I have just lent the book to a friend who is a professional in a wildlife job, he knew the story but is really impressed by the book. At a very simple level part of the impact and success is that it is well written. I think also due to the authors personal circumstances she had decide to fully express herself, this is in an academic a powerful expression and a potentially career ending act, as such it brings a personal investment to the book which a reader can feel. To place this work into context it was a work which came at a point of growing awareness of a problem world wide so it did both express an insider knowledge to a wider public and fully inform insiders of their own growing understanding. It in part changed understanding and also fitted the zeitgeist which was just developing. A well written and well argued book which got the timing right. It certainly was not a stand alone work a number of other influential publications were happening in the same time frame.
Derek Ratcliffe in the U.K. was hugely influential, his work on bird of prey egg shell thinning and subsequent decline of populations due to DDT provided the most well known study leading to a change in legalisation in U.K. banning DDT amongst others. Bob Stebbings did similar work on bats and organophosphates. You can find a wide range of workers and publications, I have meet people who saw dead passerines littering fields in 1950s so members of the public were perceiving the issue and receptive to the scientific discoveries.
In Israel birds of prey were lost in huge numbers due to these pesticides in a short period of time, this was well documented and a very clear example. In United States the decline of the peregrine falcon captured public attention as did the work of Tom Cade.
Some of these figures were influential in government, Derek Ratcliffe worked for U.K. government wildlife department and had a massive influence on developing national conservation plans, Silent Spring might have had industry resistance but it also had influential government advisors as supporters.
It is without doubt a hugely influential book, it did not stand alone it represented a much wider and deeper growing scientific awareness of how humans now had the power to alter natural environments in a way never imagined before. If Silent Spring had not been written I do not doubt at all that the legislation and understanding of the impact of DDT and organophosphates would have developed. Birds are visible and have many people who study them, they were very much the miners canary telling people in clear terms that something new and deadly was happening. As birds attract amateurs and organisations such as Audubon and RSPB existed the story would have been told, but perhaps not so elegantly or decisively. Possibly few people have so captured in a book a turning point in human understanding so well, a classic.
The wider environmental movement was already underway it started in the late 1800s with an understanding that trade in plumes was devastating some bird populations. What changed these organisations which could have gone down the path of being strictly animal protection and prevention of cruelty organisations was the growth of knowledge amongst naturalists and early ecologists that changes in the landscape were producing new and varied challenges beyond simple exploitation. A movement which started in response to hunters and egg collectors developed into organisations which first sought to protect land and stop pollution which then discovered it had to manage land.
Charles Waterton established one of the first nature sanctuaries in the 1800s, he also litigated to have a soap works moved which was due to airborne pollution killing trees in his park. The Industrial Revolution in England produced many examples of pollution, common law had a legal response as pollution damaging a personal economic resource had been a long standing problem. It is not a big stretch to take law which protected your riparian rights from pollution by your neighbours dung heap to other sources of pollution. Community responses to common good also had a response in common law, again Waterton attempted to protect wildlife rich common land from enclosure and conversion to arable by enlisting local feeling and interest in people’s rights of exercise and fresh air in this land with shared communal rights. The urban population growing in wealth started to appreciate their rural walks and bird and plant life, Epping Forest and then the New Forest were save by public action in the Victorian era in the USA Muir and others and the creation of national parks mirrored this. More examples exist Hungary started nature conservation activities by I was told by a Hungarian PhD in 1840s.
This understanding of the need to protect habitats, then manage habitats which are too fragmented for natural processes to work in, leading now to rewilding, and also deal with impact of pollution, water abstraction, drainage, coastal processes altered by sea defences, urban sprawl, plantation forestry, agricultural intensification as well as direct exploitation such as rhino poaching or byproduct of industries such as fishing and incidental net deaths. It is a big industry today, part of government and always potentially in conflict with economic interests.
As to public awareness it started longer than we often imagine, some examples are packed cinemas for nature films by figures such as Oliver Pike (1900s) Martin and Osa Johnson (1920)
http://www.bbc.co.uk/bristol/content/articles/2008/02/05/wildlifefilm_feature.shtml
This mass entertainment had a massive impact, the public were receptive as they had a genuine response to nature. One of the topics of early bird photographers (first photo 1892, although a few earlier exist including a storks nest much earlier) was a new phenomena of gulls on the River Thames, this so delighted Londoners that working people would share their bread of their midday meal feeding gulls from bridges, given the widespread poverty of the time sharing their food was a major act and illustrated a deep emotional and aesthetic response.
These early films in U.K. and USA with similar workers in other countries such as Holland had genuine mass public appeal, books and magazine spread this interest. It is based on a deep interest in nature in sections of the public. The Woolhope natural history society had excursions using the new Victorian train system with 500 plus naturalists attending, an unwieldy number for fieldwork and very unlikely to be equalled today.
Nature Conservation in Britain; the formative years John Sheail
Nature Conservation Peter Marren
The Naturalist in Britain David Allen
The new environmental age. Max Nicholson
Ecology and the Industrial Society. T. G. Goodman (1970 very good overview)
A multitude of publications can be found on freshwater biology and impact of lead and copper mines which was a big research topic from the beginnings of ecology in 1920s, not least as specialist lead tolerant plants captured botanists interest, and agricultural orientated scientists such as Stapleton wanted to reclaim derelict mines using heavy metal tolerant grasses, also people’s livestock died due to smelters so a big history of litigation exists.
Adventurers Fen by Ennion
Sand Country Almanac and other American classics are all influential and widely known.
I know this isn't an answer, but, what is The Silent Spring?
Sand Country Almanac, Aldo Leopold, I did mention, I have loved it since I first read it in 1980s, John Muir was arguably a major influence on Roosevelt. I could have added these and more, Walden, it goes on! I am British so a bit of a British perspective but I am quite into North American environmental history I should have added Wildlife in North America by Peter Matthiessen published in 1959, a great read.
https://academic.oup.com/envhis/article/16/3/391/457505
The above review mentions Allen, Grinnel and Hornaday all of whom are well worth reading. North America has such a rich and rewarding nature book tradition which I think has a literary character rarely found in U.K. it is hard to pick out examples Howard Ensign Evans might be unfamiliar to some younger people.