Data from: A deteriorating state of affairs: how endogenous and exogenous factors determine plant decay rates

Woody plants store large quantities of carbon (C) and nutrients. As plants
senesce and decay, these stores transfer to the soil or other organisms or
are released to the atmosphere. Exogenous factors such as topographic
position and microclimatic and edaphic conditions tied to locations affect
decay rates; however, we know less about how exogenous relative to
endogenous factors such as morphological, anatomical and chemical
construction tied to plant species affect these rates, especially across
different tissue types. We monitored stem, fine branch and leaf decay over
1 year in ‘rot plots’ distributed across four watersheds in ridge top and
valley bottom habitats in a temperate deciduous oak-hickory forest at
Tyson Research Center, MO, USA, in the Ozark Highlands for 21 species of
woody plants that vary in their constructions. We found poor coordination
across tissues in construction and decay, which likely reflects how
functional constraints on living tissues influence recalcitrance to decay.
Additionally, for all three tissues, species membership and construction
were better predictors of decay than was location. Of the construction
traits, chemical composition including total fibre, lignin, cellulose,
hemicellulose and concentrations of multiple microelements were the best
predictors of decay, although the strength of these relationships differed
among tissues. Synthesis. We have long known that rates of biogeochemical
cycling are influenced by exogenous factors, such as climatic and edaphic
factors. Here, we show across plant tissues that endogenous factors,
including species identity and tissue construction, can have stronger
controls on rates of decay within our study system than do exogenous
factors. However, it is likely that the relative strengths of these
different controls change through time and among tissues. We predict that
anatomical and morphological controls may be more important at early
stages and exogenous factors may be more important at later stages of
decay.

木本植物可储存大量碳（C）与营养物质。当植物衰老并腐解时，这些储存的碳与养分将转移至土壤或其他生物体内，或释放至大气中。与生境相关的地形位置、微气候及土壤条件等外源性因子，会对腐解速率产生影响；然而相较于植物物种相关的形态、解剖及化学组成这类内源性因子，我们对外源性因子如何调控腐解速率的认知仍较为匮乏，针对不同组织类型的相关研究尤为不足。本研究于美国密苏里州奥扎克高地泰森研究中心的温带落叶栎-山核桃林内，在山脊顶部与谷底生境的4个流域中布设“腐解样地”，对21种组成特征各异的木本植物的茎、细枝和叶片开展了为期1年的腐解监测。研究发现，不同组织的组成特征与腐解程度之间协调性较差，这或反映了活体组织的功能限制如何影响其抗腐解能力。此外，对于茎、细枝、叶片这三类组织而言，物种属性与组成特征对腐解速率的预测效果优于生境位置。在各类组成特征中，包括总纤维、木质素、纤维素、半纤维素及多种微量元素浓度在内的化学组成是腐解速率的最佳预测因子，不过这些关联的强度因组织类型而异。综合分析：长期以来，学界已知生物地球化学循环速率受气候、土壤等外源性因子的影响。本研究则表明，在本研究样地中，物种属性与组织组成这类内源性因子对腐解速率的调控作用要强于外源性因子。不过，不同调控因子的相对强弱可能随时间及组织类型发生变化。我们推测，解剖与形态调控可能在腐解早期发挥更重要的作用，而外源性因子则在腐解后期占据主导地位。