Early spring leaf out enhances growth and survival of saplings in a temperate deciduous forest.
ABSTRACT Saplings of many canopy tree species in winter deciduous forests receive the major portion of their light budget for their growing season prior to canopy closure in the spring. This period of high light may be critical for achieving a positive carbon (C) gain, thus contributing strongly to their growth and survival. This study of saplings of Aesculus glabra and Acer saccharum in Trelease Woods, Illinois, USA, tested this hypothesis experimentally by placing tents of shade cloth over saplings during their spring period of high light prior to canopy closure in three consecutive years. Leaf senescence began 16 days (year 0) and 60 days (year 1) earlier for shaded A. glabra saplings than control saplings. No change in senescence occurred for A. saccharum. The annual absolute growth in stem diameter of both species was negligible or negative for shaded saplings, but positive for control saplings. Only 7% of the shaded A. glabra saplings were alive after 2 years, while all control saplings survived for 3 years; only 20% of the shaded A. saccharum saplings survived for 3 years, while 73% of control saplings were alive after the same period. Early spring leaf out is a critical mechanism that allows the long-term persistence of saplings of these species in this winter deciduous forest. Studies and models of C gain, growth, and survival of saplings in deciduous forests may need to take into account their spring phenology because saplings of many species are actually "sun" individuals in the spring prior to their longer period in the summer shade.
SourceAvailable from: Lindsay M Dreiss[Show abstract] [Hide abstract]
ABSTRACT: Temperate forests represent one of the major biomes on Earth. They are most common in eastern North America, western and central Europe, and northeastern Asia, where the climate is defi ned by warm summers, cold winters, and intermediate levels of precipitation. To a lesser extent, they are also present in this same climate in Australia, New Zealand, South America, and South Africa. Temperate forests are dominated by either deciduous or evergreen canopies. In temperate deciduous forests, more commonly found in the Northern Hemisphere, plants drop their leaves in autumn, allowing for high seasonal variation in light availability to the understory. By contrast, in temperate evergreen forests, which are more commonly found in the Southern Hemisphere, plants keep their leaves year round. The temperate forest biome is rich in geologic and anthropocentric history, with much of the land shaped by glacial and human activity. Located in some of the most industrialized places in the world, temperate forests have been instrumental to socioeconomic development in these regions. As a consequence, these forests have been heavily impacted by expanding human populations, which remain the primary continuous threat to the structure and function of these forests.Encyclopedia of Natural Resources Vol I, 1st edited by Yeqiao Wang, 07/2014: chapter Forests: Temperate Evergreen and Deciduous: pages 214-223; CRC Press., ISBN: 978-1439852583
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ABSTRACT: We studied interannual variations in single-leaf phenology, i.e., temporal changes in leaf ecophysiological parameters that are responsible for forest canopy function, in a cool-temperate deciduous broadleaf forest at Takayama, central Japan. We conducted long-term in situ research from 2003 to 2010 (excluding 2008). We measured leaf mass per unit area (LMA), leaf chlorophyll and nitrogen contents, and leaf photosynthetic and respiratory characteristics [dark respiration, light-saturated photosynthetic rate (A max), maximum carboxylation rate (V cmax), and electron transport rate (J max)] of leaves of mature canopy trees of Betula ermanii Cham. and Quercus crispula Blume, from leaf expansion to senescence. All leaf characteristics changed markedly from leaf expansion (late May) through senescence (mid–late October). The photosynthetic capacity of B. ermanii leaves rapidly increased during leaf expansion and decreased during senescence, while that of Q. crispula leaves changed gradually. The relationships among LMA, photosynthetic capacity, and nitrogen content changed throughout the season. The timings (calendar dates) of leaf expansion, maturity, and senescence differed among the 7 years, indicating that interannual variations in micrometeorological conditions strongly affected leaf phenological events. We examined the seasonal changes as a function of the date or cumulative air temperatures. From leaf expansion to maturity, the increases in chlorophyll content, A max, V cmax, J max, and LMA were explained well by the growing-degree days, and their decreases in autumn were explained well by chilling-degree days. Our findings will be useful for predicting the effects of current variations in climatic conditions and future climate change on forest canopy structure and function.Ecological Research 12/2014; 30(2). DOI:10.1007/s11284-014-1222-6 · 1.51 Impact Factor
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ABSTRACT: Aboveground production in terrestrial plant communities is commonly expressed in amount of carbon, or biomass, per unit surface. Alternatively, expressing production per unit volume allows the comparison of communities by their fundamental capacities in packing carbon. In this work we reanalyzed published data from more than 900 plant communities across nine ecosystems to show that standing dry biomass per unit volume (biomass packing) consistently averages around 1 kg/m(3) and rarely exceeds 5 kg/m(3) across ecosystem types. Furthermore, we examined how empirical relationships between aboveground production and plant species richness are modified when standing biomass is expressed per unit volume rather than surface. We propose that biomass packing emphasizes species coexistence mechanisms and may be an indicator of resource use efficiency in plant communities.01/2015; 3:e849. DOI:10.7717/peerj.849