The Growth and N Retention of Two Annual Desert Plants Varied Under Different Nitrogen Deposition Rates

Abstract

Nitrogen (N) partitioning between plant and soil pools is closely related to biomass accumulation and allocation, and is of great importance for quantifying the biomass dynamics and N fluxes of ecosystems, especially in low N-availability desert ecosystems. However, partitioning can differ among species even when growing in the same habitat. To better understand the variation of plant biomass allocation and N retention within ephemeral and annual species we studied the responses of Malcolmia Africana (an ephemeral) and Salsola affinis (an annual) to N addition, including plant growth, N retention by the plant and soil, and N lost to the environment using 15 N (double-labeled 15 NH 4 15 NO 3 (5.16% abundance) added at 0, 0.8, 1.6, 3.2, and 6.4 g pot -1 , equivalent to 0, 15, 30, 60, and 120 kg N ha -1 ) in a pot experiment. Higher N addition (N120) inhibited plant growth and biomass accumulation of the ephemeral but not the annual. In addition, the aboveground:belowground partitioning of N (the R:S ratio) of the ephemeral decreased with increasing N addition, but that of the annual increased. The N input corresponding to maximum biomass and 15 N retention of the ephemeral was significantly less than that of the annual. The aboveground and belowground retention of N in the ephemeral were significantly less than those of the annual, except at low N rates. The average plant–soil system recovery of added 15 N by the ephemeral was 70%, significantly higher than that of the annual with an average of 50%. Although the whole plant–soil 15 N recovery of this desert ecosystem decreased with increasing N deposition, our results suggested that it may vary with species composition and community change under future climate and elevated N deposition.

The responses to long-term nitrogen addition of soil bacterial, fungal, and archaeal communities in a desert ecosystem

“…The NH 4 + -N and NO 3 − -N accumulation rates may be related to the alkaline soil (pH = 8.74; Table 1 ) in this study, since acidic soils favored the uptake of NO 3 − -N by plants, while alkaline soil favored the uptake of NH 4 + -N ( Marcus-Wyner, 1983 ). The absence of change in TN content in treatments of N addition in this study might be explained by the assimilation of plants ( Cui et al, 2019 ) and the emission of gases such as NH 3 and N 2 O produced by nitrate respiration ( Yue et al, 2019 ).…”

Trait–Abundance Relationships of Annual Ephemerals in Response to Nitrogen Addition in Gurbantunggut Desert

“…Consequently, species with higher leaf nitrogen content usually have a stronger photosynthetic capacity and faster growth rate than others, thus holding an advantageous position in competition and becoming dominant in the community [37][38][39]. As fast-growing and "opportunistic" species, annual ephemerals with high soil seed bank capacity can germinate explosively after snow melting, grow quickly, produce copious seeds, and die within a few weeks in the study area [28,40]. Given the specific life history strategy of annual ephemerals, it would be surprising if leaf N did not affect species abundance.…”

Defoliation and fertilisation differentially moderate root trait effects on soil abiotic and biotic properties

“…This not only results in high nutrient demand of exploitative plants but also more vulnerability and less adaptive capacity to withstand perturbations. For example, faster‐growing, exploitative plants have high nutrient uptake capacities and rapid growth rates, and are typically associated with high rates of soil microbial activity, root exudation, soil organic nutrients mineralisation and nutrients desorption in their rhizosphere (Cui et al., 2019 ; Grigulis et al., 2013 ; Williams & de Vries, 2020 ). In particular, organic compounds such as carboxylate released by exploitative plants have been reported to influence nutrient availability in the rhizosphere (Faucon et al., 2017 ; Wen et al., 2022 ).…”