Take a walk outside. Whatever you see, whatever is growing or blocking your view, can be described as the confluence of three factors: geology, climate, disturbance.
The slope and aspect of terrain, the overburdon of surficial material and composition of bedrock determine habitat and influence growing conditions. The bedrock geology of Connecticut records the collision of continents and a central rift valley where dinosaurs roamed. Differences in soil and groundwater chemistry allow calcareous fens to develop in one place, acidic bogs in another.
There is a close correlation between our remaining farm fields and soils considered prime for agriculture. There are geological reasons why the landcover in my town of North Canaan is more than 5% mines.
Climate determines vegetative cover, the presence of ephemeral and perennial water bodies, and the seasonal range of variation in air and water temperatures. It affects the frequency and intensity of weather and the natural disturbance it causes. Terrain influences climate at the local level, as well as prevailing winds and precipitation. Hemlocks grow in cool ravines and on shaded north facing slopes, while acidic ridgetops feature scrubby bear oak and pitch pines.
In my part of Connecticut, the dominant forest cover types transition from central to northern hardwoods, and certain plant and animal species - including red spruce and bog turtles - occur at either the northern or southern extents of their contiguous ranges. Prolonged climate shifts beyond the range of variation will determine the composition and structure of habitats and whether these species expand or contract their populations. This year we lacked the proper freeze /thaw conditions to promote maple sap to run for more than a few days. If this becomes the norm, I will have to put my spiles away and order my syrup from Canada.
Disturbance can be natural or of human origin, and quite often is expressed as the influence of both factors. Wind-throw, beaver impoundments, wild fire, ice storms and herbivory by white-tailed deer impact patterns of natural succession and select for some species over others.
Even natural disturbance can be amplified by human activity - introduced forest pests and pathogens, fire suppression in fire dependent communities and overbrowse by deer expanding into the edge habitat provided by development are just a few examples. Habitat destruction and fragmentation, followed by competition with introduced invasive species, are the dominant factors in the loss of species diversity and ecological disturbance.
The forests of southern New England are second or third growth woodlands, reflecting nearly 400 years of land use history since European settlement. Even the lands we set aside from development grow and support life today in ways that are different from the virgin forests of 1619 (and even these were managed by native American land use practices). We are part of these systems, as much as the rock beneath our feet and the rain that covers the land.