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Sea-level rise associated with climate change presents a major challenge to plant diversity and ecosystem service provision in coastal wetlands. In this study, we investigate the effect of sea-level rise on benthos, vegetation, and ecosystem diversity in a tidal wetland in west Wales, the UK. Present relationships between plant communities and environmental variables were investigated through 50 plots at which vegetation (species and coverage), hydrological (surface or groundwater depth, conductivity) and soil (matrix chroma, presence or absence of mottles, organic content, particle size) data were collected. Benthic communities were sampled at intervals along a continuum from saline to freshwater. To ascertain future changes to the wetlands' hydrology, a GIS-based empirical model was developed. Using a LiDAR derived land surface, the relative effect of peat accumulation and rising sea levels were modelled over 200 years to determine how frequently portions of the wetland will be inundated by mean sea level, mean high water spring and mean high water neap conditions. The model takes into account changing extents of peat accumulation as hydrological conditions alter. Model results show that changes to the wetland hydrology will initially be slow. However, changes in frequency and extent of inundation reach a tipping point 125 to 175 years from 2010 due to the extremely low slope of the wetland. From then onwards, large portions of the wetland become flooded at every flood tide and saltwater intrusion becomes more common. This will result in a reduction in marsh biodiversity with plant communities switching toward less diverse and occasionally monospecific communities that are more salt tolerant. While the loss of tidal freshwater wetland is in line with global predictions, simulations suggest that in the Teifi marshes the loss will be slow at first, but then rapid. While there will be a decrease in biodiversity, the model indicated that at least for one ecosystem service, carbon storage, there is potential for an increase in the near future.

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Biotic interactions can shape phylogenetic community structure (PCS). However, we do not know how the asymmetric effects of foundation species on communities extend to effects on PCS. We assessed PCS of alpine plant communities around the world, both within cushion plant foundation species and adjacent open ground, and compared the effects of foundation species and climate on alpha (within-microsite), beta (between open and cushion) and gamma (open and cushion combined) PCS. In the open, alpha PCS shifted from highly related to distantly related with increasing potential productivity. However, we found no relationship between gamma PCS and climate, due to divergence in phylogenetic composition between cushion and open sub-communities in severe environments, as demonstrated by increasing phylo-beta diversity. Thus, foundation species functioned as micro-refugia by facilitating less stress-tolerant lineages in severe environments, erasing a global productivity - phylogenetic diversity relationship that would go undetected without accounting for this important biotic interaction.

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In subalpine forests of the northern Rocky Mountains, fire exclusion has contributed to large-scale shifts from early-successional whitebark pine (Pinus albicaulis Engelm.) to late-successional subalpine fir (Abies lasiocarpa (Hook.) Nutt.), a species assumed to be more shade tolerant than whitebark pine and with leaf to sapwood area ratios (A(L):A(S)) over twice as high. Potential consequences of high A(L):A(S) for subalpine fir include reduced light availability and, if hydraulic sufficiency is maintained, increased whole-tree water use. We measured instantaneous gas exchange, carbon isotope ratios and sap flow of whitebark pine and subalpine fir trees of different sizes in the Sapphire Mountains of western Montana to determine: (1) whether species-specific differences in gas exchange are related to their assumed relative shade tolerance and (2) how differences in A(L):A(S) affect leaf- and whole-tree water use. Whitebark pine exhibited higher photosynthetic rates (A = 10.9 micromol x m(-2) x s(-1) +/- 1.1 SE), transpiration rates (E = 3.8 mmol x m(-2) x s(-1) +/- 0.7 SE), stomatal conductance (g(s) = 166.4 mmol x m(-2) x s(-1) +/- 5.3 SE) and carbon isotope ratios (delta13C = -25.5 per thousand +/- 0.2 SE) than subalpine fir (A = 5.7 micromol x m(-2) x s(-1) +/- 0.9 SE; E = 1.4 mmol x m(-2) x s(-1) +/- 0.3 SE; g(s) = 63.4 mmol x m(-2) x s(-1) +/- 1.2 SE, delta13C = -26.2 per thousand +/- 0.2 SE; P < 0.01 in all cases). Because subalpine fir had lower leaf-area-based sap flow than whitebark pine (QL = 0.33 kgx m(-2) x day(-1) +/- 0.03 SE and 0.76 kg x m(-2) x day(-1) +/- 0.06 SE, respectively; P < 0.001), the higher A(L):A(S) in subalpine fir did not result in direct proportional increases in whole-tree water use, although large subalpine firs used more water than large whitebark pines. The linear relationships between tree size and daily water use (r2 = 0.94 and 0.97 for whitebark pine and subalpine fir, respectively) developed at the Sapphire Mountains site were applied to trees of known size classes measured in 12 natural subalpine stands in the Bob Marshall Wilderness Complex (western Montana) ranging from 67 to 458 years old. Results indicated that the potential for subalpine forests to lose water by transpiration increases as succession proceeds and subalpine fir recruits into whitebark pine stands.

