scholarly journals Comparison of Intra-Annual Xylem and Phloem Formation of Picea crassifolia Stands at Two Latitudes in Northwest China

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1445
Author(s):  
Biyun Yu ◽  
Xuebin Li ◽  
Ping Zhao ◽  
Jianguo Huang
Keyword(s):  
Climate Change ◽  
Growing Season ◽  
Maximum Growth ◽  
Northwest China ◽  
Maximum Growth Rate ◽  
Wall Thickening ◽  
Low Latitude ◽  
Picea Crassifolia ◽  
Trade Offs ◽  
Semi Arid

Understanding the changes in xylem and phloem formation of trees and their relationship along latitudes are important for evaluating and predicting how fragile forests may respond to climate change; however, corresponding studies are still relatively scarce. This study investigated the intra-annual dynamics of xylem and phloem formation of Picea crassifolia and their relationship at two latitudes of arid and semi-arid forests in China. The results showed that both xylem and phloem formation varied at different latitudes. Xylem formation at the low-latitude site (Luoshan) started two weeks earlier than that at the high-latitude site (Helanshan) but ended one week later, resulting in an extended growing season at the low-latitude site. Phloem formation preceded cambium activity and xylogenesis at both sites by 24.6 days in Luoshan, which had warmer conditions, and by 17.3 days in Helanshan. In Luoshan, compared to Helanshan, there occurred significantly more enlarging and wall thickening cells, during (relatively wet) June–August, but significantly fewer enlarging and wall thickening cells as well as total xylem cells, during (relatively dry) April–May. Sample trees produced significantly fewer early phloem cells during the early growing season (April–May) in Luoshan, but generated significantly more late phloem cells during the late growing season in Helanshan. Additionally, different trade-offs between xylem and phloem formation were observed at different sites. The longer duration of early phloem formation might have shortened the duration of xylem lignification in Helanshan; in Luoshan, the date that late phloem reached its maximum growth rate was significantly positively correlated with the date when xylem lignification ended. The results revealed the plasticity of xylem and phloem formation under changing environmental conditions and a complex and site-specific relationship between xylem and phloem formation. These findings could help us better understand and predict the future growth of arid and semi-arid forests in China in response to climate change.

scholarly journals Comparison of the Radial Growth Response of Picea crassifolia to Climate Change in Different Regions of the Central and Eastern Qilian Mountains

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1015
Author(s):  
Xuan Wu ◽  
Liang Jiao ◽  
Dashi Du ◽  
Changliang Qi ◽  
Ruhong Xue
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Central Region ◽  
Radial Growth ◽  
Growing Season ◽  
Qilian Mountains ◽  
Growth Patterns ◽  
Total Precipitation ◽  
Picea Crassifolia ◽  
The Qilian Mountains

It is important to explore the responses of radial tree growth in different regions to understand growth patterns and to enhance forest management and protection with climate change. We constructed tree ring width chronologies of Picea crassifolia from different regions of the Qilian Mountains of northwest China. We used Pearson correlation and moving correlation to analyze the main climate factors limiting radial growth of trees and the temporal stability of the growth–climate relationship, while spatial correlation is the result of further testing the first two terms in space. The conclusions were as follows: (1) Radial growth had different trends, showing an increasing followed by a decreasing trend in the central region, a continuously increasing trend in the eastern region, and a gradually decreasing trend in the isolated mountain. (2) Radial tree growth in the central region and isolated mountains was constrained by drought stress, and tree growth in the central region was significantly negatively correlated with growing season temperature. Isolated mountains showed a significant negative correlation with mean minimum of growing season and a significant positive correlation with total precipitation. (3) Temporal dynamic responses of radial growth in the central region to the temperatures and SPEI (the standardized precipitation evapotranspiration index) in the growing season were unstable, the isolated mountains to total precipitation was unstable, and that to SPEI was stable. The results of this study suggest that scientific management and maintenance plans of the forest ecosystem should be developed according to the response and growth patterns of the Qinghai spruce to climate change in different regions of the Qilian Mountains.

