If wild life vanishes, man cannot be really far behind from vanishing. Man also will vanish from the Earth after some thousands of years.
Wild life means all the animals, insects, birds, microbes etc in the forests other than plants. Change in wild life will affect the ecosystem over thousands of years. The flow of energy, matter and food will be affected. The food chain (food web ) will be affected.
If there are no consumers of plantation in the wild then the vegetation will be affected. The recycling of nutrients will be affected if decomposers of dead organic matter are not there. If vegetation is affected, then ecosystem will be unbalanced. Climate will change a lot. If the climate changes too much then human beings will not be able to live normally.
They need to construct closed and protected buildings and live inside only. Such arrangements cost very high and need a lot of energy. The resources on Earth will be consumed faster. When man cannot extract more resources from earth and utilizes too much of the available energy, then he has little to survive with. The human beings will evolve into some new shape and attributes during this process.