No idea, but what are the common tree species in that part of Russia? Seems to be Ligovo, St Petersburg. There are certainly a lot of birches visible. I believe there are several species in Russia.

I don't know all trees that grew here 100 years ago here but it was pine, birch, willow, oak, etc.

The common tree species now in this place (Ligovo, Saint Petersburg) are: birch, aspen, willow, Populus alba, P. suaveolens.

The most popular trees in Saint Petersburg now are: linden, maple, spruce, pine, willow, mountain ash, larch.

Hardly any way to tell from just those pics other than what floral suggests -- the commonest trees in those locations. The second pic is mostly conifers -- maybe the common spruces that grow there?.

I lived in Russia for over a year, and I remember a lot of Scotts pine. I would think the conifers are those, but I could definitely be wrong. The other memorable tree was betula pendula. Those things are everywhere! In fact, I can kind of see the white bark and the form of betula pendula in a couple of the pictures.

The first picture says "grotto of love on the lake".

Given the very pale trunks, branching structure and blousy tops I would say that the second picture is mostly birch and/or aspen. Apart from the large tree at the right hand end of the bridge which appears to be a conifer. What makes you think the trees would be different now than 100 years ago?

I think the trees would be different now than 100 years ago because this park was destroyed during World War II. Today we also have the park but a lot of trees was destroyed during World War II. It was the front line between the Soviet soldiers and the Germans.The lake was also destroyed too.

I think the trees would be different now than 100 years ago because today we have young forest (young trees).

But maybe I'm wrong, and it's really aspens or birch. Now there are a lot of aspens in the park (young forest with aspens and willows). This is interesting to me, because this was the front line for many years during World War II. Now there are a lot of birch too.

Second photo. Today it's not a forest (I'm sorry for my mistake). Today it's a city. It's a food stand, asphalt, concrete. We have a young small forest but at a distance of 300-400 meters.

Tree species can change drastically. In the Catskill Mountains, not too far away from me, there is an area that was stripped of hemlocks 150-100 years ago for tanning. When the forest grew back, it came back almost entirely as deciduous forest. Hemlock groves are few and far between now. So it can happen.

It might be worthwhile seeing if someone can blow up the photographs to get a better look. You can do that with analog.

Presumably there was a seed bank of deciduous trees in the ground, so they must have grown there in previous stages of the forest and have taken advantage of the new conditions. Cleared areas are colonized by quick growing succession species but that doesn't mean the forest will never regenerate to how it was, if left undisturbed.

I am 99.9% certain that silver birch is heavily represented in those pictures.

I can give more photos from this place.

I see aspen, pine, birch but I am not an expert in identifying trees.

Nor am I. I see the same as you.