Impact of elevated nitrogen inputs on seedling growth of five dry tropical tree species as affected by life-history traits

Khurana, Ekta; Singh, J. S.

doi:10.1139/b03-132

Cited by 14 publications

(25 citation statements)

References 31 publications

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“…, Giardina et al. ), and two with potted seedlings (Lawrence , Khurana and Singh ). They also include a six‐week study concerning the timing of production, not the level of production (Nomura and Kikuzawa ).…”

Section: Discussionmentioning

confidence: 99%

Plant responses to nutrient addition experiments conducted in tropical forests

Wright

2019

Ecological Monographs

107

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I present a meta‐analysis of plant responses to 48 nutrient addition experiments conducted with native species in naturally growing tropical forests, exclusive of mangrove forests. The added nutrients include nitrogen (N) in 36 experiments, phosphorus (P) in 33 experiments, calcium and potassium in one experiment each, and various mixtures of essential nutrients in the remaining experiments. I evaluate the hypotheses that nutrients limit tropical forest plants, nutrient limitation is stronger in successional than in old‐growth forests, P but not N is limiting in lowland forests, and N is limiting in montane forests. Responses to the most complete nutrient mix used in each experiment were strong for plant functions that contribute to aboveground production (Hedges’ g averages 0.87) and nonsignificant for fine root biomass. Responses to N addition and to P addition were strong for tissue concentrations of the added element (Hedges’ g averages 0.75 and 1.4, respectively), moderate for fine litter production (0.64 and 0.65, respectively), moderate to weak for plant growth (0.46 and 0.37, respectively) and nonsignificant for fine root biomass. Growth responses were stronger in successional than in old‐growth forests. All responses were unrelated to elevation. The 48 experiments included 30 factorial nitrogen‐phosphorus experiments that enable additional direct tests of the widely cited hypotheses that P limitation is stronger than N limitation in lowland forests and vice versa in montane forests. Both hypotheses were rejected. The N × P interaction effect was nonsignificant across the factorial experiments. In conclusion, nutrients clearly limit tropical forest plants. Limitation by N is widespread in both lowland and montane forests, and the same is true for P. Single experiments identify limitation by calcium and potassium, and correlative studies suggest limitation by calcium, potassium, and magnesium. The available evidence is consistent with the possibility that most macronutrients limit tropical forest plants; however, experiments focus almost exclusively on N and P. The way forward will include taking fuller advantage of existing nutrient addition experiments, siting new experiments strategically, and developing cost‐effective methods to assay responses to all of the essential nutrients soils supply to plants.

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Section: Discussionmentioning

confidence: 99%

Plant responses to nutrient addition experiments conducted in tropical forests

Wright

2019

Ecological Monographs

107

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“…In general, higher N availability enhances biomass and relative growth rates and decreases root: shoot ratios (Huante et al, 1995a;Mendieta-Araica et al, 2013). The response to elevated nutrient availability is higher in light-demanding species compared to shade-tolerants (Huante et al, 1995a), in smallseeded species compared to those with larger seeds (Huante et al, 1995b), in slow-growing compared to fast-growing species (Khurana and Singh, 2004;Tripathi and Raghubanshi, 2014), and in non-legumes compared to legumes (Tripathi and Raghubanshi, 2014). However, not all of these generalizations are consistent among studies.…”

Section: Figure 1 | Conceptual Model Of How Nitrogen Addition Affectsmentioning

confidence: 97%

Nutrient addition effects on tropical dry forests: a mini-review from microbial to ecosystem scales

et al. 2015

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Humans have more than doubled inputs of reactive nitrogen globally and greatly accelerated the biogeochemical cycles of phosphorus and metals. However, the impacts of increased element mobility on tropical ecosystems remain poorly quantified, particularly for the vast tropical dry forest biome. Tropical dry forests are characterized by marked seasonality, relatively little precipitation, and high heterogeneity in plant functional diversity and soil chemistry. For these reasons, increased nutrient deposition may affect tropical dry forests differently than wet tropical or temperate forests. Here, we review studies that investigated how nutrient availability affects ecosystem and community processes from the microsite to ecosystem scales in tropical dry forests. The effects of N and P addition on ecosystem carbon cycling and plant and microbial dynamics depend on forest successional stage, soil parent material, and rainfall regime. Responses may depend on whether overall productivity is N-vs. P-limited, although data to test this hypothesis are limited. These results highlight the many important gaps in our understanding of tropical dry forest responses to global change. Large-scale experiments are required to resolve these uncertainties.