Reassessment of Maximum Growth Rates for C3 and C4 Crops

1978 ◽  
Vol 14 (1) ◽  
pp. 1-5 ◽  
Author(s):  
J. L. Monteith
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growing Season ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Crop Growth ◽  
Close Inspection ◽  
Similar Difference ◽  
Photosynthetic Efficiencies

SUMMARYFigures for maximum crop growth rates, reviewed by Gifford (1974), suggest that the productivity of C3 and C4 species is almost indistinguishable. However, close inspection of these figures at source and correspondence with several authors revealed a number of errors. When all unreliable figures were discarded, the maximum growth rate for C3 stands fell in the range 34–39 g m−2 d−1 compared with 50–54 g m−2 d−1 for C4 stands. Maximum growth rates averaged over the whole growing season showed a similar difference: 13 g m−2 d−1 for C3 and 22 g m−2 d−1 for C4. These figures correspond to photosynthetic efficiencies of approximately 1·4 and 2·0%.

scholarly journals Can climate change influence agricultural GTFP in arid and semi-arid regions of Northwest China?

2020 ◽  
Vol 12 (5) ◽  
pp. 837-853
Author(s):  
Jian Feng ◽  
Lingdi Zhao ◽  
Yibo Zhang ◽  
Lingxiao Sun ◽  
Xiang Yu ◽  
...  
Keyword(s):  
Climate Change ◽  
Arid Regions ◽  
Northwest China ◽  
Semi Arid

scholarly journals Trait-based approach to bacterial growth efficiency

2018 ◽  
Author(s):  
Mario E. Muscarella ◽  
Xia Meng Howey ◽  
Jay T. Lennon
Keyword(s):  
Growth Rate ◽  
Bacterial Growth ◽  
Maximum Growth ◽  
Growth Efficiency ◽  
Maximum Growth Rate ◽  
Bacterial Growth Efficiency ◽  
Species Identity ◽  
Trade Offs ◽  
Aggregate Property ◽  
Resource Type

AbstractBacterial growth efficiency (BGE) is the proportion of assimilated carbon that is converted into biomass and reflects the balance between growth and energetic demands. Often measured as an aggregate property of the community, BGE is highly variable within and across ecosystems. To understand this variation, we first identified how species identity and resource type affect BGE using 20 bacterial isolates belonging to the phylum Proteobacteria that were enriched from north temperate lakes. Using a trait-based approach that incorporated genomic and phenotypic information, we characterized the metabolism of each isolate and tested for predicted trade-offs between growth rate and efficiency. A substantial amount of variation in BGE could be explained at both broad (i.e., order, 20 %) and fine (i.e., strain, 58 %) taxonomic levels. While resource type was a relatively weak predictor across species, it explained > 60 % of the variation in BGE within a given species. Furthermore, a metabolic trade-off (between maximum growth rate and efficiency) and genomic features revealed that BGE is a predictable metabolic feature. Our study suggests that genomic and phylogenetic information may help predict aggregate microbial community functions like BGE and the fate of carbon in ecosystems.Originality and SignificanceBacterial growth efficiency (BGE) is an important yet notoriously variable measure of metabolism that has proven difficult to predict. To better understand how assimilated carbon is allocated, we explored growth efficiency across a collection of bacteria strains using a trait-based approach. Specifically, we measured respiration and biomass formation rates for populations grown in minimal media containing one of three carbon resources. In addition, we collected a suite of physiological traits to describe each strain, and we sequenced the genome of each organism. Our results suggest that species identity and resource type may contribute to growth efficiency when measured as an aggregate property of a natural community. In addition, we identified genomic pathways that are associated with elevated BGE. The findings have implications for integrating microbial metabolism from the cellular to ecosystem scale.

scholarly journals Restoration of degraded grasslands, but not invasion by Prosopis juliflora, avoids trade-offs between climate change mitigation and other ecosystem services

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Purity Rima Mbaabu ◽  
Daniel Olago ◽  
Maina Gichaba ◽  
Sandra Eckert ◽  
René Eschen ◽  
...  
Keyword(s):  
Climate Change ◽  
Ecosystem Services ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Climate Change Mitigation ◽  
Arid Regions ◽  
Prosopis Juliflora ◽  
Trade Offs ◽  
Change Mitigation ◽  
Semi Arid

