Species concepts and the definition of a species are discussed in the context of sustainable forest management and the sustainability of biological systems in general. Sustainable forestry requires that the habitats created by silvicultural manipulation match the ecological niches of the species being managed, enabling them not only to grow but to reproduce themselves so they can persist on the landscape beyond the current rotation. For this to be possible, foresters must be able to identify species and understand how species are defined.

Disturbances in forests can kill mature trees, but also create the conditions necessary for the establishment of new tree cohorts and create micro-habitats for new plant and animal species, thereby increasing the species diversity compared to undisturbed stands. We review the types and intensities of disturbances on forests in three regions of the temperate zone of the northern hemisphere: northeastern North America, Central Europe, and East Asia. We focus on (1) the ways in which disturbances affect forest stand development; (2) the differences among the three areas in this regard; (3) the consequences for future forest management. In both northeastern North America and East Asia, hurricanes and typhoons represent the major mode of natural disturbance, while in Central Europe winter windstorms occur after deciduous trees have lost their leaves. Tornadoes can have even greater destructive power (but affect relatively narrow strips of land), and the more severe of these mainly occur in North America. The general disturbance patch system therefore is relatively large in northeastern North America, small in Central Europe, and of intermediate size in temperate East Asia. In addition to wholly natural disturbance factors, human commerce and globalization have enabled new disturbance types by introducing pests and diseases from one region to another. In North America especially, several of the most important foundation species in temperate forests are strongly affected, so that not just the species composition but also the whole forest structure is changing fundamentally. In all three areas in the past the change in land use by growing human populations strongly affected the structure as well as the species composition of forests. Nearly all the recent forest stands of the temperate zone had been used in the past in a particular way, and many of today’s forests had previously been converted into agricultural land. Finally climate change is superimposing itself on forest development worldwide. Nevertheless, climate change is not a new phenomenon, so forest ecosystems in all time periods have been exposed to changing climatic conditions and have had to adapt. Each forest stand therefore represents a unique recent expression of the interaction of environmental conditions and plant species, a “snapshot” of the relevant abiotic and biotic factors, including human impact.

(2009). The Problem of Eastern White Pine (Pinus strobus L.) in Southern New England: Ecophysiology, Site Restriction, and Historical Land-Use Change. Journal of Sustainable Forestry: Vol. 28, Trees and Forests in Space and Time: A Festschrift for Graeme P. Berlyn, pp. 108-131.

We conducted a progressive-drought greenhouse experiment, using potted paper birch (Betula papyrifera) seedlings in their third year of growth, to investigate whether a commercially available organic biostimulant improved plant health and stress tolerance, and to compare four noninvasive, instrument-based methods for monitoring plant stress. In the well-watered (no drought) plants, the biostimulant application significantly increased foliar nitrogen concentrations (P = 0.01) and led to marginally higher rates of photosynthesis (P = 0.10) and slightly higher Fv/Fm fluorescence ratios (P = 0.14). Reflectance indices further indicated that the biostimulant application resulted in increased chlorophyll content (Chl NDI, P = 0.07) and either (depending on interpretation) a significantly higher Chl:carotenoid ratio or a lower proportion of xanthophyll cycle pigments in the de-epoxidated state (PRI, P = 0.02). The PRI results suggest less oxidative stress in the treated plants, which may be related to the fact that the biostimulant used (Roots 3) contained ascorbate, an antioxidant. In the plants exposed to progressive drought, the biostimulant application had similar effects but did not appear to dramatically improve the drought stress tolerance of seedlings, in that impaired physiology occurred at about the same level of soil moisture in both treated and untreated seedlings. Photosynthesis responded to the drought treatment at about 12% to 15% soil moisture content (SMC), whereas PRI did not respond until about 9% to 10% SMC, and Fv/Fm did not respond until about 4% to 5% SMC. Chl NDI did not show a significant response to SMC.

