Takeshi Tange

Deer density affects ground-layer vegetation differently in conifer plantations and hardwood forests on the Boso Peninsula, Japan

Deer overabundance reduces forest ground-layer vegetation and can cause cascading impacts on a forest ecosystem. To predict these effects, we must elucidate the relationship between deer density and the status of ground-layer vegetation. This relationship was studied in the Boso Peninsula, where the deer population density exhibits a clear geographical gradient. We examined species richness and cover of ground-layer vegetation at several cedar plantations and hardwood forests in the Boso Peninsula. We also examined whether deer impacts were altered by light condition, soil water content and forest type (cedar and hardwood). Species richness of ground-layer vegetation was maximized at an intermediate level of deer density, suggesting an intermediate disturbance effect. This phenomenon was compatible with the observation that evergreen species, which were competitive dominants, decreased with increasing deer density, whereas less competitive deciduous species increased until herbivory was intermediate. As deer density increased, cover of ground-layer vegetation gradually decreased, but species unpalatable to deer increased in abundance, suggesting indirect positive effects of deer for unpalatable species. Cedar plantations tended to have greater species richness and ground-layer cover than hardwood forests with similar deer levels. Canopy openness, an indicator of light conditions, increased species richness of hardwood forests and ground-layer cover of cedar plantations, even under deer herbivory. Topographic wetness index, an indicator of soil water content, significantly increased the ground-layer cover of cedar plantations under deer herbivory. These results emphasize the importance of environmental productivity and forest type in the management of ground-layer vegetation experiencing deer overabundance.

BAAD: a biomass and allometry database for woody plants

Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259 634 measurements collected in 176 different studies, from 21 084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01–100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub-sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross-section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the worlds vegetation.

Transient Proliferation of Proanthocyanidin-Accumulating Cells on the Epidermal Apex Contributes to Highly Aluminum-Resistant Root Elongation in Camphor Tree

Aluminum (Al) is a harmful element that rapidly inhibits the elongation of plant roots in acidic soils. The release of organic anions explains Al resistance in annual crops, but the mechanisms that are responsible for superior Al resistance in some woody plants remain unclear. We examined cell properties at the surface layer of the root apex in the camphor tree (Cinnamomum camphora) to understand its high Al resistance mechanism. Exposure to 500 μm Al for 8 d, more than 20-fold higher concentration and longer duration than what soybean (Glycine max) can tolerate, only reduced root elongation in the camphor tree to 64% of the control despite the slight induction of citrate release. In addition, Al content in the root apices was maintained at low levels. Histochemical profiling revealed that proanthocyanidin (PA)-accumulating cells were present at the adjacent outer layer of epidermis cells at the root apex, having distinctive zones for cell division and the early phase of cell expansion. Then the PA cells were gradually detached off the root, leaving thin debris behind, and the root surface was replaced with the elongating epidermis cells at the 3- to 4-mm region behind the tip. Al did not affect the proliferation of PA cells or epidermis cells, except for the delay in the start of expansion and the accelerated detachment of the former. In soybean roots, the innermost lateral root cap cells were absent in both PA accumulation and active cell division and failed to protect the epidermal cell expansion at 25 μm Al. These results suggest that transient proliferation and detachment of PA cells may facilitate the expansion of epidermis cells away from Al during root elongation in camphor tree.

Structure, allometry, and biomass of plantation Metasequoia glyptostroboides in Japan

