I have 36 years with a major company, our site is right sizing i was informed tthat my results were sub par and i would be put ona performance improvement plan. Its the first bad review i have ever had, others who lost thier jobs are getting severence as well as pension to leave. I feel i am being forced out, the job is new to me this year and new to site this year. Is this constructed dismissal could i challenge the terms a being forced to leave by hitting my bonus for the first time ever in 24 years as a supervisor

If you do not feel that the performance improvement plan is warranted, then it is important that you address this, in writing, with your employer. If unwarranted concerns continue to arise, this may end up constituting a constructive dismissal of your employment, but as it presently stands, the most important thing that you can do is respond to and defend the allegations against you (to the extent that they are unfair). I'm not sure I understand the last sentence of your question, but if you earned a bonus this year, that could certainly be used as evidence that their performance concerns are invalid. In any event, should your concerns continue or if you are terminated, it is very important that you contact an employment lawyer at the number below. You have accrued significant entitlements over 36 years and you do not want to prejudice yourself in any way.