Re: Could you describe to me the food web for the temperate grassland biome?

First, I am a real person, although it is sometimes safer to write using a 
pseudonym, so having satisfied that I'll turn to the food web.

Even the temperate grassland biome doesn't exist as a single type of 
community.  A number of different types of grasslands exist, and a 
complete food web is probably not known for any of them.  Although I 
cannot answer in the specific, I can describe the general characteristics 
of a food web in such grasslands.

The term food refers to eating and being eaten, biological facts of life.  
Autotrophs, literally self-feeders, can capture energy from environmental 
sources and use it to synthesize complex molecules from simple raw 
materials.  The energy that organisms use is stored in the chemical bonds 
of these molecules.  Not all organisms can do this, so all the rest, 
heterotrophs (other feeders) must obtain complex raw materials and energy 
from some other organism, either an autotroph or another heterotroph.  
However, ultimately all the energy available to organisms is the sum total 
captured by the autotrophs.  Many different species compose both 
categories, and the complex patterns of eating and being eaten form a food 
web.

In temperate grasslands, the predominate autotrophs are photosynthetic, 
largely flowering/fruiting plants (Angiosperms)in the Grass family.  
Members of the Bean, Sunflower, and Mint families also make considerable 
contributions with many species among the common plants.  So food webs 
start with green plants.  They use the energy they captured for growing 
and reproducing.  

Heterotrophs consist of two large categories, consumers who eat their 
food, and decomposers who largely grow upon or in their food obtaining 
food by absorption.  Herbivores are primary consumers, those who eat the 
autotrophs.  In grasslands a number of mammals function as herbivores, and 
they usually fall into two categories, small, no bigger than a rabbit or 
prairie dog, and big, like deer, antelope, and bison.  The reason for this 
discontinuous distribution is that plants like grasses are of low 
nutritional value with a lot of bulk, and it takes a big animal to graze 
upon such food.  A lot has to be comsumed and a long, slow GI tract is 
needed to digest it.  Smaller mammals can select among an array of plants, 
selecting those with the highest nutritional value, but since these are a 
smaller and patchier resource, smaller mammals are better adapted for 
using this resource.  Even deer are pretty select eaters on grasslands and 
their browsing is far from random. 

Although the mammals may be the most obvious to another large mammal like 
ourselves, the largest group of herbivores in number, diversity, and total 
mass will be insects.  Some will be specialists on particular plants, 
others will be more generalists.  

In some instances, seed-eating birds and some reptiles can be common 
herbivores too.  

The remaining heterotrophs are seconday consumers, basically carnivorous 
predators who consume the primary consumers, the herbivores.  Birds, 
ranging from small insect eaters to large mammal eaters (hawks, falcons) 
are common grassland predators.  Much rarer are larger predators, usually 
members of the Dog (coyote, wolf, fox), Cat, and Weasel families.  Large 
predators are rare for two reasons.  First, as energy moves from one 
trophic level to the next, from plants to herbivores, not all the energy 
captured is available because some was used for the plant to grow and 
reproduce, and the transfer of energy isn't completely efficient.  As a 
general rule, no more than 10% moves to the next trophic level, so the 
total biomass of herbivores is never more than 10% of the total biomass of 
plants.  Predators would be less than 10% of the consumers, and the 
reduction in habitat size further prohibits their populations.  In terms 
of energy, it takes a pretty big area of grassland to support bison, and 
even more to support large predators like wolves.  So as a general rule, 
big, fierce animals are always rare in comparison to herbivores.

Of course this isn't to suggest there is a straight interaction between 
grass, bison, and wolves.  What makes these feeding interactions a web is 
that they are interconnected.  Several different insects may feed on one 
species of plant, but not on another, which is largely eaten by a 
specialist.  Insects also prey upon other insects, and then you add in the 
insect eaters, and the organisms that may prey upon them, and the 
resulting diagram with lines connecting organisms that eat and get eaten 
in turn begins to resemble a web or net. Lastly of course, all the waste 
products and bodies become energy sources for the decomposers.  

It would take years of study to document all such interactions in any 
particular grassland community.  And even after years of working in such 
communities, we find new interactions all the time.