Shifts in root dynamics along a hillslope in a mixed, mesic temperate forest,Plant and Soil

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Shifts in root dynamics along a hillslope in a mixed, mesic temperate forest
Plant and Soil ( IF 3.9 ) Pub Date : 2022-05-05 , DOI: 10.1007/s11104-022-05469-3
Edward J. Primka IV _{1,

2,

3} , Alexandra S. Buck ₁ , David M. Eissenstat _{1,

2} , Thomas S. Adams ₄

Affiliation

Aims

Complex topography, a common feature of forested areas, generates unique environmental gradients that may shape root dynamics in unexpected ways. Nevertheless, belowground studies rarely capture the environmental gradients imposed by complex topography, such as those found along hillslopes. This begs the question: how much information is lost when complex topography is ignored? Hillslope is a common aspect of complex topography with landscape features that impact water flow, sediment transfer, and water and nutrient storage. We hypothesized that soil water content would have a nonlinear impact on fine-root production, mortality, standing crop, and turnover. Specifically, we expected increased mortality and decreased production, root standing crop, and turnover at the driest and wettest regions of the hillslope.

Methods

Using minirhizotron observations from 150 tubes located at 50 sites strategically placed at different hillslope positions across a first-order catchment, we examined how position along a hillslope impacts fine root dynamics.

Results

Contrary to our hypotheses, we found no significant hillslope effects on fine root tip production or mortality. Root tip turnover, however, was higher at drier than wetter regions of the hillslope. Additionally, fine root standing crop length was higher in wetter topographic regions.

Conclusions

Considering fine root tip turnover and length standing crop in combination with previous research on fine root lifespan suggest two distinct strategies of trees in root deployment along a hillslope: temporal avoidance in drier regions of a landscape (midslope planar and ridgetops) and extended survival of roots in wetter, deeper-soil regions like valley floor and swales.

中文翻译：

混合温带森林中沿山坡的根系动态变化

目标

复杂的地形是森林地区的一个共同特征，它产生独特的环境梯度，可能以意想不到的方式塑造根系动态。然而，地下研究很少捕捉到复杂地形所施加的环境梯度，例如沿着山坡发现的环境梯度。这就引出了一个问题：如果忽略复杂的地形，会丢失多少信息？山坡是复杂地形的一个常见方面，具有影响水流、沉积物转移以及水和养分储存的景观特征。我们假设土壤含水量会对细根生产、死亡率、成活作物和周转产生非线性影响。具体来说，我们预计山坡最干燥和最潮湿地区的死亡率会增加，产量、根系作物和周转率会下降。