Alstonia scholaris does not grow naturally in any part of Pakistan as per my knowledge. If any one has ever seen an alstonia tree growing anywhere in Pakistani wilderness naturally than please indicate.Farhan Ahmed wrote:Alstonia Scholaris is an endemic Tree.
It is endemic to Southern and South Eastern India which has a topical / semi tropical climate. In terms of distance, that place is far off from mainland Pakistan and in terms of weather / climate also that place is far different. In Southern India, it rains a lot and there are huge tropical / semi tropical forests. These forests receive huge amount of rainfalls and do not suffer extreme fluctuations in temperatures as we do. Therefore, plants in those areas have a different nature which is not similar to our native plants. That is an entirely different ecosystem.
When we plant a tree like Alstonia in Lahore or Islamabad or Okara or even Karachi, the rains are not that frequent and bulk of them come during two months only. Karachi doesn't get monsoon normally but has less temperature fluctuations as compared to rest of the country. As per its nature, the Alstonia plant wants more water and nutrients so that it can grow a large numbers of soft tissued broad leaves and grow fast. It doesn't get that much of water naturally so it grows long routes to look for more water and nutrients. In the process, it sucks all the nutrients from the soil at that particular spot and other plants find it hard to compete with the giant, ie, Alstonia. The mealy bugs, as pointed out by Khurram sahib, is another menace that come with the Alstonia tree. And when there are hundreds of those trees in an areas, the encourage millions of mealy bugs. And of course those mealy bugs do not stay restricted to Alstonia alone, they go everywhere.
In rainforests, there are animals / birds who prey on mealy bugs and other such insects. We have to understand that there is a complete cycle of interdependent plants, animals, insects, birds, bacteria etc which live in a symbiotic relationship. When you takeout something or introduce something new, it has its consequences which are slow, not easily visible initially but very serious at the later stage.
Farooq sahib has asked that what developed countries are doing with regard to forestation in their countries. Well, forestation in most of the developed countries NOW is strictly native trees. It's a crime to plant foreign species in the wild / outside controlled environment. There are very complicated, long and laborious processes to get the permission for planting foreign tree (of whatever type). It's beyond a normal man's reach to do all that paperwork and go through all those detailed investigations required to induct a foreign plant or animal or bird in native habitat. And if anyone plants at his own than at many places, there are heavy fines and even imprisonment for doing so. The basic logic is that an individual has no right to play with the environmental future of other fellow citizens just because he happens to like a particular tree or animal or bird too much. Plantation outside the controlled environment effect everyone and therefore, strictly not allowed.
As for plantation of Neem Tree in Saudi Arabia, as per my information it was done after due research by the Saudis. They had hired scientists who did the research and recommended this tree. I am not sure if it has any adverse environmental effects so far but none have come to surface yet and neem tree is doing well in Saudi Arabia. In fact, it might be of interest to you that its hard to find neem trees in Pakistani nurseries now. Last year I was looking for around 500 neem trees for plantation at a certain place in Okara. I could not find 500 trees and the reason was that most of the neem plants are exported to Middle East. Of course the guy sitting in middle east was paying many times more than what I could have done. It will be interesting to digout but I think neem trees are being introduced in Middle East after research. And mind you, all of them are being grown in semi-controlled environment. ie, every individual tree has it own water sprinkler so it gets the water that it needs. Important point to note here is that it is being done by Governments after due research and not by individuals. Yet, it is too early to say what impact it will have on their respective environments.