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Invading exotic plants are thought to succeed primarily because they have escaped their natural enemies, not because of novel interactions with their new neighbors. However, we find that Centaurea diffusa, a noxious weed in North America, has much stronger negative effects on grass species from North America than on closely related grass species from communities to which Centaurea is native. Centaurea's advantage against North American species appears to be due to differences in the effects of its root exudates and how these root exudates affect competition for resources. Our results may help to explain why some exotic species so successfully invade natural plant communities.

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Current concepts of the role of interspecific interactions in communities have been shaped by a profusion of experimental studies of interspecific competition over the past few decades. Evidence for the importance of positive interactions - facilitations - in community organization and dynamics has accrued to the point where it warrants formal inclusion into community ecology theory, as it has been in evolutionary biology.

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Increases in the concentration of atmospheric carbon dioxide may have a fertilizing effect on plant growth by increasing photosynthetic rates and therefore may offset potential growth decreases caused by the stress associated with higher temperatures and lower precipitation. However, plant growth is determined both by rates of net photosynthesis and by proportional allocation of fixed carbon to autotrophic tissue and heterotrophic tissue. Although CO2 fertilization may enhance growth by increasing leaf-level assimilation rates, reallocation of biomass from leaves to stems and roots in response to higher concentrations of CO2 and higher temperatures may reduce whole-plant assimilation and offset photosynthetic gains. We measured growth parameters, photosynthesis, respiration, and biomass allocation of Pinus ponderosa seedlings grown for 2 months in 2×2 factorial treatments of 350 or 650µ bar CO2 and 10/25° C or 15/30° C night/day temperatures. After 1 month in treatment conditions, total seedling biomass was higher in elevated CO2, and temperature significantly enhanced the positive CO2 effect. However, after 2 months the effect of CO2 on total biomass decreased and relative growth rates did not differ among CO2 and temperature treatments over the 2-month growth period even though photosynthetic rates increased ≈7% in high CO2 treatments and decreased ≈10% in high temperature treatments. Additionally, CO2 enhancement decreased root respiration and high temperatures increased shoot respiration. Based on CO2 exchange rates, CO2 fertilization should have increased relative growth rates (RGR) and high temperatures should have decreased RGR. Higher photosynthetic rates caused by CO2 fertilization appear to have been mitigated during the second month of exposure to treatment conditions by a ≈3% decrease in allocation of biomass to leaves and a ≈9% increase in root:shoot ratio. It was not clear why diminished photosynthetic rates and increased respiration rates at high temperatures did not result in lower RGR. Significant diametrical and potentially compensatory responses of CO2 exchange and biomass allocation and the lack of differences in RGR of ponderosa pine after 2 months of exposure of high CO2 indicate that the effects of CO2 fertilization and temperature on whole-plant growth are determined by complex shifts in biomass allocation and gas exchange that may, for some species, maintain constant growth rates as climate and atmospheric CO2 concentrations change. These complex responses must be considered together to predict plant growth reactions to global atmospheric change, and the potential of forest ecosystems to sequester larger amounts of carbon in the future.

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The frequency of occurrence of various types of dementing disorders has been ascertained primarily from autopsied series. Since autopsy is voluntary, it is unknown if these series are representative of the entire demented population. To assess this issue, all deaths occurring over a 5-year period in our Memory Disorders Clinic were reviewed, and clinical variables and diagnoses were compared between patients who were autopsied and those who were not. Sixty-nine patients died; 43% (n = 30) underwent autopsy, and 57% (n = 39) did not. Race (no black patients were autopsied), age of disease onset, age of presentation to the clinic, age of death, and interval between last clinic contact and death (significantly less for nonautopsied patients) were found to differ between the two groups. However, clinical diagnosis of dementia was similar in the two groups. The clinical diagnosis was confirmed in 84% of autopsied patients. These results suggest that there are no major differences between clinical diagnoses for autopsied and non-autopsied patients and that the frequency of occurrence of various dementias obtained through autopsied series are representative of the demented population.

