Pennsylvania Gov. Tom Corbett’s “lean and demanding” 2012-13 state budget proposal has ensured that the commonwealth’s 500 public school districts will again face serious challenges balancing their coming year’s budget.

Corbett’s 2011-12 state spending plan imposed the first serious budget belt-tightening the school systems had to endure in years. Now the districts will have little alternative but to go through a second round of overdue belt-tightening that increasing state subsidy levels in years past did not necessitate.

School districts currently are dealing with the uncertainties contained in the budget plan — stemming in part from changes in the way Corbett wants to fund the schools going forward.

But districts already know that the road ahead isn’t going to be a cakewalk.

While the governor’s school funding plan increases basic subsidies by about $45 million, cuts in other areas of school funding could mean less money overall for some districts.

Whatever hopes the districts still might harbor for more money for the coming year are in the hands of the General Assembly, which will add its input to Corbett’s proposal.

Unfortunately for the schools, it seems unlikely that the Legislature will make any dramatic changes to Corbett’s thinking. Corbett and the state House and Senate sit on the same side of the political fence, unlike the situation that existed when the two Republican-controlled legislative chambers engaged in prolonged budget battles with Democratic Gov. Ed Rendell.

The General Assembly might tweak certain aspects of what Corbett has proposed for education and other budget categories, but lawmakers won’t tear apart the general structure of Corbett’s funding plan, for education or anything else.

The education funding Corbett proposes is in line with his vow of fiscal restraint.

Thus, the school districts also will be forced to impose more cost controls, not only on general budget items, but also in future contract negotiations.

The stage is set for difficult contract talks for districts that will be negotiating with teachers in coming months. The overriding question becomes how flexible, but demanding, districts will be in responding to the governor’s message.

Unfortunately for most school districts, they’re locked into overly generous teacher and administrator contracts inconsistent with the low inflation rate that has existed for years.

On Tuesday, Corbett didn’t ask teachers to accept a pay freeze, like he did last year — which all but a few teacher unions rejected. But the lack of a substantial subsidy increase for 2012-13 will force districts to be tougher in negotiations than they’ve been in the past.

In response to Corbett’s lean school funding proposal, further trimming of teaching and other positions might be necessary in some districts for the year ahead. Unfortunately, some student programs also might suffer cancellation.

Regardless, districts’ struggling taxpayers continue to bear the burden of the Legislature’s irresponsible 2001 pension grab, which increased lawmakers’ pensions by 50 percent and teachers’, by 25 percent — putting a big burden on school budgets and, thus, taxpayers.

So, at a time when many companies and their employees continue to deal with ongoing belt-tightening, the state’s school systems will be getting just their second serious dose of it.

It’s unfortunate that the state must impose such a financial burden on school systems, but the school districts and their employees cannot be spared the economic realities of the times.

What Corbett has proposed is not out of line, and the school districts should — and must — adapt to it.