Transpiration by trees on land with shallow water-tables: a survey of the literature suggests that transpiration is affected by soil texture

This chapter surveys the literature relating site conditions to wateruse by stands of trees growing above shallow watertables. Analysis of the data suggests that transpiration by stands of trees is affected by Epan, depth of the watertable, planting density and soil texture

Effect of supplemental Ca2+ on NaCl-stressed castor plants (Ricinus communis L.)

Greenhouse experiments were conducted to assess the effects of supplemental Ca2+ in salinised soil on germination and plant growth response of castor plant (Ricinus communis L. Var. Avani-31, Euphorbiaceae). NaCl amounting to 390 g was thoroughly mixed with soil of seven lots, of 100 kg each, to give electrical conductivity of 4.1 dS m–1. Further, Ca(NO3)2 × 4H20 to the quantity of 97.5, 195, 292.5, 390, 487.5, and 585 g was separately mixed with soil of six lots to give 1:0.25, 1:0.50, 1:0.75, 1:1, 1:1.25, and 1:1.50 Na+/Ca2+ ratios, respectively. The soil of the seventh lot contained only NaCl and its Na+/Ca2+ ratio was 1:0. Soil without addition of NaCl and Ca (NO3)2 × 4H20 served as control, with a 0:0 Na+/Ca2+ ratio. Salinity significantly retarded seed germination and plant growth, but the deleterious effects of NaCl on seed germination were ameliorated and plant growth was restored with Ca2+ supply at the critical level (1:0.25 Na+/Ca2+ ratio) to salinised soil. Supply of Ca2+ above the critical level further retarded seed germination and plant growth due to the increased soil salinity. Salt stress reduced N, P, K+ and Ca2+ content in plant tissues, but these nutrients were restored by addition of Ca2+ at the critical level to saline soil. In contrast, Na+ content in plant tissues significantly increased in response to salinity, but significantly decreased with increasing Ca2+ supply to saline soil. The results are discussed in terms of the beneficial effects of Ca2+ supply on the plant growth of Ricinus communis grown under saline conditions

Visual activation of auditory cortex reflects maladaptive plasticity in cochlear implant users

Cross-modal reorganization in the auditory cortex has been reported in deaf individuals. However, it is not well understood whether this compensatory reorganization induced by auditory deprivation recedes once the sensation of hearing is partially restored through a cochlear implant. The current study used electroencephalography source localization to examine cross-modal reorganization in the auditory cortex of post-lingually deafened cochlear implant users. We analysed visual-evoked potentials to parametrically modulated reversing chequerboard images between cochlear implant users (n = 11) and normal-hearing listeners (n = 11). The results revealed smaller P100 amplitudes and reduced visual cortex activation in cochlear implant users compared with normal-hearing listeners. At the P100 latency, cochlear implant users also showed activation in the right auditory cortex, which was inversely related to speech recognition ability with the cochlear implant. These results confirm a visual take-over in the auditory cortex of cochlear implant users. Incomplete reversal of this deafness-induced cortical reorganization might limit clinical benefit from a cochlear implant and help explain the high inter-subject variability in auditory speech comprehension

Does biochar improve establishment of tree seedlings in saline sodic soils?

Reforestation of saline sodic soil is increasingly undertaken as a means of reclaiming otherwise unproductive agricultural land. Currently, restoration of degraded land is limited to species with high tolerances of salinity. Biochar application has the potential to improve physical, biological and chemical properties of these soils to allow establishment of a wider range of plants. In a glasshouse trial, we applied biochar made from Acacia pycnantha (5Mgha-1) or no biochar to either a low (ECe 4·75 dS m-1, ESP 6·9), a moderate (ECe 27·6 dS m-1, ESP 29·3) or a high (ECe 49·4 dS m-1, ESP 45·1) saline sodic soil. The regional common reforestation species Eucalyptus viminalis and Acacia mearnsii were planted as tubestock in to the soils. Early establishment indicators, including growth, plant condition and nutrition, were assessed at the end of a simulated growing season, 108days after biochar application. Application of biochar increased height, and decreased root:shoot and the concentration of Mn, N and S in plants of E.viminalis when grown in the highly saline sodic soil. Biochar application increased the concentration of B in leaves of E.viminalis and increased the concentration of P, K and S in leaves of A.mearnsii when grown in the low saline sodic soil. The results confirm that there is potential for biochar to assist in reforestation of saline sodic soils

Future environmental impacts and vulnerabilities

The focus of this chapter is on climate-change impacts on the environment, the structure and functioning of forests, on their biodiversity, and on the services and goods provided by forests in order to identify key vulnerabilities. Based on the findings of the IPCC Fourth Assessment Report (IPCC 2007d), we first introduce four clusters (unavoidable, stable, growth, and fast growth) of climate change scenarios commonly sed to quantitatively assess climate change impacts (sub-chapter 3.2). At the global scale (sub-chapter 3.3) as well as in the four domains (boreal – sub-chapter 3.4; temperate – 3.5; subtropical – 3.6; tropical – 3.7), our CCIAV-assessment (see glossary) for forests shows that many forests can adapt to a moderate climate change if water is sufficiently available, notably in currently temperature limited areas (unavoidable, lower end stable). In some temperate or boreal regions, certain forests can even increase their primary productivity in a moderate climate change. However, some of these benefits are easily offset as climate warms and the adaptive capacity of currently water limited, fire or insect prone forests is frequently exceeded already by a limited climate change (unavoidable, stable). Many other forests become also vulnerable to an unmitigated climate change (growth, fast growth) as their adaptive capacity is exceeded. Forests currently sequester significant amounts of carbon; a key vulnerability consists in the loss of this service, and forests may even turn into a net source. Among land ecosystems, forests currently house the largest fraction of biodiversity; unmitigated climate change threatens to put significant parts of it at risk. The boreal domain, being especially sensitive, serves as a model case and is treated in particular depth. Finally, conclusions are drawn to summarize all findings on the global as well as regional scale