NEW YORK, July 23 (Reuters) - Rayonier Inc. (NYSE:RYN - news) -- a supplier of specialty cellulose fibers and holder of 2.3 million acres of timberland -- said on Monday its second-quarter net income rose to $31.4 million, or $1.14 a share, after booking a gain on a timberland sale. The Jacksonville, Florida-based company also cited improved wood products business and lower interest costs behind the net income improvement from $17.4 million, or 63 cents a share, a year ago. This year's second-quarter result included a gain of 75 cents a share from the sale of Pinhook timberland, the company said. Second-quarter sales rose to $346.4 million from $303.9 million. ``The strong dollar and continuing weak global economy make it difficult to predict when market conditions might improve,'' Chairman, president and chief executive Lee Nutter said. ``Third- and fourth-quarter earnings are expected to be lower than the second quarter excluding the Pinhook sale due to weak pricing for commodity absorbent materials and seasonally lower U.S. timber sales volume. However, strong demand for our high value cellulose specialty products is expected to continue.''