Consistent microbial and nutrient resource island patterns during monsoon rain in a Chihuahuan Desert bajada shrubland
Consistent microbial and nutrient resource island patterns during monsoon rain in a Chihuahuan Desert bajada shrubland
复制标题
DOI：
10.1002/ecs2.4475
复制
发表时间：
2023-04
期刊：
影响因子：
2.7
通讯作者：
A. Darrouzet‐Nardi;Isabel Siles Asaff;M. Mauritz;Kathleen Roman;Eleanor Keats;C. Tweedie;Jennie R. McLaren
中科院分区：
文献类型：
--
作者：
A. Darrouzet‐Nardi;Isabel Siles Asaff;M. Mauritz;Kathleen Roman;Eleanor Keats;C. Tweedie;Jennie R. McLaren
在旱地土壤中，表层土壤(0-10 cm)的时空变化对从树冠延伸到地下水的“临界区”的作用起着重要作用。要了解土壤微生物与表层土壤中生物地球化学循环之间的关系，需要对养分、微生物丰度和微生物功能进行重复的多变量测量。我们在奇瓦瓦沙漠巴贾达灌木丛遗址的两个月时间里研究了资源岛和空间中的这些过程。我们收集了Prosopis glandulosa(蜜蜂蜜)、Larrea tridentata(杂酚油灌木)和非植被(间隙)地区的土壤，以测量土壤养分浓度、微生物生物量和潜在的土壤酶活性。我们监测了这些地下过程的动态，因为土壤条件干燥，然后由于降雨而重新湿润。大多数测量变量，包括无机养分、微生物生物量和土壤酶活性，在灌丛和旱期都是较大的，其中中林最大，杂酚油灌丛次之，林隙最小。硝酸盐是一个例外，它的变异性很大，没有显示出资源孤岛的模式。在时间上，降雨脉冲与土壤养分浓度的实质性变化有关，尽管资源岛模式在土壤水分脉冲的所有阶段保持一致。微生物生物量比养分更一致，只有在土壤最干燥时才会下降。潜在的酶活性甚至更加一致，在干旱时期不会下降，这可能有助于刺激在共同定位的涡流塔观测到的降雨事件后二氧化碳外流中观察到的脉冲。这些结果表明，在灌木资源岛(因灌木种类而异)中，有机质循环模式一直处于上升的临界区，高分解势限制了整个景观中土壤有机质的积累，硝酸盐通量与有机质途径脱钩。
In dryland soils, spatiotemporal variation in surface soils (0–10 cm) plays an important role in the function of the “critical zone” that extends from canopy to groundwater. Understanding connections between soil microbes and biogeochemical cycling in surface soils requires repeated multivariate measurements of nutrients, microbial abundance, and microbial function. We examined these processes in resource islands and interspaces over a two‐month period at a Chihuahuan Desert bajada shrubland site. We collected soil inProsopis glandulosa(honey mesquite),Larrea tridentata(creosote bush), and unvegetated (interspace) areas to measure soil nutrient concentrations, microbial biomass, and potential soil enzyme activity. We monitored the dynamics of these belowground processes as soil conditions dried and then rewetted due to rainfall. Most measured variables, including inorganic nutrients, microbial biomass, and soil enzyme activities, were greater under shrubs during both wet and dry periods, with the highest magnitudes under mesquite followed by creosote bush and then interspace. One exception was nitrate, which was highly variable and did not show resource island patterns. Temporally, rainfall pulses were associated with substantial changes in soil nutrient concentrations, though resource island patterns remained consistent during all phases of the soil moisture pulse. Microbial biomass was more consistent than nutrients, decreasing only when soils were driest. Potential enzyme activities were even more consistent and did not decline in dry periods, potentially helping to stimulate observed pulses in CO2efflux following rain events observed at a co‐located eddy flux tower. These results indicate a critical zone with organic matter cycling patterns consistently elevated in shrub resource islands (which varied by shrub species), high decomposition potential that limits soil organic matter accumulation across the landscape, and nitrate fluxes that are decoupled from the organic matter pathways.