Throughout history and before the wide use of wood pulp in paper people have used many different types of materials for writing. This varies from
- parchment / vellum (made from animal skins, including human!)
- bamboo
- plastics
- hemp
- cotton
- flax
- papyrus (made from mashed reeds)
- clay tablets
- slate
People have historically used which ever material filled the need in the required quantity & quality and that was as cheap as possible. For areas with trees, this most frequently was wood pulp. In Egypt, it was papyrus (thank you
Todd Wilcox for helping me round out my answer).
According to Wikipedia,
In papermaking, a dilute suspension of fibres in water is drained
through a screen, so that a mat of randomly interwoven fibres is laid
down. Water is removed from this mat of fibres by pressing and drying
to make paper. Since the invention of the Fourdrinier machine in the
19th century, most paper has been made from wood pulp because of cost.
But other fibre sources such as cotton and textiles are used for
high-quality papers. One common measure of a paper's quality is its
non-wood-pulp content, e.g., 25% cotton, 50% rag, etc. Previously,
paper was made up of rags and hemp as well as other materials.
So apparently in a pinch most any plant fiber will do.
What sort of plant might fill the role of pulped wood depends entirely upon the types of plants in the vicinity of your city. What sort of plants live near your city?
So to answer your supplemental questions:
- Use one of the other plants listed below dependent upon what grew in
their region
- Yes, they would like use one of the other plant fibers.
- Yes, the paper and books made from this paper would likely be more
expensive.
- I don't have any information on a per plant basis but it looks like
it would take more land to produce.
I haven't found any quantitative comparisons between the use of these plants for making writing materials. However, this is what I could find on the qualitative differences:
Papyrus
So far I've found that papyrus was inexpensive to make but the quality of material was significantly less than that of most other materials used to make "paper". Papyrus would crack if folded or bent and it had an uneven surface.
The reeds used to make papyrus only grows in tropical to subtropical climates and they do not tolerate any frost. Since papyrus comes from reeds, it requires a particularly wet habitat.
Hemp Paper
There's another SE site with a comparison between hemp paper and wood paper.
From a strictly production per acre comparison, hemp compares unfavorably (despite its advocate's claims). It would likely cost more to cultivate and require more acres of cultivation to create as much paper. It is apparently more expensive to process.
Hemp seems to have a very wide range of viability from perhaps the equator all the way into Canada in the western Hemisphere - making it perhaps the widest ranging plant considered in my answer.
Cotton Paper
Cotton paper seems to be more economical (less labor and energy) to produce a given amount of paper than hemp fiber, however, it takes more land to produce that fiber and more than four times as much water as hemp. So it's a bit of a mixed bag.
Cotton grows best in warm regions (like Egypt and the Southern US).
Flax Paper
As with the other fibers I've discussed, flax can be used for a wide range of uses from clothing to paper and even bow strings.
Until economical means of pulping wood were developed, flax was one of the primary plant fibers used in the creation of paper. So a civilization without viable wood pulping technology would probably still be using flax as its primary plant fiber in making paper.
I haven't found any production numbers but assume that the amount of fiber harvested would probably compare favorably to that of cotton on a per acre basis and favorably to hemp on a labor/cost basis. In fact, for climates that supported its growth it'd be the most likely replacement for wood pulp.
Flax grows in cooler climes - essentially making it the cooler weather alternative to cotton. However, flax cannot tolerate heavy clay soils.