scholarly journals Competition for water and species coexistence in phenologically structured annual plant communities

2021 ◽  
Author(s):  
Jacob I Levine ◽  
Jonathan M Levine ◽  
Theo Gibbs ◽  
Stephen W Pacala
Keyword(s):  
Growth Rate ◽  
Species Coexistence ◽  
Empirical Studies ◽  
Growing Season ◽  
Annual Plant ◽  
Growing Season Length ◽  
Access To Water ◽  
Drying Conditions ◽  
Annual Plant Species ◽  
High Diversity

Both competition for water and phenological variation are important determinants of plant community structure, but ecologists lack a synthetic theory for how they affect coexistence outcomes. We developed an analytically tractable model of water competition for Mediterranean annual communities and demonstrate that variation in phenology alone can maintain high diversity in spatially homogenous assemblages of water-limited plants. We modeled a system where all water arrives early in the season and species vary in their ability to grow under drying conditions. As a consequence, species differ in growing season length, and compete by shortening the growing season of their competitors. This model replicates and offers mechanistic explanations for qualitative patterns observed in prior empirical studies of how phenology influences coexistence among Mediterranean annuals. Additionally, we found that a decreasing, concave-up tradeoff between growth rate and access to water can theoretically maintain infinite diversity under simple but realistic assumptions. High diversity is possible because: 1) later plants escape competition after their earlier-season competitors have gone to seed and 2) early- season species are more than compensated for their shortened growing season by a growth-rate advantage. Together, these mechanisms provide an explanation for how annual plant species might coexist when competing only for water.

Growth rate rather than growing season length determines wood biomass in dry environments

2019 ◽  
Vol 271 ◽  
pp. 46-53 ◽  
Author(s):  
Ping Ren ◽  
Emanuele Ziaco ◽  
Sergio Rossi ◽  
Franco Biondi ◽  
Peter Prislan ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growing Season ◽  
Wood Biomass ◽  
Season Length ◽  
Growing Season Length

Vegetation control and site preparation affect patterns of shoot elongation for 3-year-old loblolly pine

1993 ◽  
Vol 23 (10) ◽  
pp. 2110-2115 ◽  
Author(s):  
H. Lee Allen ◽  
Thomas R. Wentworth
Keyword(s):  
Growth Rate ◽  
Weed Control ◽  
Loblolly Pine ◽  
Growing Season ◽  
Shoot Elongation ◽  
Height Growth ◽  
Site Preparation ◽  
Intensive Culture ◽  
Vegetation Control ◽  
Growing Season Length

Effects of vegetation control and site preparation on the magnitude, morphology, and phenology of loblolly pine (Pinustaeda L.) height growth were investigated duing the third growing season following planting in the Piedmont of North Carolina. Biweekly measurements were made of shoot elongation (by flush) throughout the growing season on a subsample of trees within three replicated plots receiving a factorial combination of site preparation (chop versus shear, pile, disk) and weed control (none, partial control with herbicide, and complete control by hand weeding) treatments. Cumulative height growth on the most intensively treated plots was twice that found on the chopped-only plots, with weed control having a more pronounced positive effect than intensive site preparation. Superior height growth resulted principally from greater length per flush but also from an increased number of flushes. Trees on plots where vegetation was controlled averaged between four and five flushes compared with trees on chopped-only plots, which averaged three flushes. As growth rate of one flush slowed, growth rate of the subsequent flush accelerated, resulting in a rather uniform elongation rate for the shoot apex throughout most of the growing season. Treatment effects on the seasonal distribution of growth and on growing season length were minimal. Thus, intensive culture influenced shoot growth rates and morphology, but not phenology. Apparently the effect of intensive culture was to improve the availability of limited environmental resources and, consequently, to increase growth rate throughout the growing season.

scholarly journals Growing‐season length and soil microbes influence the performance of a generalist bunchgrass beyond its current range

Ecology ◽  
2020 ◽  
Vol 101 (9) ◽  
Author(s):  
Clifton P. Bueno de Mesquita ◽  
Samuel A. Sartwell ◽  
Steven K. Schmidt ◽  
Katharine N. Suding
Keyword(s):  
Soil Microbes ◽  
Growing Season ◽  
Season Length ◽  
Current Range ◽  
Growing Season Length

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%.

Walleye (Stizostedion vitreum vitreum) and Yellow Perch (Perca flavescens) Populations and Fisheries of the Red Lakes, Minnesota, 1930–75

1977 ◽  
Vol 34 (10) ◽  
pp. 1774-1783 ◽  
Author(s):  
Lloyd L. Smith Jr.
Keyword(s):  
Growth Rate ◽  
Yellow Perch ◽  
Climatic Factors ◽  
Perca Flavescens ◽  
Growing Season ◽  
Commercial Fishery ◽  
Class Strength ◽  
Parent Stock ◽  
Catch Statistics

