Productivity, resource use, and competitive interactions of Fraxinus uhdei in Hawaii uplands

2001 ◽  
Vol 31 (1) ◽  
pp. 132-142 ◽  
Author(s):  
Adrián Ares ◽  
James H Fownes

We examined stand growth, canopy development, and resource use of Fraxinus uhdei (Wenzig) Lingelsh, a nonindigenous tree grown in Hawaii, and its interactions with the native, N-fixing tree Acacia koa Gray. Along a gradient of decreasing rainfall with elevation, on Histosols, F. uhdei had decreased stand basal area, productivity, and canopy development. At high-elevation sites, productivity of F. uhdei was limited by N, and F. uhdei benefitted from association with A. koa, as (i) foliar N content of F. uhdei was positively related to aboveground net primary productivity (ANPP), (ii) leaf area index, biomass increment, and ANPP of F. uhdei increased in a single-species stand after N additions, but there was no response by either F. uhdei or A. koa in a mixed stand, and (iii) productivity of F. uhdei in mixed stands with A. koa at high-elevation sites was greater than in single-species stands, and F. uhdei foliage was enriched with N in proportion to the fraction of stand basal area in A. koa. Seemingly, growth of F. uhdei on Histosols was also limited by water availability, as an index of carbon isotope composition of leaves (δ13C), and, therefore, intrinsic water-use efficiency (WUE) increased with elevation. Biomass production of F. uhdei stands per unit leaf area and per unit intercepted radiation (ε) decreased with increasing elevation on Histosols. Decreased nitrogen-use efficiency and ε of F. uhdei on Histosols were both traded off against increased WUE.

2017 ◽  
Vol 389 ◽  
pp. 285-295 ◽  
Author(s):  
Eladio H. Cornejo-Oviedo ◽  
Steven L. Voelker ◽  
Douglas B. Mainwaring ◽  
Douglas A. Maguire ◽  
Frederick C. Meinzer ◽  
...  

1985 ◽  
Vol 15 (5) ◽  
pp. 985-988 ◽  
Author(s):  
Ram Oren ◽  
Walter G. Thies ◽  
Richard H. Waring

Total stand sapwood basal area, a measure of competing canopy leaf area, was reduced 30% by laminated root rot induced by Phellinusweirii (Murr.) Gilb. in a heavily infected 40-year-old coastal stand of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) compared with that of a similar uninfected stand. Annual basal area increment per unit of sapwood area, an index of tree vigor, was expected to increase in uninfected trees in the infected stand as surrounding trees died from root rot; vigor of the uninfected trees did increase by an average of 30%, offsetting the reduction in canopy leaf area. This increase, although less than might be expected in an evenly spaced thinned stand, was sufficient to maintain stand basal area growth at levels similar to those of unthinned forests. These findings indicate that increased growth by residual trees must be taken into account when the impact of disease-induced mortality on stand production is assessed.


2021 ◽  
Vol 118 (52) ◽  
pp. e2118052118
Author(s):  
Steven A. Kannenberg ◽  
Avery W. Driscoll ◽  
Paul Szejner ◽  
William R. L. Anderegg ◽  
James R. Ehleringer

Globally, intrinsic water-use efficiency (iWUE) has risen dramatically over the past century in concert with increases in atmospheric CO2 concentration. This increase could be further accelerated by long-term drought events, such as the ongoing multidecadal “megadrought” in the American Southwest. However, direct measurements of iWUE in this region are rare and largely constrained to trees, which may bias estimates of iWUE trends toward more mesic, high elevation areas and neglect the responses of other key plant functional types such as shrubs that are dominant across much of the region. Here, we found evidence that iWUE is increasing in the Southwest at one of the fastest rates documented due to the recent drying trend. These increases were particularly large across three common shrub species, which had a greater iWUE sensitivity to aridity than Pinus ponderosa, a common tree species in the western United States. The sensitivity of both shrub and tree iWUE to variability in atmospheric aridity exceeded their sensitivity to increasing atmospheric [CO2]. The shift to more water-efficient vegetation would be, all else being equal, a net positive for plant health. However, ongoing trends toward lower plant density, diminished growth, and increasing vegetation mortality across the Southwest indicate that this increase in iWUE is unlikely to offset the negative impacts of aridification.


Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1093
Author(s):  
Juan Pedro Ferrio ◽  
Tatiana A. Shestakova ◽  
Jorge del Castillo ◽  
Jordi Voltas

In the Mediterranean, mixed forests of Aleppo pine and holm oak are widespread. Generally considered a transition stage in the succession towards climax oak communities, niche segregation may also contribute to the prevalence of these communities. So far, there is increasing evidence of hydrological niche segregation, with the two species showing complementary water use and seasonal growth patterns. However, it remains unknown whether interspecific interactions affect the response to climate and the mid-term (decadal) growth and water-use efficiency of pines and oaks in mixed stands. Here, we combined tree-ring chronologies, built on different competition classes within a mixed stand, with a spatially explicit assessment of individual growth and wood carbon isotope discrimination (∆13C), as a proxy of intrinsic water-use efficiency, and compared these results with previously reported water uptake patterns. We found that competition with pines modulated the climate response of oaks, whereas pine climate response was insensitive to competition. On the other hand, pine density affected only pine growth, whereas oak competition affected both species. We conclude that the presence of pines had negligible or even positive effects on the oaks, but competition with neighbor oaks limited their ability to recover after drought. Conversely, pines experienced greater drought stress under competition, with both oaks and pines.


Forests ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 558 ◽  
Author(s):  
Chan-Beom Kim ◽  
Yong Suk Kim ◽  
Hyung Tae Choi ◽  
Jeonghwan Kim ◽  
Seongjun Kim ◽  
...  

The Mongolian pine (Pinus sylvestris var. mongolica) is one of the most common tree species in semiarid and arid areas of China, especially in the sand dunes of the Hulunbeier steppe. This study addresses the morphological and physiological characteristics of the Mongolian pine according to sand dune height. Five sites were chosen with various sand dune heights (P1–P5). Nine years after planting, tree growth, leaf area, leaf mass per leaf unit area (LMA), diameter at breast height (DBH), tree height, diameter at root collar (DRC), longest shoot length, carbon isotope composition, and intrinsic water use efficiency (iWUE) were measured to explore the responses of Mongolian pine trees to drought. DBH, tree height, DRC, leaf area, leaf length, and longest shoot length significantly decreased with greater sand dune height (p < 0.05). However, the carbon isotope actually increased with dune height (p < 0.05). Conversely, the iWUE of current-year pine needles was significantly higher at measurement points P3 (132.29 μmol CO2 mol −1 H2O), P4 (132.96 μmol CO2 mol −1 H2O), and P5 (125.34 μmol CO2 mol −1 H2O) than at the lower points P1 (95.18 ± 9.87 μmol CO2 mol −1 H2O) and P2 (103.10 ± 11.12 μmol CO2 mol −1 H2O). Greater sand dune height increases the distance to groundwater, which in this study led to an increase in iWUE in the Mongolian pines, thus these trees appear to adapt to increased sand dune height by increasing their iWUE and decreasing their leaf area. However, prolonged periods characterized by such adaptations can lead to tree death. We expect these findings to be useful when selecting plantation sites for Mongolian pines in semiarid and arid climates.


1994 ◽  
Vol 21 (2) ◽  
pp. 207 ◽  
Author(s):  
MV Gutierrez ◽  
FC Meinzer

In evergreen species, leaf carbon isotope discrimination (Δ) integrates phenological rhythms in gas exchange as well as seasonal changes in environmental conditions. However, few reports on long term variations in Δ of woody plants are available. We measured Δ, gas exchange, nitrogen content, and photosynthetic nitrogen-use efficiency (PNUE) in coffee hedgerows at different stages of canopy development encompassing a range of leaf area index (LAI) from 0.7 to 7.5. Assimilation was highest in sun leaves, but stomatal conductance was highest in shaded leaves. This resulted in a high correlation between assimilation and stomatal conductance in sun, but not in shaded leaves. Δ was about 20 lower in sun than in shaded leaves, and varied by 2.30 among leaves at different positions along two-year- old branches. These differences in Δ were the result of changes in carbon isotope composition that occurred in mature, fully expanded leaves as they became shaded during subsequent canopy growth. Results from a mass balance model based on leaf gas exchange characteristics and measured foliar Δ values suggested that about 50% of the carbon originally fixed during leaf development in the sun may have subsequently been turned over in the shade. Δ of sun leaves from the upper canopy decreased by about 20 with increasing LAI, indicating that intrinsic water-use efficiency (WUE) of this canopy layer increased during canopy development. In contrast, instantaneous WUE, estimated as assimilation divided by canopy transpiration obtained from sap flow measurements, seemed to decrease with increasing LAI. PNUE of upper canopy sun leaves decreased with increasing LAI, suggesting a physiological compromise between WUE and PNUE mediated by stomatal conductance, which also decreased with increasing LAI. A strong negative correlation obtained between leaf Δ and N content was consistent with a trade-off between intrinsic water- and N-use efficiency.


Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 47 ◽  
Author(s):  
Francesco Giammarchi ◽  
Pietro Panzacchi ◽  
Maurizio Ventura ◽  
Giustino Tonon

Increasing atmospheric CO2 concentration and nitrogen deposition are, among the global change related drivers, those playing a major role on forests carbon sequestration potential, affecting both their productivity and water-use efficiency. Up to now, results are however contrasting, showing that the processes underlying them are far from being fully comprehended. In this study, we adopted an innovative approach to simulate the increase of N deposition in a sessile oak forest in North-Eastern Italy, by fertilizing both from above and below the canopy. We observed the dynamics of basal area increment, intrinsic water-use efficiency and of several leaf functional traits over 4 years, to evaluate how the added nitrogen and the two different fertilization system could affect them. We were not able, however, to detect any shift, besides a common yearly variability related to a prevailing background environmental forcing. To this end, we considered as relevant factors both the short time-span of the observation and the relatively low rate of applied nitrogen. Therefore, we stress the importance of long-term, manipulative experiments to improve the understanding of the C sequestration and mitigation ability of forests in response to increased N deposition.


Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1702
Author(s):  
Xing Pu ◽  
Xiaochun Wang ◽  
Lixin Lyu

Tree growth in high-elevation forests may increase as a result of increasing temperatures and CO2 concentrations in the atmosphere (Ca). However, the pattern and the physiological mechanism on how these two factors interact to affect tree growth are still poorly understood. Here, we analyzed the temporal changes in radial growth and tree-ring δ13C for Picea and Abies trees growing in both treeline and lower-elevation forests on the Tibetan Plateau. We found that the tree growth at the treeline has significantly accelerated during the past several decades but has remained largely stable or slightly declined at lower elevations. Further results based on tree-ring δ13C suggest that intrinsic water-use efficiency (iWUE) was generally higher at the treeline than in lower-elevation forests, although increasing trends of iWUE existed for all sites. This study demonstrated that the synergetic effects of elevated Ca and increasing temperatures have increased tree growth at the treeline but may not lead to enhanced tree growth in lower-elevation forests due to drought stress. These results demonstrate the elevational dependence of tree growth responses to climatic changes in high-elevation forests from a physiologically meaningful perspective.


2019 ◽  
Author(s):  
Marina Caselli ◽  
Gabriel Ángel Loguercio ◽  
María Florencia Urretavizcaya ◽  
Guillermo Emilio Defossé

Abstract Leaf area is an important ecophysiological and silvicultural variable for quantifying the potential production of trees, since it can represent growing space occupancy. At the stand level in mixed forests, productivity is conditioned on how growing space is distributed among different components structure, such as species and strata. In complex structures, traditional forest variables (i.e., basal area) do not allow a good representation of the occupied growing space, whereas leaf area appears as a better indicator. Andean cypress and coihue beech are species of the Andean-Patagonian forests that grow in either pure or mixed stands, presenting high productive potential. The aim of this study was to develop, for each species, leaf area prediction functions through allometric relations and to evaluate the relation between leaf area, volume increment and growing space occupancy. For this purpose, we carried out destructive sampling of individuals of both species in mixed Andean cypress-coihue forests. Results for these species show that leaf area can be reliably estimated by using the models developed in this study. These models, based on sapwood area, tree diameter, and/or height measurements, explain at least 90 percent of variation in leaf area. The functions fitted are a fundamental tool to study the distribution of growth and to formulate management guidelines for mixed forests through the control of growing space occupancy using leaf area index.


Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 441
Author(s):  
Yang Liu ◽  
Mao Yang ◽  
Chunsheng Yao ◽  
Xiaonan Zhou ◽  
Wei Li ◽  
...  

Excessive nitrogen (N) application rates and serious over-exploitation of groundwater under farmer practice threatens the sustainable use of resources in the North China Plain (NCP). Crop canopy structure affects light distribution between leaves, which is important to determine crop growth. A field experiment conducted from October 2016 to June 2019 in the NCP was designed to examine whether optimum water and nitrogen management could optimize canopy characteristics to improve yield and resource use efficiency. Field treatments included: (1) an example of local farming practices, which include the addition of 330 kg N ha−1 and irrigated twice (FP), (2) a reduced N rate of 270 kg N ha−1 and irrigated twice (T1), (3) a reduced rate of N rate of 210 kg N ha−1 and irrigated once (T2), and (4) no N applied (0 kg N ha−1) and irrigated once (T3). Results showed that the highest yield was in T1 treatment during 3 years’ winter wheat growing seasons. Water use efficiency (WUE), N use efficiency (NUtE), and N partial factor productivity (PFPN) were significantly higher in T2 treatment than in FP, and the three-year average yield was 9.4% higher than that at FP. Optimum crop management practice (T1 and T2) improved canopy structure characteristics, with less relative photosynthetically active photon flux density (PPFD) penetrated of canopy and higher population uniformity as well as leaf area index, to coordinate the distribution of light within the canopy and maximize canopy light interception, resulting in higher yield and resource use efficiency. Leaf area index (LAI) and specific leaf area (SLA) were closely correlated with grain yield and WUE, while PPFD penetrated of canopy was negatively and significantly correlated with grain yield and WUE. The results indicate that canopy structure characteristics, especially PPFD and population uniformity are good indicators of yield and resource use efficiency.


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