During infection, bacteriophage T4 regulates three sets of genes: early, middle, and late. The host RNA polymerase is capable of transcribing early genes, but middle transcription requires the T4-encoded transcriptional activator, MotA protein, and the T4 co-activator, AsiA protein, both of which bind to the sigma 70 (sigma70) subunit of RNA polymerase. MotA also binds a DNA sequence (a MotA box), centered at position -30. The identification of more than 20 middle promoters suggested that a strong match to the MotA box consensus sequence (t/a)(t/a)TGCTT(t/c)A was critical for MotA activation. We have investigated how specific base changes within the MotA box sequence affect MotA binding and activation in vitro, and we have identified seven new middle promoters in vivo. We find that an excellent match to the sigma70 -10 consensus sequence, rather than an excellent match to the MotA box consensus sequence, is an invariant feature of MotA-dependent promoters. Many single base changes in the MotA box are tolerated in binding and activation assays, indicating that there is more flexibility in the sequence requirements for MotA than was previously appreciated. We also find that using the natural T4 DNA, which contains glucosylated, 5-hydoxymethylated cytosine residues, affects the ability of particular MotA box sequences to activate transcription. We suggest that MotA and AsiA may function like certain eukaryotic TAFs (TATA binding protein (TBP) associated factors) whose binding to TBP results in transcription from new core promoter sequences.

During infection, the bacteriophage T4 transcriptional activator MotA, the co-activator AsiA, and host RNA polymerase are needed to transcribe from T4 middle promoters. Middle promoters contain a -10 region recognized by the sigma(70)subunit of RNA polymerase and a MotA box centered at -30 that is bound by MotA. We have investigated how the loss or modification of base determinants within the MotA box sequence 5'TTTGCTTTA3' (positions -34 to -26 of a middle promoter) affects MotA function. Gel retardation assays with mutant MotA boxes are consistent with the idea that MotA uses minor groove contacts upstream and major groove contacts downstream of the center GC, and does not require any specific base feature at the C.G base-pair at position -30. In particular, the 5-methyl residue on the thymine residue at position -29, a major groove contact, contributes to MotA binding, while converting the T.A at -32 to a C. I base-pair, a change that affects the major but nor the minor groove, yields a MotA box that is similar to wild-type. However, methylation interference analyses indicate that neither the binding of MotA nor the binding of polymerase/MotA/AsiA to the middle promoter PuvsXis inhibited by premethylation of guanine and adenine residues, suggesting that binding does not require minor groove contact with any specific T.A base-pair. Using gel retardation analyses, we calculate an apparent dissociation constant of 130 nM for MotA binding to the wild-type MotA box. Previous work has shown that the N-terminal region of MotA is needed for an interaction between MotA and sigma(70). We suggest that this MotA-sigma(70)interaction helps to stabilize the relatively weak interaction of MotA with the -30 region of middle promoter DNA.

We have developed an efficient PCR-based system that uses RAPD markers for the certification of F1 hybrids of canola. These markers were selected by screening five parental lines used in three crosses X, Y and Z with 131, 131 and 322 primers respectively. Stable DNA fragments that were homozygous and specific to the male inbreds were used to certify F1 hybrid populations. The hybrid production system was based on self-incompatibility (SI) alleles that prevent self-pollination of the female parent. The efficiency of two S-alleles was compared under both field and greenhouse conditions. The percentage of hybridity was estimated in different F1 populations. We found a significant difference between the two alleles for their efficiency in controlling selfing; both alleles were stable under greenhouse conditions, one allele appeared less reliable under field conditions.

We have developed an efficient PCR-based system that uses RAPD markers for the certification of F hybrids of canola. These markers were selected by screening five parental lines used in three crosses X, Y and Z with 131, 131 and 322 primers respectively. Stable DNA fragments that were homozygous and specific to the male inbreds were used to certify F hybrid populations. The hybrid production system was based on self-incompatibility (SI) alleles that prevent self-pollination of the female parent. The efficiency of two S-alleles was compared under both field and greenhouse conditions. The percentage of hybridity was estimated in different F populations. We found a significant difference between the two alleles for their efficiency in controlling selfing; both alleles were stable under greenhouse conditions, one allele appeared less reliable under field conditions.

AbstractDie Reaktion der Biphthalide (I) mit den Hydrazinen (II) führt zu den Phthalidyl‐phthalazinonen (III), von denen einige Reaktionen wie z.B. die Mannich‐Kondensation zu (VI) beschrieben werden.

Weinstein, Mandel M.D.; Roberts, Morton M.D.; Reynolds, Brun M.D.; Marshall, Philip M.D. Author Information