Experimental Air Warming of a Stylosanthes capitata, Vogel Dominated Tropical Pasture Affects Soil Respiration and Nitrogen Dynamics.
Experimental Air Warming of a Stylosanthes capitata, Vogel Dominated Tropical Pasture Affects Soil Respiration and Nitrogen Dynamics.
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DOI：
10.3389/fpls.2017.00046
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发表时间：
2017
影响因子：
5.6
通讯作者：
Martinez CA
中科院分区：
文献类型：
--
作者：
Gonzalez-Meler MA;Silva LB;Dias-De-Oliveira E;Flower CE;Martinez CA
全球气候变化导致的变暖预计将在热带地区达到2°C。关于气温对热带农业生态系统，包括觅食牧场的影响的资料少得惊人。在这里，我们研究了2°C的空气温度升高超过环境温度30天的影响，在一个建立的热带牧场（Ribeirão Preto，圣保罗，巴西）占主导地位的豆科植物柱花草Vogel，使用T-FACE（温度自由空气控制增强）系统。在田间条件下，研究了大气变暖对土壤性质（碳、氮及其稳定同位素水平（δ 13 C和δ 15 N），以及土壤呼吸和土壤酶活性）和地上特征（叶片碳、氮、δ 13 C、δ 15 N、叶面积指数和地上生物量）的影响。结果表明，实验空气变暖适度增加土壤呼吸速率相比，环境温度。土壤呼吸与土壤温度和水分在中午（当土壤呼吸最高），但不是在黄昏呈正相关。叶片δ 13 C在对照和高温处理之间没有差异，表明在温暖的地块中生长的植物没有表现出在温暖实验中常见的明显的水分胁迫迹象。在高温下生长的植物叶片的15 N同位素组成低于周围的植物，这表明也许是一个较高的比例的固氮有助于组织N在温暖的植物相比，环境。土壤微生物酶活性下降，响应于空气升温处理，表明在空气温度升高的条件下，有机质的分解速度较慢。土壤酶的能力下降，土壤呼吸和植物生物量的增加，暴露于高温的地块表明，增加根系活动可能导致在这个热带牧场土壤呼吸的增加。这种响应沿着土壤和植物15 N的快速变化，可能与温带草原所显示的不同。
Warming due to global climate change is predicted to reach 2°C in tropical latitudes. There is an alarming paucity of information regarding the effects of air temperature on tropical agroecosystems, including foraging pastures. Here, we investigated the effects of a 2°C increase in air temperature over ambient for 30 days on an established tropical pasture (Ribeirão Preto, São Paulo, Brazil) dominated by the legume Stylosanthes capitata Vogel, using a T-FACE (temperature free-air controlled enhancement) system. We tested the effects of air warming on soil properties [carbon (C), nitrogen (N), and their stable isotopic levels (δ13C and δ15N), as well as soil respiration and soil enzymatic activity] and aboveground characteristics (foliar C, N, δ13C, δ15N, leaf area index, and aboveground biomass) under field conditions. Results show that experimental air warming moderately increased soil respiration rates compared to ambient temperature. Soil respiration was positively correlated with soil temperature and moisture during mid-day (when soil respiration was at its highest) but not at dusk. Foliar δ13C were not different between control and elevated temperature treatments, indicating that plants grown in warmed plots did not show the obvious signs of water stress often seen in warming experiments. The 15N isotopic composition of leaves from plants grown at elevated temperature was lower than in ambient plants, suggesting perhaps a higher proportion of N-fixation contributing to tissue N in warmed plants when compared to ambient ones. Soil microbial enzymatic activity decreased in response to the air warming treatment, suggesting a slower decomposition of organic matter under elevated air temperature conditions. Decreased soil enzyme capacity and increases in soil respiration and plant biomass in plots exposed to high temperature suggest that increased root activity may have caused the increase seen in soil respiration in this tropical pasture. This response along with rapid changes in soil and plant 15N may differ from what has been shown in temperate grasslands.