Turning to Slide 4. During the second quarter, we generated site rental revenue of $518 million, up 13% from the second quarter of 2011. New tenant additions increased site rental revenue by 6%, reflecting the increased leasing activity driven by the 4 major carriers upgrading their networks. And the remaining 7% growth came from our 2 recent acquisitions. The contribution to site rental revenues from these acquisitions was approximately $6 million higher in the quarter than we had previously expected. Further, we were able to achieve certain cost synergies related to these acquisitions quicker than we had previously anticipated.
Site rental gross margin, defined as site rental revenues less cost of operations, was $386 million, up 15% from the second quarter of 2011. Further, our network services continue to exceed our expectations, reflecting the level of network upgrade activity in the market.
Adjusted EBITDA for the second quarter of 2012 was $379 million, up 18% from the second quarter of 2011.
As shown on Slide 5, AFFO was $215 million, up 19% from the second quarter of 2011. And adjusted funds from operations per share was $0.74, up 17% from the second quarter of 2011. Further, while there were no significant nonrecurring items in the second quarter, I would note that we collected approximately $5 million in cash in the second quarter that we had previously expected to collect in the third quarter, which benefited our AFFO results in the second quarter.Turning to investments and liquidity as shown on Slide 6. During the second quarter, we spent $95 million on capital expenditures. These capital expenditures included $29 million on our land lease purchase program. As of today, we own or control for more than 20 years the land beneath towers, representing approximately 77% of our gross margin. We believe this activity is a core competency of Crown Castle and continue to enjoy significant success with this program as evidenced by the fact that today, 39% of our site rental gross margin is generated from towers on land that we own, up from less than 15% in January of 2007. Further, the average term remaining on our ground leases is approximately 32 years. We continue to focus a significant amount of effort and capital on purchasing land beneath our towers and extending our ground leases.