Wherever on the world, if there is some kind of animal life on land, one can be sure there are spiders; spiders belong to the most occurring animals. Differences of climate don't make up any problem for this animal group; their only life condition is the presence of prey.
The differentiation of climates, micro-climates and environments results in a enorm diversity of spiders species. The ciphers talk for themselves: at this moment we know more than 27.250 different species, divided amongst 50 families. According to some estimates the total number of species could be around the 50.000, which means this is a beautiful occassion for the spider-lovers to make discoveries and add these to the treasure-chest of the fauna!!!
Apart from climate and environment, micro-climate and micro-environment are of great importance of the presence of spiders! Every small environment as a woodland, a dune, a heath &tc.., can be divided in a number of stories. Every story has his own species.
On base of this, one can make a stratigraphical classification: spiders that live IN the ground, spiders that live ON the ground, spiders that live ON and BETWEEN low overgrowth (e.g. moss), spiders that live on low bushes, spiders that live on high bushes and spiders that occur on VERTICAL surfaces as tree-trunks, walls &tc.
With these classifications we assume the fact that spiders are land animals; however, there is one exception: the water-spider that is found everywhere in Europe and Asia in clear, clean, not-moving water.
Some spiders can be found very easily; orb web spiders catch the eye, but other species are only detected after a goal-oriented search, especially those who live a more or less hidden life, as for instance the the purse-web spider (Atypus).
In principle the same method is followed by the ecological study of spiders and spider communities as the one which is used by the study of plant communities. On a outlined square meter the occuring species and the quantities per species are registrated. Plants do not move, spiders do: so pay attention by the count and do not forget to check up the different "layers". Besides the data of the catch, the data of the environment have to be noted down: plant species, the density of the overgrowth, the substratum (micro), the climatological conditions &tc.. Before taking test samples, establish globally if these are assumed to be representative!
The environment does not only offers the spiders food and protection, it contains also dangers. Spiders have, as all other animals, enemies. Defence and flight are the first arms to strike back or to avoid an attacker. For their defence the spiders use their poisoned fangs; but before they use this weapon they 'll take a threat pose. This pose has the purpose to deter or to avoid the attacker and to make the spider appearing bigger than she is. If the threat is to big according the spider, or an unknown danger threats, the spider flies as fast as a lightning bolt. Hunting spiders just run away, web spiders use a spun thread to drop slowly out of their web or hiding place, or just drop themselves. If the danger came unsuspected, the nature has endowed the spider a passive defence method: camouflage. For many animals - spiders included - the theorem "take care of being inconspicuous, that is the key to your surviving chances" counts.
Besides camouflage through colour adaption, there is another way to be inconspicuous: camouflage through shape adaption or mimicry i.e. the phenomenom that some animals in appearance (not in build) resemble other animals or parts of plantswhereby they are very difficult to detect. There are for instance in the group of the sac-spiders many species that resemble outwardly on ants.
One has assumed that the greatest enemies of the spider are the spiders themselves. If this is true, the human being comes second! Uncountable numbers of spiders are "cleaned up"(due to ignorance?) by men as a result of the use of pesticides in agriculture and horticulture, hitting as well the spiders and their prey. Then we have the birds, the lizards, the toads and frogs that are not averse from spiders. Some insect-species as ichneumon flies, black-banded spider wasps and digging wasps are great threats for a peacefull spider-existence.
The Belgian and Dutch digger wasps hunting on spiders bear the well choosen name "Spiderkillers" and are to be found mainly on heaths.
If you want to know more about the ecology of the spiders, I suggest strongly you read"Spiders in ecological webs"of Dr.WISE D.H. - 1993, Cambridge University Press - ISBN 0-521-32547 as well as the books"Introduction to experimental Ecology" van Lewis en Tylor, Academic Press 1967 and "Spiders, Webs, Behavior and Evolution" from Dr. Shear, Stanford University Press 1986.