Skunk River Review Fall 1995, Vol 7

https://openspace.dmacc.edu/skunkriver/1016/thumbnail.jp

Forty-Two Years of Succession Following Strip Clearcutting in a Northern Hardwoods Forest in Northwestern Massachusetts

We investigated the effects of strip width, slope position, and soil scarification in a split–split plot design on the regeneration of northern hardwoods in northwestern Massachusetts. Whole plots of 20 and 40 m in width were cut in 1954 in a second growth forest dominated by Betula papyrifera. Slope position and soil scarification were the split and split–split plot treatments, respectively. We measured height for all tree species present in randomly located 4 m2 plots beginning in 1955 and at irregular intervals over the following 42-year period. We measured all trees in the cut strips in 1996. Prunus pensylvanica was the dominant species initially, but had nearly disappeared from the cut strips by 1996. Soil scarification significantly increased initial establishment of B. papyrifera, but density and basal area of this species did not differ by soil treatment in 1996. Tree composition in cut strips was weakly correlated with soil moisture, soil scarification, and initial tree density immediately following cutting, but high spatial variation in species composition and low replication made it difficult to detect any significant correlations among the distribution and abundance of different species and selected environmental variables. The canopy of the cut strips is even-aged; establishment of most canopy trees occurred within 5 years following cutting. A comparison of successional trends in adjacent uncut strips with the trends in the cut strips indicates that cutting has altered the sequence of successional changes in forest composition increasing the abundance of some species that were of low importance prior to cutting. In 1996, Acer rubrum and A. saccharum are replacing B. papyrifera in the canopy of the uncut strips. The canopy of the cut strips consists of a diverse and spatially varying mixture of intermediate hardwoods including Quercus rubra, Fraxinus americana, Betula lenta, Acer rubrum,B. papyrifera, and an understory of late successional hardwoods

Forty-Two Years of Succession Following Strip Clearcutting in a Northern Hardwoods Forest in Northwestern Massachusetts

We investigated the effects of strip width, slope position, and soil scarification in a split–split plot design on the regeneration of northern hardwoods in northwestern Massachusetts. Whole plots of 20 and 40 m in width were cut in 1954 in a second growth forest dominated by Betula papyrifera. Slope position and soil scarification were the split and split–split plot treatments, respectively. We measured height for all tree species present in randomly located 4 m2 plots beginning in 1955 and at irregular intervals over the following 42-year period. We measured all trees in the cut strips in 1996. Prunus pensylvanica was the dominant species initially, but had nearly disappeared from the cut strips by 1996. Soil scarification significantly increased initial establishment of B. papyrifera, but density and basal area of this species did not differ by soil treatment in 1996. Tree composition in cut strips was weakly correlated with soil moisture, soil scarification, and initial tree density immediately following cutting, but high spatial variation in species composition and low replication made it difficult to detect any significant correlations among the distribution and abundance of different species and selected environmental variables. The canopy of the cut strips is even-aged; establishment of most canopy trees occurred within 5 years following cutting. A comparison of successional trends in adjacent uncut strips with the trends in the cut strips indicates that cutting has altered the sequence of successional changes in forest composition increasing the abundance of some species that were of low importance prior to cutting. In 1996, Acer rubrum and A. saccharum are replacing B. papyrifera in the canopy of the uncut strips. The canopy of the cut strips consists of a diverse and spatially varying mixture of intermediate hardwoods including Quercus rubra, Fraxinus americana, Betula lenta, Acer rubrum,B. papyrifera, and an understory of late successional hardwoods

Membrane trafficking and mitochondrial abnormalities precede subunit c deposition in a cerebellar cell model of juvenile neuronal ceroid lipofuscinosis

<p>Abstract</p> <p>Background</p> <p>JNCL is a recessively inherited, childhood-onset neurodegenerative disease most-commonly caused by a ~1 kb <it>CLN3 </it>mutation. The resulting loss of battenin activity leads to deposition of mitochondrial ATP synthase, subunit c and a specific loss of CNS neurons. We previously generated <it>Cln3</it>^Δex7/8knock-in mice, which replicate the common JNCL mutation, express mutant battenin and display JNCL-like pathology.</p> <p>Results</p> <p>To elucidate the consequences of the common JNCL mutation in neuronal cells, we used P4 knock-in mouse cerebella to establish conditionally immortalized Cb<it>Cln3 </it>wild-type, heterozygous, and homozygous neuronal precursor cell lines, which can be differentiated into MAP-2 and NeuN-positive, neuron-like cells. Homozygous Cb<it>Cln3</it>^Δex7/8precursor cells express low levels of mutant battenin and, when aged at confluency, accumulate ATPase subunit c. Recessive phenotypes are also observed at sub-confluent growth; cathepsin D transport and processing are altered, although enzyme activity is not significantly affected, lysosomal size and distribution are altered, and endocytosis is reduced. In addition, mitochondria are abnormally elongated, cellular ATP levels are decreased, and survival following oxidative stress is reduced.</p> <p>Conclusions</p> <p>These findings reveal that battenin is required for intracellular membrane trafficking and mitochondrial function. Moreover, these deficiencies are likely to be early events in the JNCL disease process and may particularly impact neuronal survival.</p