AbstractGrassland degradation and the concomitant loss of soil organic carbon is widespread in tropical arid and semi-arid regions of the world. Afforestation of degraded grassland, sometimes by using invasive alien trees, has been put forward as a legitimate climate change mitigation strategy. However, even in cases where tree encroachment of degraded grasslands leads to increased soil organic carbon, it may come at a high cost since the restoration of grassland-characteristic biodiversity and ecosystem services will be blocked. We assessed how invasion by Prosopis juliflora and restoration of degraded grasslands in a semi-arid region in Baringo, Kenya affected soil organic carbon, biodiversity and fodder availability. Thirty years of grassland restoration replenished soil organic carbon to 1 m depth at a rate of 1.4% per year and restored herbaceous biomass to levels of pristine grasslands, while plant biodiversity remained low. Invasion of degraded grasslands by P. juliflora increased soil organic carbon primarily in the upper 30 cm and suppressed herbaceous vegetation. We argue that, in contrast to encroachment by invasive alien trees, restoration of grasslands in tropical semi-arid regions can both serve as a measure for climate change mitigation and help restore key ecosystem services important for pastoralists and agro-pastoralist communities.

scholarly journals Size evolution in microorganisms masks trade-offs predicted by the growth rate hypothesis

2016 ◽  
Vol 283 (1845) ◽  
pp. 20162272 ◽  
Author(s):  
Isabelle Gounand ◽  
Tanguy Daufresne ◽  
Dominique Gravel ◽  
Corinne Bouvier ◽  
Thierry Bouvier ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cell Size ◽  
Competitive Ability ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Strong Positive Correlation ◽  
Competitive Strategies ◽  
Growth Rate Hypothesis ◽  
Trade Offs ◽  
Size Evolution

Adaptation to local resource availability depends on responses in growth rate and nutrient acquisition. The growth rate hypothesis (GRH) suggests that growing fast should impair competitive abilities for phosphorus and nitrogen due to high demand for biosynthesis. However, in microorganisms, size influences both growth and uptake rates, which may mask trade-offs and instead generate a positive relationship between these traits (size hypothesis, SH). Here, we evolved a gradient of maximum growth rate ( μ max ) from a single bacterium ancestor to test the relationship among μ max , competitive ability for nutrients and cell size, while controlling for evolutionary history. We found a strong positive correlation between μ max and competitive ability for phosphorus, associated with a trade-off between μ max and cell size: strains selected for high μ max were smaller and better competitors for phosphorus. Our results strongly support the SH, while the trade-offs expected under GRH were not apparent. Beyond plasticity, unicellular populations can respond rapidly to selection pressure through joint evolution of their size and maximum growth rate. Our study stresses that physiological links between these traits tightly shape the evolution of competitive strategies.

scholarly journals Radial Growth Response of Picea crassifolia to Climatic Conditions in a Dryland Forest Ecosystem in Northwest China

Forests ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1382
Author(s):  
Hanxue Liang ◽  
Shaowei Jiang ◽  
Ali Muhammad ◽  
Jian Kang ◽  
Huoxing Zhu ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Ring ◽  
Air Temperature ◽  
Radial Growth ◽  
Northwest China ◽  
Climatic Conditions ◽  
Pinus Tabulaeformis ◽  
Future Climate Change ◽  
Picea Crassifolia ◽  
Maximum Air Temperature

As an important barrier against desert invasion in Northwest China, Helan Mountains (HL), Luoshan Mountains (LS) and their natural forests have an extremely important ecological status. It is of great significance to study the relationship between forest growth and climate in this region under the background of global change. At present, relevant research mostly focuses on the Chinese pine (Pinus tabulaeformis Carr.), and little is known about how Qinghai spruce (Picea crassifolia Kom.) responds to climate change. To investigate the potential relationships between radial growth of P. crassifolia and climatic conditions in Ningxia, China, we collected tree-ring samples from P. crassifolia growing in the HL and LS and then established the standard tree-ring width chronologies for the two sites. Correlation analysis together with multivariate linear regression and relative contribution analyses were used, and results showed that radial growth in the HL was determined by the precipitation in the previous September, by the standardized evapotranspiration index (SPEI) in the current March and June, and by the maximum air temperature in the current September. The maximum air temperature in the current September contributed the most (0.348) to the radial growth in the HL. In the LS, radial growth was determined by the precipitation in the previous September and in the current March and by the minimum air temperature in the current July. The factor that made the most contribution was the precipitation in the current March (0.489). Our results suggested that in the wetting and warming future, growth of P. crassifolia in the HL will increase while that in the LS needs further investigation. Our results also provide a basis for predicting how P. crassifolia in northwest China will grow under the background of future climate change and provide a reference for formulating relevant management measures to achieve ecological protection and sustainable development policies.

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