Coordination between water transport capacity,biomass growth,metabolic scaling and species stature in co‐occurring shrub and tree species

The significance of xylem function and metabolic scaling theory begins from the idea that water transport is strongly coupled to growth rate. At the same time, coordination of water transport and growth seemingly should differ between plant functional types. We evaluated the relationships between water transport, growth and species stature in six species of co‐occurring trees and shrubs. Within species, a strong proportionality between plant hydraulic conductance (K), sap flow (Q) and shoot biomass growth (G) was generally supported. Across species, however, trees grew more for a given K or Q than shrubs, indicating greater growth‐based water‐use efficiency (WUE) in trees. Trees also showed slower decline in relative growth rate (RGR) than shrubs, equivalent to a steeper G by mass (M) scaling exponent in trees (0.77–0.98). The K and Q by M scaling exponents were common across all species (0.80, 0.82), suggesting that the steeper G scaling in trees reflects a size‐dependent increase in their growth‐based WUE. The common K and Q by M exponents were statistically consistent with the 0.75 of ideal scaling theory. A model based upon xylem anatomy and branching architecture consistently predicted the observed K by M scaling exponents but only when deviations from ideal symmetric branching were incorporated.     

How can we quantitatively study insects whose larvae live beneath the forest floor? A case study at an experimental long‐term log‐removal site in Japan

This study quantified the numbers and sex ratio of adult Sericania hidana (Coleoptera: Scarabaeidae) in a subalpine forest in 2017. Data from an area littered with coarse woody debris (CWD) created by a typhoon in 1959 were compared with those from an area where CWD had been cleared by salvage logging. Three types of traps were used: flight interception traps (FITs) with a black light, pitfall traps (PITs), and soil emergence traps (SETs). Carbon and nitrogen stable isotopes were analyzed to evaluate S. hidana diets and habitats. Overall, there were more S. hidana in the unsalvaged sites than in the salvaged sites. The FITs captured only males but SETs captured both males and females. The SETs on CWD captured more S. hidana than did SETs on soil in both the salvaged and unsalvaged sites. The PITs captured only a few individuals; thus, PITs are not suitable for studying this insect, although such traps were previously reported to capture S. hidana adults. Stable isotope analyses suggested that S. hidana feeds on a variety of plant materials, including living plants and CWD. These results suggest that CWD has long‐term effects on insect populations. Soil emergence traps provide an effective method to quantitatively evaluate insect ecology, and FITs can effectively screen for the existence of insects.     

Early Carboniferous plants of the Arkhangelsk Region,Russia

Eight species of fossil plants are described for the first time from the Lower Carboniferous of the Arkhangelsk Region. One of these species, Adiantites lisitzynii O. Orlova et Jurina, is new. The taxonomic composition of the assemblage of 20 species indicates a woody vegetation of the Euramerian aspect. The rich assemblage recovered for the first time from terrigenous deposits of the Arkhangelsk Region dates them to the Visean (Early Carboniferous).     

Wood Decomposition Following a Perennial Lupine Die-Off: A 3-Year Litterbag Study

Woody debris is a conspicuous feature of many ecosystems and can be a large pool of stored carbon and nutrients. In the California coastal prairie, yellow bush lupines (Lupinus arboreus) experience mass die-offs, producing large quantities of woody detritus. Live lupines are fed upon by the stem-boring caterpillars of the ghost moth, Hepialus californicus, and outbreaks of ghost moths are one factor contributing to lupine die-offs. A common detritivore, the terrestrial isopod Porcellio scaber, frequently inhabits ghost moth tunnels in lupine wood. We used a litterbag experiment to test the hypothesis that H. californicus increases decomposition of woody lupine detritus by facilitating its use by P. scaber. Isopod access to wood was crossed with simulated ghost moth boring to measure the independent and interactive effects of these two arthropods on total mass loss, as well as on carbon, nitrogen, and lignin dynamics. Isopods initially colonized litterbags but were not more abundant on L. arboreus logs that had simulated ghost moth boring than on logs without boring. They were rare in litterbags collected at 12 months or later and had no effect on wood decomposition. Simulated ghost moth boring increased wood decomposition (P = 0.0021), from 50.5 to 55.1% mass loss after 3 years. This effect was likely due to increased surface area for microbial utilization of the wood. Lupine wood had an initial lignin content of 14.70 ± 0.67%, but lignin did not appear to decompose during the 3 years of this study, and by the end of the experiment accounted for 32.6 ± 1.12% of the remaining wood. Neither ghost moth boring nor isopod access affected lignin loss. Lupine wood from a die-off in 2002 was estimated to have contained three times more nitrogen per unit area than the yearly input of annual grass litter. The slow decomposition of lupine wood, however, restricts the rate at which nitrogen is released into the soil and results in the storage of carbon and nutrients in lupine wood for several years following such die-offs.     