We quantified structural features and the aboveground biomass of the deciduous conifer, Metasequoia glyptostroboides (Hu and Cheng) in six plantations in central Japan. In order to derive biomass estimates we dissected 14 M. glyptostroboides trees into three structural components (stem wood, branch wood and foliage) to develop allometric equations relating the mass of these components and of the whole tree to diameter at breast height (DBH). We found robust relationships at the branch and whole tree level that allow accurate prediction of component and whole tree biomass. Dominant tree height was similar within five older (>40 years) plantations (27‐33 m) and shorter in a 20-year-old plantation (18 m). Average stem diameter varied from 12.8 cm in the youngest stand to greater than 35 cm in the oldest stand. Metasequoia have relatively compact crowns distributed over the top 30% of the tree although the youngest stand had the deepest crown relative to tree height (up to 38%). At the individual tree level in older stands, 87% of the aboveground biomass was allocated to the stem, 9% to branch wood and 4% to foliage. We found little difference in the relative distribution of above ground biomass among the stands with the exception of lower foliage biomass in larger diameter trees. Total aboveground biomass of the older stands varied twofold, ranging from a maximum of 450 Mg ha ! 1 in a 42-year-old stand to a minimum of 196 Mg ha ! 1 in a 48-year-old stand. Total above ground biomass of the 20-year-old stand was 176 Mg ha ! 1 .

Shoots grafted into the upper crowns of tall Japanese cedar ( Cryptomeria japonica D. Don) show foliar gas exchange characteristics similar to those of intact shoots

The lower foliar photosynthetic rates seen in shoots in the upper crowns of tall trees than those in seedlings could be caused by extrinsic factors, such as hydraulic conductance, for shoots or by irreversible intrinsic change in the meristems during tree development. To clarify which is most significant, we compared foliar gas exchange characteristics and water relations among scions of Japanese cedar (Cryptomeria japonica D. Don) grafted into the upper crowns of tall trees, rooted cuttings developed from scions of the same clones, and intact shoots in the upper crowns of the tall trees. Grafted shoots had the same water regime as intact shoots, as confirmed by their similar water potentials at the turgor loss point, which were more negative than those of the rooted cuttings. No significant difference was observed between the grafted and intact shoots in their light-saturated photosynthetic rate (Pmax), stomatal conductance (gs), photosynthetic capacity, carboxylation efficiency, ratio of intercellular to ambient CO2 concentration (Ci/Ca), and carbon isotope composition (δ13C). Compared with the rooted cuttings, the grafted shoots showed significantly lower Pmax, gs, photosynthetic capacity, and carboxylation efficiency (to 49%, 31%, 68%, and 65%, respectively). The Ci/Ca and δ13C indicated significantly stronger instantaneous and long-term stomatal limitation in the grafted shoots than in the rooted cuttings. These indicate that changes in extrinsic factors can reduce foliar photosynthetic rates in shoots in the upper crowns of tall trees as a result of stronger stomatal limitation and reduced photosynthetic activity, without irreversible intrinsic changes in the meristems.

Ectomycorrhizal Association Enhances Al Tolerance by Inducing Citrate Secretion in Pinus densiflora

To investigate the effects of ectomycorrhizal association on the aluminum (Al) tolerance of Pinus densiflora Sieb. & Zucc., seedlings with or without ectomycorrhizal association with the fungus Pisolithus tinctorius (Pers.) Coker & Couch were exposed to 1 mM Al. Association with P. tinctorius alleviated Al-induced inhibition of root elongation and biomass growth in the mycorrhizal seedlings. Secretion of malate and citrate, both low-molecular-weight organic acids that could detoxify Al by the formation of stable complexes, was investigated in P. tinctorius mycelia and in pine roots with and without P. tinctorius association. Citrate secretion from the P. tinctorius mycelia in vitro was stimulated by Al. Citrate secretion from the roots of the ectomycorrhizal seedlings was also stimulated by Al, but was not detected in the non-mycorrhizal seedlings. These results suggest that citrate secreted from the roots of the ectomycorrhizal seedlings was produced in the hyphae of P. tinctorius. Citrate secretion may play a role in enhancing the Al tolerance of host seedlings.

