underutilized tree. The most economically significant use of this species is that its leaves are used to roll bidis (an indigenous traditional cigarette, which uses the kendu leaf for rolling instead of paper). The leaves possess unrivalled qualities of flavour, colour, flexible and leathery texture, decay resistance and easy workability, which make them admirably suitable for wrapping bidis.

However, most of the harvest goes waste as the fruit has never been explored for its nutritional aspects. This lesser known fruit is edible & is delicious too! Once fully ripen, the yellow pulp is soft & has a pleasant and sweet taste.

Tendu is a seasonal fruit available mainly in summer. The fruit ripening takes almost a year. These edible fruits are largely eaten & disseminated by birds, notably hornbills. The tree produces good seed in alternate years. The fruits and powdered seeds are sold in local markets and eaten. 

The tree is deciduous or evergreen depending on its habitat. In a dry locality, it is leafless for a short time in the hot weather, regaining its leaves in May-June. In a moist locality, it is evergreen. Though the tree has small flowers, the tree is regularly visited by insects and butterflies. It is the larval host plant for the Symphaedra nais & Spindasis vulcanus butterflies.

The tree has been revered in Ayurvedic medicine. The seeds have been prescribed as a cure for mental disorders, nervous breakdowns and palpitations of the heart. The fruits have a cooling and an astringent effect. Dried flowers are reportedly useful in urinary, skin and blood diseases. The bark is astringent; its decoction is used in diarrhoea. Its regeneration is through seeds, cuttings and root suckers. Soaking seeds for about 12 hours in cold water improves germination. Stump planting has been found to be as good as direct seeding. 

Tendu is the most widely distributed and tolerant species when considered to soil requirements. It grows on poor denuded soils, hot and dry hill slopes, stony soils and also heavy clays. It demands light; it is drought and frost hardy but sensitive to water-logging. It is coppiceable & tolerance to pruning makes it a good fodder tree. The tree also pollards well, although the growth of the pollard shoots is slow. Its cultivation on field boundaries or distributed in field crops, such as oilseed and cereal crops, appears to be a feasible and attractive proposition. Its deep tap-rooting habit would minimize competition with annual crops. It gives good quality charcoal. 

The fruit tree being rich in nutritional, medicinal and processing qualities can play a very significant & vital role in the livelihood security of the rural communities through enhanced household income, employment generation and environmental protection. Tendu fruits have a great potential for commercial cultivation. In fact, plantation of Tendu tree along with other local fruits of our region like Ber, should be done in city gardens and residential areas.