Prescribed burning reduces species richness of wood-decay fungi in the forests of northwest Arkansas

The present study, which was carried out at three localities in the Ozark Mountains of northwest Arkansas, investigated the effects of prescribed burning on wood-decomposing fungi using samples of decaying woody debris (DWD) placed in plastic incubation chambers. One of the localities had not been subjected to recent prescribed burning, whereas the other localities contained both an unburned area as well as an area recently subjected to burning. In all three localities, small pieces of decaying woody debris (DWD) were collected, placed in the incubation chambers and the latter kept moist for any extended period of time. Pieces of DWD collected in the areas subjected to burning typically displayed evidence of considerable charring. Fruiting bodies appearing in the incubation chambers were removed and identified by sequencing of ribosomal DNA region. A total of 101 specimens representing 80 different taxa were recorded in the entire investigation, but the numbers of both specimens and taxa were appreciably higher for the unburned collecting sites. As such, the data obtained indicate that prescribed burning lowers the species richness of the wood-decomposing fungi associated with DWD at a particular locality. The unique aspect of the present study was the use of incubation chambers to characterize the taxa of fungi associated with CWD.     

Anthropogenic change in subtropical dry forest during a century of settlement in Jaiquí Picado, Santiago Province, Dominican Republic

Aim The dry forests of the tropics have received little scholarly attention relative to their significance and their rate of disappearance. This study aimed to characterize the structure and composition of two intermingled Antillean subtropical dry forest types and shed light upon their origins, development, and possible future conditions. Location Jaiquí Picado, Santiago Province, Dominican Republic (19° 26′ N, 70° 54′ W). Methods Biophysical data from quadrat sampling of vegetation, soils, and site characteristics were subjected to cluster analysis, means comparisons, discriminant analysis, and linear regression. Extensive interviews with local land users provided information on early forests as well as present and historical land use practices. Results Spatial patterning of the area's two main forest types relates closely to past land use but not to any observed differences in the physical characteristics of their sites. ‘Old-growth’ stands found on land never placed in cultivation resemble the forests encountered by late-nineteenth-century settlers of the area in their wealth of woody plant taxa and relative abundance of endemic and other native species. In the ‘scrub’ stands growing on land abandoned from grazing, fully 70% of stems belong to one native (Acacia macracantha Willd.) and two exotic (Haematoxylon campechianum L. and Prosopis juliflora (Sw.) DC.) woody legumes that contribute to the markedly greater representation of deciduous and thorn-bearing individuals in this type. The two forest types do not differ significantly in average bole dimensions, but the canopies of scrub stands are concentrated in a narrower layer, their understories are more open, and they contain more multiple stems of apparent sprout origin. A chronosequence of scrub stands covering a range in age of three decades indicates a moderate increment in species diversity over time and gradual disappearance of some of the more abundant invasive shrubs; but such stands continue to be dominated throughout this period by the same three scrub trees, while most species characteristic of old-growth forests, including many of the least abundant, fail to appear among the regeneration in their understories. Main conclusions Antillean forests classified as thorn scrub may include a form of ‘disclimax’ created through past land use activities in areas once bearing more diverse tropical dry forest. Whether they will ever develop into stands similar to the previous forests is uncertain, given the present state of fragmentation and other processes taking place within these ecosystems.