Vehicle-induced compaction of forest soil affects plant morphological and physiological attributes: A meta-analysis

A main disadvantage of heavy machinery in forest operation is soil compaction. Compacted soils may be a barrier to seedling growth, even though the exact mechanisms of action are not clear yet, especially for different soil textures, plant species and ages. Previous meta-analyses did not find significant effects, mostly due to the limited size of their databases. We analyzed 45 articles for above-ground and below-ground morphological traits and 17 articles for physiological traits, and found significant declines following soil compaction. Declines were higher at below-ground than above-ground traits, in younger (< 2-year-old) than older plants (2 to 20-year-old), in pots than in the field, and increased from the coarse-textured Arenic soils to the finer-textured Loamic or Siltic soils. Data from Clayic soils were insufficient for this analysis. More studies on older plants are also recommended. Responses of conifers and broadleaf species were similar. Our findings suggest that the shorter main roots developed due to soil compaction reduce water uptake and thus photosynthesis and the overall plant physiological performance. No significant changes of nitrogen availability to plants were detected. These results could help a successful seedling regeneration after forest operations.