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“…Previous studies that have investigated the nature of nutrient limitation of savanna vegetation have largely tended to focus on the herbaceous component of savannas (Barger, D'Antonio, Ghneim, Brink, & Cuevas, 2002;Bustamante et al, 2012;Cech, Kuster, Edwards, & Venterink, 2008;Copeland, Bruna, Silva, Mack, & Vasconcelos, 2012;Craine, Morrow, & Stock, 2008;Ludwig, de Kroon, Prins, & Berendse, 2001;O'Halloran et al, 2010;Ries & Shugart, 2008). Studies that have considered savanna trees have typically evaluated woody vegetation responses to the addition of a single nutrient (Kraaij & Ward, 2006;Wang, Katjiua, D'Odorico, & Okin, 2012), or the combined addition of N and P (Barbosa et al, 2014;van Der Waal et al, 2009;Khurana & Singh, 2004;Vadigi & Ward, 2013), thereby precluding identification of the specific nutrient(s) limiting growth (but see Wang et al, 2012;Holdo, 2013). Results from these earlier studies suggest contrasting patterns of nutrient limitation of herbaceous vegetation across the diverse savannas of the world, ranging from nutrients not being limiting (O'Halloran et al, 2010), to grass growth being N-limited (Cech et al, 2008;Wang et al, 2012), P-limited (Ludwig et al, 2001), or colimited by N and P (Cech et al, 2008;Craine et al, 2008).…”

Section: Nodulation In N-fixersmentioning

confidence: 99%

“…N‐fixing and non‐N‐fixing species differ inherently in their nutritional requirements, leaf chemistry, and physiology (Pearson & Vitousek, ; Powers & Tiffin, ; Vitousek, Menge, Reed, & Cleveland, ; Vitousek et al., ), and thus may be expected to respond differently to increases in N and P availability (Barbosa et al., ; Cramer, Chimphango, Van Cauter, Waldram, & Bond, ; Cramer, Van Cauter, & Bond, ; Khurana & Singh, ). N‐fixing plants have tissues that are richer in N than non‐N‐fixers due to their association with N‐fixing bacteria in root nodules.…”

Section: Introductionmentioning

confidence: 99%

“…Nutrient deposition can also affect the composition of tree communities if increased nutrient availability has differing effects on the dominant tree functional types that characterize these ecosystems, namely, N-fixers and non-N-fixers. N-fixing and non-N-fixing species differ inherently in their nutritional requirements, leaf chemistry, and physiology (Pearson & Vitousek, 2002;Powers & Tiffin, 2010;Vitousek, Menge, Reed, & Cleveland, 2013;Vitousek et al, 2002), and thus may be expected to respond differently to increases in N and P availability (Barbosa et al, 2014;Cramer, Chimphango, Van Cauter, Waldram, & Bond, 2007;Cramer, Van Cauter, & Bond, 2010;Khurana & Singh, 2004). N-fixing plants have tissues that are richer in N than non-N-fixers due to their association with N-fixing bacteria in root nodules.…”

Section: Introductionmentioning

confidence: 99%

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Effects of increased N and P availability on biomass allocation and root carbohydrate reserves differ between N‐fixing and non‐N‐fixing savanna tree seedlings

Varma

Catherin

Sankaran

2018

Ecology and Evolution

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In mixed tree‐grass ecosystems, tree recruitment is limited by demographic bottlenecks to seedling establishment arising from inter‐ and intra‐life‐form competition, and disturbances such as fire. Enhanced nutrient availability resulting from anthropogenic nitrogen (N) and phosphorus (P) deposition can alter the nature of these bottlenecks by changing seedling growth and biomass allocation patterns, and lead to longer‐term shifts in tree community composition if different plant functional groups respond differently to increased nutrient availability. However, the extent to which tree functional types characteristic of savannas differ in their responses to increased N and P availability remains unclear. We quantified differences in above‐ and belowground biomass, and root carbohydrate contents in seedlings of multiple N‐fixing and non‐N‐fixing tree species characteristic of Indian savanna and dry forest ecosystems in response to experimental N and P additions. These parameters are known to influence the ability of plants to compete, as well as survive and recover from fires. N‐fixers in our study were co‐limited by N and P availability, while non‐N‐fixers were N limited. Although both functional groups increased biomass production following fertilization, non‐N‐fixers were more responsive and showed greater relative increases in biomass with fertilization than N‐fixers. N‐fixers had greater baseline investment in belowground resources and root carbohydrate stocks, and while fertilization reduced root:shoot ratios in both functional groups, root carbohydrate content only reduced with fertilization in non‐N‐fixers. Our results indicate that, even within a given system, plants belonging to different functional groups can be limited by, and respond differentially to, different nutrients, suggesting that long‐term consequences of nutrient deposition are likely to vary across savannas contingent on the relative amounts of N and P being deposited in sites.

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Impact of elevated nitrogen inputs on seedling growth of five dry tropical tree species as affected by life-history traits

Cited by 14 publications

References 31 publications

Plant responses to nutrient addition experiments conducted in tropical forests

Plant responses to nutrient addition experiments conducted in tropical forests

Nutrient addition effects on tropical dry forests: a mini-review from microbial to ecosystem scales

Effects of increased N and P availability on biomass allocation and root carbohydrate reserves differ between N‐fixing and non‐N‐fixing savanna tree seedlings

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