by Alejandra Parreno
Humans have been modifying nature for centuries. As a result,
beautiful places that we might consider “natural”, are actually the result of
human interventions. Obvious examples of man-made landscapes can be a farm, a
city or gardens. But sometimes it is hard to realize when something is natural
or artificial: for example, when a forest is native, grown for forestry or part
of a restoration program. Of course
there are different levels of intervention, from landscapes that have been
completely designed and managed to those where only side effects of
civilization have reached, usually called semi-natural. In fact, it is
considered that no landscape has been left in its natural state, but all have
different degrees of “naturalness”, which is the way we perceive landscapes as
being natural or man-made. Ecological naturalness, refers to the ecological
aspects of our interventions in nature.
There is nothing inherently wrong with artificial landscapes; they provide humans with a home, food, recreation, and everything we need to survive. However, as a landscape becomes more artificial, usually the least it can preserve the biotic interactions, or keep resources clean in the long term. Therefore, it is certainly good to be able to identify them and not forget the goods that natural landscapes also represent for human wellbeing, biodiversity and ecosystem functions in general. Whenever possible, we should try to reduce our long-term impact in both, so as to allow for adaptation and preserve resources. Aborigine tribes in the past usually strived in achieving this, as they developed at the pace of natural processes, without major impacts in the environment.
So how to identify human footprints in the landscape? For instance, we humans tend to create geometric structures: squared gardens with uniform edges and symmetrically placed flowers, straight rivers without meanders or slopes, and uniform forests with little diversity of species. In order to build our farms and cities, we usually shift the course of rivers, the shape of lakes, the limits with the ocean (usually by filling wetlands with soil), we cut long grasses to keep them tidy and we bring water to deserted or cold areas to make them more productive. All the elements that we use for these activities denote a landscape that has been adapted to human needs. Lately, there are trends to preserve natural landscapes that represent the opposite to this traditional management but still constitute an intervention, for example green roofs in cities or letting native weeds grow in the borders of farms to protect local flora and fauna.
Preserving landscapes as close to native as possible is tricky, as we flood the world with foreign elements (like plastic) and we modify large scale processes (like climate or nutrient flow). However, we can still appreciate close to natural landscapes in national parks, reserves and not-habited places. Biodiversity is usually a reliable element of natural landscapes, although attention has to be paid to whether species are native or introduced and this requires a bit of historical knowledge on local ecosystems. Monitoring biodiversity in landscapes as an indicator of human impact is really important. Other hints of “naturalness” can be found in water, air and soil quality and in the periodicity of earth and climate processes, like volcano eruptions, floods from rivers rises, presence of all levels of food webs (from autotroph plants to top predators) and absence of non-biodegradable elements (like concrete or plastic). Eventually, when humans leave an area, nature takes back the wheel and drives ecosystems to a new state that in the distance future we could probably consider as “natural” again.