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In Alzheimer's disease (AD), the relationship between white-matter changes on magnetic resonance images and behavior are unclear. Therefore, magnetic resonance images, cognition, and psychiatric state were assessed in patients with AD with depression (AD/DEP; n = 18) and without depression (AD; n = 45), older depressed patients (n = 12) and older normal individuals (n = 25). High-intensity signals in the cortex and subcortical regions were similar in number and proportions among all groups, even when hypertensive patients were excluded. No correlations to cognitive or psychiatric state were found. Periventricular signals were categorized using a 1- (absent) to 6- (thick, irregular caps and stripes) point scale. The categories were similar among groups except that patients with AD exhibited more category 5 changes than did normal subjects, neuropsychological performance was significantly worse in patients with AD who had category 5 and 6 changes when compared to those in category 1. These results suggest that periventricular changes may predict poor neuropsychological performance in patients with AD. However, neither deep white-matter lesions nor periventricular changes are useful for diagnostic purposes.

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Descriptive and experimental studies of desert shrub distributions have revealed important questions about the mechanisms by which plants interact. For example, do roots interact by mechanisms other than simple competition for limiting resources? We investigated this question using the desert shrubs Ambrosia dumosa and Larrea tridentata grown in chambers that allowed observation of roots during intraplant and intra- and interspecific interplant encounters. Two types of root "communication" were revealed. Ambrosia root systems appear to be capable of detecting and avoiding other Ambrosia root systems, whereas Larrea roots inhibit Larrea and Ambrosia roots in their vicinity.

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Considerable heterogeneity exists in the criteria used for the establishment of stages of impairment for patients with dementia. The valid distinction of stages is important both for clinical interpretation and the study of dementia. This study reports on the use of the Mattis Dementia Rating Scale (DRS) in staging dementia. Using a sample of 42 patients diagnosed with Alzheimer-type dementia, DRS performance and a rating of Instrumental Activities of Daily Living (IADL) were compared with clinical ratings of dementia severity. Total DRS score provides a clinically valid measure of stage of impairment and appeared to provide a better distinction among stages than IADL score. However, use of the IADL score in conjunction with total DRS may improve correspondence with clinical staging over use of the total DRS score alone. Normative data for the DRS are also provided.

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We assessed the effect of chronic long-term physostigmine in 20 patients with probable Alzheimer's disease. Initially, all patients went through a dose-finding phase and a double-blind crossover period, and were subsequently classified as physostigmine responders or nonresponders based on an a priori classification system. We then offered all patients long-term treatment with physostigmine regardless of their initial classification. Results revealed that responders spent significantly (p less than 0.0005) longer time periods on drug (36.1 +/- 4.6 months) than nonresponders (10.8 +/- 3.2). During a 2nd crossover period, 18 months into treatment, responders still demonstrated behavioral improvement, as assessed with the Sandoz Clinical Assessment-Geriatric Scale, whereas there were no behavioral changes observed in nonresponders. There were no effects on formal neuropsychological assessment. The results suggest that a subgroup of Alzheimer's patients benefits from long-term physostigmine therapy.

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To assess the efficacy of oral physostigmine for the treatment of Alzheimer's disease, 20 patients were entered into a clinical trial. All patients underwent a dose-finding phase (two weeks), followed by an open trial (two weeks), and a double-blind crossover phase (two weeks drug, two weeks placebo). Extensive neuropsychological testing (Buschke Selective Reminding procedure, category generation, picture recognition, finger tapping) and measurement of systemic cholinergic parameters were measured during each of these phases. Patients were classified as physostigmine responders and nonresponders based on a priori established criteria. Using these, nine patients were found to respond to physostigmine, while 11 were classified as nonresponders. During baseline conditions, responders when compared to nonresponders were found to have higher concentrations of red blood cell (RBC) choline (Ch) and higher ratios of RBC Ch to plasma Ch. Neuropsychological tests were found to fall into one of three categories. The first group of tests were sensitive to drug effects and differentiated physostigmine responders from nonresponders; the second group was found to predict responsiveness; and the third group was neither predictive nor sensitive to drug effects.

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We describe seven patients with clinical, laboratory, and CT evidence of primary degenerative dementia (Alzheimer's, Pick's). Magnetic resonance imaging demonstrated regions in the white matter consistent with cerebral infarction. MRI may be a sensitive way to differentiate multi-infarct dementia and primary degenerative dementia.

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