Growth Response of Melaleuca cajuputi to Flooding in a Tropical Peat Swamp

We investigated the growth response ofMelaleuca cajuputi Powell to flooding at 3 sites in a tropical swamp in southern Thailand. The relative growth rate (RGR) in height tended to be higher where the water level was higher. The maximumRGR in height was achieved during the flood period at the 2 sites where water levels were higher than at the other site. The height growth ofM. cajuputi was not reduced by flooding, but enhanced. No decline in growth due to post-anoxic injury was observed after flooding.Melaleuca cajuputi may have mechanisms to tolerate rhizospheric oxygen deficiency and to avoid post-anoxic injury.

A cell-type-specific defect in border cell formation in the Acacia mangium root cap developing an extraordinary sheath of sloughed-off cells

BACKGROUND AND AIMS Root caps release border cells, which play central roles in microbe interaction and root protection against soil stresses. However, the number and connectivity of border cells differ widely among plant species. Better understanding of key border-cell phenotype across species will help define the total function of border cells and associated genes. METHODS The spatio-temporal detachment of border cells in the leguminous tree Acacia mangium was investigated by using light and fluorescent microscopy with fluorescein diacetate, and their number and structural connectivity compared with that in soybean (Glycine max). KEY RESULTS Border-like cells with a sheet structure peeled bilaterally from the lateral root cap of A. mangium. Hydroponic root elongation partially facilitated acropetal peeling of border-like cells, which accumulate as a sheath that covers the 0- to 4-mm tip within 1 week. Although root elongation under friction caused basipetal peeling, lateral root caps were minimally trimmed as compared with hydroponic roots. In the meantime, A. mangium columella caps simultaneously released single border cells with a number similar to those in soybean. CONCLUSIONS These results suggest that cell type-specific inhibitory factors induce a distinct defective phenotype in single border-cell formation in A. mangium lateral root caps.

Structural characteristics of lignin in primitive pteridophytes: Selaginella species

The lignin chemical structures of eight species of the Selaginella family, which are primitive vascular plants, were characterized by alkaline nitrobenzene oxidation, acidolysis, and ozonation. Selaginella involvens, Selaginella tamariscina, and Selaginella remotifolia were collected from the University Forest in Chiba, the University of Tokyo, Japan, and Selaginella biformis, Selaginella pennata, S. involvens, Selaginella chrysorrhizos, and unidentified Selaginella species (Selaginella sp.) were collected from northern Thailand. Lignin of all Selaginella species examined in this study was rich in syringyl nuclei. It was confirmed that a considerable portion of syringyl nuclei of Selaginella lignin formed syringylglycerol-β-aryl ether intermonomer linkages. The major diastereomer of arylglycerol-β-aryl ether intermonomer linkages of Selaginella lignins was the erythro-form exhibiting angiosperm lignin characteristics. In addition, lignins of S. involvens, S. tamariscina, and S. remotifolia collected from the University Forest in Chiba, the University of Tokyo, Japan, were isolated according to Björkman’s procedure, and structural features of the lignins were spectrometrically analyzed. It was confirmed that lignin of Selaginella species, which are primitive pteridophytes, was typical guaiacyl-syringyl type as well as being similar to angiosperm lignin.

Seasonal changes in photosynthesis of young Cryptomeria japonica growing on ridges and foot-slopes

Abstract The influence of environmental factors affected by topography, especially light conditions in winter, on photosynthetic capacity of field-grown young Cryptomeria japonica trees was studied. Trees with a large increment in height growth tended to have current year needles with high photosynthetic capacity in the growing season. The change in the photosynthetic capacity from October to February, corresponding to the change in chlorophyll content, differed between trees planted near a ridge and on a foot-slope. There was a tendency for trees with a greater exposure to sunshine in winter, such as those near a ridge, to have a reduced chlorophyll content in winter. The photosynthetic capacity of 1-year-old needles of sample trees near a ridge did not recover as much as those on a foot-slope, even if the foliar nitrogen content was high. These results imply that the magnitude of winter injury on the photosynthetic apparatus differed according to the topographical conditions and strongly influenced the photosynthetic capacity during the next growing season.