34% of enterprises report 'reducing headcount' in Q4? Why is this?

I'm certain that the actual reasons are vast and varied from sector to sector and company to company. However, I can offer a few reasons I've seen from my own direct and indirect experiences.

I believe one big driver to be the uncertain cost of human capital within the enterprise. With healthcare regulation and reform still up in the air, employers are in a precarious position. The looming threat of healthcare costs increasing at an even higher rate than we've already been experiencing is a risk that can severely hurt margins in the long term. Rather than wait and see how things shake out, it is safer to make the cuts now and look at outsourcing or selective re-hiring if the need for more people should arise.
Another reason is that everybody's doing it! Generally, layoffs can be an indication of weakness or danger within an enterprise. However, when everyone is doing it at the tail end or just after a severe recession, the stigma is diminished. This was an opportunity for even relatively healthy enterprises to trim a little off the waistline without raising eyebrows or impacting investor confidence.

Finally, a note on the huge discrepancy between enterprise layoffs versus small businesses. Personnel cuts generally have a very negative impact on employee morale and subsequently on productivity. Within the enterprise environment, cuts tend to be less personal and the overall impact is somewhat lessened. However, in a small business environment, the management structure is generally much flatter. Individual contributors often (or even typically) know their CEO on a first-name basis. This makes reduction in headcount very painful and it will generally only be used as an absolute last resort.

Further, small businesses are generally leaner to begin with. If there were a Body Mass Index (BMI) for businesses, we'd likely find most enterprises to be obese and small businesses athletic and healthy. Extending this same analogy one step further, when small businesses make cuts, they are generally trimming muscle as opposed to fat. When they make cuts, they are directly impacting their production capabilities. The remaining people have to work much harder to make up the difference whereas the enterprise workforce may notice little to no measurable increase in individual workload.

I believe these and other factors like the typical inverse relationship between inflation and unemployment, availability of credit, weak demand for consumer and retail goods and a myriad of others made for a perfect storm of sorts. However, I remain confident that the late season pruning we experienced last year will lead to excellent sustainable growth going forward.