Plant aboveground biomass data: Tree Competition Garden

This experiment was set up adjacent to E055 in the high disturbance, garden area. 1.75 inches of black soil was added to the CCNHA sandy soil to make four 10 feet x 54 feet plots. The soil was rototilled and aluminum flashing was installed to edge the plots and divide them into 48, 5 feet x 9 feet plots. Equal amounts of MgSO4, CaCO3, P2O5 and K2O are added to the plots each year in early May and late June. For a describtion of fertilizer added, see fertilization details. Seeds were planted with 6 replicates of each of the following treatments:

1. Agropyron repens monoculture
2. Schizachyrium scoparium monoculture
3. Pinus strobus monoculture
4. Quercus ellipsoidalis monoculture
5. Agropyron repens + Quercus ellipsoidalis on half
6. Agropyron repens + Pinus strobus on half
7. Schizachyrium scoparium + Quercus ellipsoidalis on half
8. Schizachyrium scoparium + Pinus strobus on half

The competition plots were split, with half invaded by seed and half to be invaded by seedling. For treatments 5-8, the right or left sides were chosen at random, to plant the tree seeds. The plots were watered throughout the growing season to keep water from becoming a limiting resource.

本实验设置于高干扰性园区内E055号样地附近。将1.75英寸的黑土添加至CCNHA砂质土壤中，构建4块10英尺×54英尺的样地。随后对土壤进行旋耕处理，并安装铝制包边以划分样地边界，最终将整体拆分为48块5英尺×9英尺的次级样地。每年5月初与6月末，向各次级样地施加等量的硫酸镁（MgSO₄）、碳酸钙（CaCO₃）、五氧化二磷（P₂O₅）及氧化钾（K₂O）；关于肥料添加的详细说明，请参阅施肥细则。

本实验针对下述8种处理设置6次重复，开展种子播种实验，具体方案如下：
1. 匍匐冰草（Agropyron repens）单优群落
2. 帚状须芒草（Schizachyrium scoparium）单优群落
3. 北美白松（Pinus strobus）单优群落
4. 椭圆叶栎（Quercus ellipsoidalis）单优群落
5. 半区播种匍匐冰草与椭圆叶栎的混播群落
6. 半区播种匍匐冰草与北美白松的混播群落
7. 半区播种帚状须芒草与椭圆叶栎的混播群落
8. 半区播种帚状须芒草与北美白松的混播群落

竞争样地采用分区设计，一半区域通过种子完成入侵，另一半将通过幼苗实现入侵。针对处理5至8，随机选取样地的左侧或右侧区域播种林木种子。整个生长季均对样地进行灌溉，以避免水分成为实验的限制性资源。