Tree Physiology FTW!

So I'm trying to find the growth rate for white oak to confirm some stuff, but instead I came across this abstract, which completely goes against the stuff by Bloom about optional nutrient partitioning and marginal technical rate of substitution. In a sense, my mind likens this to the plant having some kind of endocrine problem (although, of course, plants don't have endocrine systems the same way we do-- "hey look, an insulin tree!") I asked Adam, who reminded me that the fundamental components of most enzymes are proteins, and therefore a lack of protein would in turn make a lack of enzymes to allocate carbohydrates to growth processes and instead store them in subsurface storage.

But oh the pain, my WOS does not have access to the article... :(

Optimal partitioning theory revisited: Nonstructural carbohydrates dominate root mass responses to nitrogen

Author(s): Kobe RK (Kobe, Richard K.)¹, Iyer M (Iyer, Meera)¹, Walters MB (Walters, Michael B.)¹

Abstract: Under optimal partitioning theory (OPT), plants preferentially allocate biomass to acquire the resource that Most limits growth. Within this framework, higher root mass under low nutrients is often assumed to reflect an allocation response to build more absorptive surface. However, higher root mass also Could result from increased storage of total nonstructural carbohydrates (TNC) without an increase in non-storage mass or root surface area. To test the relative contributions of TNC and non-storage mass as components of root mass responses to resources, we grew seedlings of seven northern hardwood tree species (black. red, and white oak, Sugar and red maple, American beech, and black cherry) in a factorial light X nitrogen (N) greenhouse experiment. Because root mass is a coarse metric of absorptive surface, We also examined treatment effects on fine-root surface area (FRSA).

Consistent with OPT, total root mass as a proportion of whole-plant mass generally was greater in low vs. high N. However, changes in root mass were influenced by TNC mass in all seven species and were especially strong in the three oak species. In contrast, non-storage mass contributed to increased total root mass under low N in three of the seven species. Root morphology also responded, with higher fine-root surface area (normalized to root mass) under low vs. high N in four species. Although biomass partitioning responses to resources were consistent with OPT, our results challenge file implicit assumption that increases in root mass Under low nutrient levels primarily reflect allocation shifts to build more root surface area. Rather. root responses to low N included increases in: TNC, non-storage mass and fine-root surface area, with increases in TNC being the largest and most consistent of these responses. The greatest TNC accumulation occurred when C was abundant relative to N. Total nonstructural carbohydrates storage could provide seedlings a carbon buffer when respiratory or growth demands are not synchronized with photosynthesis, flexibility in responding to uncertain and fluctuating abiotic and biotic conditions, and increased access to soil resources by providing an energy source for mycorrhizae, decomposers in the rhizosphere, or root uptake of nutrients.