In an investigation of the commercial fishery of Red Lakes, Minnesota, for the 46-yr period 1930–75, catch statistics were analyzed, and the dynamics of the perch and walleye populations were examined. Mean annual yields of walleye for two statistical periods, 1930–53 and 1954–75, were 309,900 and 245,100 kg, respectively for walleyes, and 96,400 and 109,500 kg for perch. Annual abundance (CPE based on average catches per day per 5-net units of gill nets) varied from 3.8 to 64.6 kg for walleye, and from 2.5 to 34.4 kg for perch. Causes of fluctuations in harvestable stock were directly related to strength of year-classes and to growth rate during the season of capture. Year-class strength was not related to the abundance of parent stock or of potential predators. The respective strengths of year-classes of perch and walleye in the same year were positively correlated (r = 0.859, P < 0.01), and are directly related to climatic factors. Growth rate of walleye in different calendar years varied from +30.7 to −42.2% of mean growth, and that of perch from +13.4 to −8.6% (1941–56). Growing season began in mid-June and was almost over by September 1. Walleye yield could be enhanced by starting harvest July 1 instead of early June. Perch yield could be improved by harvesting small perch. Key words: Percidae, Perca, population dynamics, Stizostedion, long-term yield

scholarly journals Seed mass effects on germination and growth of diverse European Scots pine populations

1994 ◽  
Vol 24 (2) ◽  
pp. 306-320 ◽  
Author(s):  
P.B. Reich ◽  
J. Oleksyn ◽  
M.G. Tjoelker
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Scots Pine ◽  
Field Experiments ◽  
Seed Mass ◽  
Growing Season ◽  
Turkish Population ◽  
Dry Mass ◽  
Relative Growth ◽  
Mass Effects

Seedlings of 24 European Scots pine (Pinussylvestris L.) populations were grown in controlled environment chambers under simulated photoperiodic conditions of 50 and 60°N latitude to evaluate the effect of seed mass on germination and seedling growth characteristics. Seeds of each population were classified into 1-mg mass classes, and the four classes per population with the highest frequencies were used. Photoperiod had minimal influence on seed mass effects. Overall, seed mass was positively related to the number of cotyledons and hypocotyl height. Populations differed significantly in seed mass effect on biomass. In northern populations (55–61°N), dry mass at the end of the first growing season was little affected by seed mass. However, dry mass in 9 of 15 central populations (54–48°N) and all southern (<45°N) populations correlated positively with seed mass. Relative growth rate was not related to seed mass within or across populations, and thus early growth is largely determined by seed mass. Relative growth rate also did not differ among populations, except for a geographically isolated Turkish population with the highest seed mass and lowest relative growth rate. After one growing season, height was positively correlated (r2 > 0.6) with seed mass in 15 populations. To check the duration of seed mass effects, height growth of 1- to 7-year-old field experiments established with the same seed lots were compared. Seed mass effects on height were strongest for 1-year-old seedlings and declined or disappeared by the age of 5–7 years among central and southern populations, but remained stable over that time in northern populations.

Exploring the variation in ecosystem scale methane fluxes and its drivers within a boreal mire complex

2021 ◽  
Author(s):  
Koffi Dodji Noumonvi ◽  
Joshua L. Ratcliffe ◽  
Mats Öquist ◽  
Mats B. Nilsson ◽  
Matthias Peichl
Keyword(s):  
Eddy Covariance ◽  
Land Surface ◽  
Chemical Properties ◽  
Growing Season ◽  
Small Scale ◽  
Atmospheric Methane ◽  
Flux Footprint ◽  
Growing Season Length ◽  
Methane Fluxes ◽  
Northern Peatlands

&lt;p&gt;Northern peatlands cover a small fraction of the earth&amp;#8217;s land surface, and yet they are one of the most important natural sources of atmospheric methane. With climate change causing rising temperatures, changes in water balance and increased growing season length, peatland contribution to atmospheric methane concentration is likely to increase, justifying the increased attention given to northern peatland methane dynamics. Northern peatlands often occur as heterogeneous complexes characterized by hydromorphologically distinct features from &lt; 1 m&amp;#178; to tens of km&amp;#178;, with differing physical, hydrological and chemical properties. The more commonly understood small-scale variation between hummocks, lawns and hollows has been well explored using chamber measurements. Single tower eddy covariance measurements, with a typical 95% flux footprint of &lt; 0.5 km&amp;#178;, have been used to assess the ecosystem scale methane exchange. However, how representative single tower flux measurements are of an entire mire complex is not well understood. To address this knowledge gap, the present study takes advantage of a network of four eddy covariance towers located less than 3 km apart at four mires within a typical boreal mire complex in northern Sweden. The variation of methane fluxes and its drivers between the four sites will be explored at different temporal scales, i.e. half-hourly, daily and at a growing-season scale.&lt;/p&gt;

On the Effectiveness of Growth- Enhancing Policies in a Model of Growth Without Scale Effects

2002 ◽  
Vol 3 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Lutz G. Arnold
Keyword(s):  
Economic Growth ◽  
Growth Rate ◽  
Human Capital ◽  
Population Growth ◽  
Capital Accumulation ◽  
Scale Effects ◽  
Growth Models ◽  
Empirical Studies ◽  
Human Capital Accumulation ◽  
Accelerate Growth

Abstract Standard R&D growth models have two disturbing properties: the presence of scale effects (i.e., the prediction that larger economies grow faster) and the implication that there is a multitude of growth-enhancing policies. Recent models of growth without scale effects, such as Segerstrom's (1998), not only remove the counterfactual scale effect, but also imply that the growth rate does not react to any kind of economic policy. They share a different disturbing property, however: economic growth depends positively on population growth, and the economy cannot grow in the absence of population growth. The present paper integrates human capital accumulation into Segerstrom's (1998) model of growth without scale effects. Consistent with many empirical studies, growth is positively related not to population growth, but to investment in human capital. And there is one way to accelerate growth: subsidizing education.

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