Nitrogen uptake and nitrogen use efficiency above and below ground along a topographic gradient of soil nitrogen availability

Bamboo (Phyllostachys pubescens) expansion into adjacent forests is a widespread phenomenon in subtropical regions, and it has greatly changed the dominance hierarchy from trees to bamboos. This process may be accompanied by changes in productivity, nutrients accumulation and biogeochemical cycles. We compared the net primary production (NPP) and major pools and fluxes of nitrogen (N) in bamboo-dominant forest (BDF) and neighboring secondary evergreen broadleaved forest (EBF) in South China using the space-for-time substitution method. We found that the mean NPP of the BDF was 30.0 t ha−1 yr−1, which was 51.5% greater than that of the EBF (19.8 t ha−1 yr−1). The plant N pool for the BDF was 37.5% larger than that of the EBF, whereas the soil inorganic N pool significantly decreased by 31.2% with conversion of the EBF to BDF. Additionally, the ratio of N return to N uptake was 0.69 in the BDF and 0.88 in the EBF because of the lower litter N return of the BDF compared with that of the EBF. These results indicated that the expansion of P. pubescens significantly increased the NPP and plant N accumulation but reduced the soil N available pool and slowed the N cycling rate, which could lead to soil degradation.

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“…The annual NPP, including the aboveground NPP (ANPP) and belowground NPP (BNPP) of vegetation were calculated using the following equations47:…”

Section: Methodsmentioning

confidence: 99%

Accessing the impacts of bamboo expansion on NPP and N cycling in evergreen broadleaved forest in subtropical China

Song

Jun

et al. 2017

Sci Rep

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“…2). Several studies have shown a similar pattern along a topographic gradient (Nakanishi et al 2009;Tateno and Takeda 2010). These findings suggest that leaf N concentration can be determined by soil chemical properties such as soil pH and C/N ratio in the site but vary with micro-topographic relief within the area.…”

Section: Leaf Propertiesmentioning

confidence: 52%

Stem productivity in relation to nitrogen concentration and carbon isotopic composition (δ¹³C) in leaves of hinoki cypress (Chamaecyparis obtusa Endlicher) plantations in Shikoku district, Japan

Inagaki

Miyamoto

Okuda

et al. 2011

Soil Science and Plant Nutrition

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The stem productivity of the hinoki cypress (Chamaecyparis obtusa Endlicher) in relation to plant nitrogen status and water-use efficiency was investigated in the Okuono (OKU) and Karakawa (KRK) areas in Shikoku district, Japan, where abundant precipitation occurs. The nitrogen concentration and carbon isotopic composition ( 13 C) in the leaves were used as indexes of plant nitrogen status and water-use efficiency, respectively. The leaf nitrogen concentration increased with decreasing soil carbon/nitrogen (C/N) ratio and with increasing soil pH. There was a marginally significant negative correlation between leaf 13 C and soil water content in the KRK area, but leaf 13 C in the OKU area did not correlate with the soil water condition, and increased on the upper slope. The results suggest that hinoki trees in the KRK area have higher water-use efficiency (high leaf 13 C) under lower soil water conditions. In the OKU area, meanwhile, leaf 13 C in the upper slope was higher due to adaptation to adverse conditions. When 12 plots in two areas were included, the mean height and stem increments increased with increasing leaf nitrogen concentration and with decreasing leaf 13 C. These findings suggest that nitrogen acquisition is a primary factor for stem productivity in the areas concerned but the productivity of some forests is restricted by the soil water condition or other conditions, as indicated by the high value of leaf 13 C. The measurement of nitrogen concentration and 13 C in leaves can provide us with valuable insights into the relative importance of nitrogen, water and other conditions on stem productivity in the two areas.

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“…In addition to increasing atmospheric CO 2 , the natural level of biologically available N inputs to terrestrial ecosystems has roughly doubled, due to agricultural intensification and expansion and fossil fuel combustion (Matson et al 2002). Numerous studies have reported that increasing N availability can decrease N use efficiency by increasing plant N concentration or reducing photosynthetic carbon assimilation rate (Pastor and Bridgham 1999;Hidaka and Kitayama 2009;Tateno and Takeda 2010). However, most of the studies focused on the leaf-level nutrient use rather than the whole plant level.…”

Section: Introductionmentioning

confidence: 98%

Nitrogen and phosphorus productivities of five subtropical tree species in response to elevated CO2 and N addition

et al. 2015

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The productivities of nitrogen and phosphorus (NP and PP) in plants have been greatly altered by increasing atmospheric carbon dioxide concentrations (CO 2 ) and nitrogen (N) deposition. However, studies on this are quite limited in tropical and subtropical forests. We used open-top chambers to examine the NP and PP of five tree species in response to elevated CO 2 and N addition in subtropical forests from 2005 to 2009. The five tree species included the slow-growing species (Acmena acuminatissima and Syzygium hancei) and the fast-growing ones (Castanopsis hystrix, Ormosia pinnata and Schima superba). Elevated CO 2 increased the NP and PP of C. hystrix. However, the NP and PP of S. hancei were decreased by elevated CO 2 , and the PP of A. acuminatissima was lowered by elevated CO 2 without N addition. N addition had no significant influence on the NP of all tree species, while it increased the PP of S. superba. The changes in the NP and PP were related to those in plant growth. We concluded that C. hystrix and S. superba would benefit from elevated CO 2 and N addition, respectively. The results indicate that plant NP and PP in response to elevated CO 2 and N addition are species specific. Our findings could have important implications for better understanding the effects of global change on species composition in subtropical forests.

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Nitrogen uptake and nitrogen use efficiency above and below ground along a topographic gradient of soil nitrogen availability

Cited by 42 publications

References 59 publications

Accessing the impacts of bamboo expansion on NPP and N cycling in evergreen broadleaved forest in subtropical China

Accessing the impacts of bamboo expansion on NPP and N cycling in evergreen broadleaved forest in subtropical China

Stem productivity in relation to nitrogen concentration and carbon isotopic composition (δ¹³C) in leaves of hinoki cypress (Chamaecyparis obtusa Endlicher) plantations in Shikoku district, Japan

Nitrogen and phosphorus productivities of five subtropical tree species in response to elevated CO2 and N addition

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Nitrogen uptake and nitrogen use efficiency above and below ground along a topographic gradient of soil nitrogen availability

Cited by 42 publications

References 59 publications

Accessing the impacts of bamboo expansion on NPP and N cycling in evergreen broadleaved forest in subtropical China

Accessing the impacts of bamboo expansion on NPP and N cycling in evergreen broadleaved forest in subtropical China

Stem productivity in relation to nitrogen concentration and carbon isotopic composition (δ13C) in leaves of hinoki cypress (Chamaecyparis obtusa Endlicher) plantations in Shikoku district, Japan

Nitrogen and phosphorus productivities of five subtropical tree species in response to elevated CO2 and N addition

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Stem productivity in relation to nitrogen concentration and carbon isotopic composition (δ¹³C) in leaves of hinoki cypress (Chamaecyparis obtusa Endlicher) plantations in Shikoku district, Japan