Deep-rooted Trees Research Articles

Nitrate in groundwater and N circulation in eastern Botswana

Nitrate pollution due to deep leaching from pit latrines has caused water supply wells in eastern Botswana to exceed health limits concerning nitrate. It was deduced from the estimated intake of salt and protein by the population that, as an average, about 10 percent of the human nitrogen excretion is leached to the groundwater. This fraction was also found in southern India, where on-the-ground excretion is customary. The nitrogen circulation in general in the savanna ecosystem is not appreciably affected in spite of a large livestock density. Overall nitrate leaching is in the order of 1.5 kg N/ha/y, similar to that in another semiarid area in southern India. However, in India, there seems to be a more diffuse areal leaching from agriculture as well as from villages. Measures to minimize the nitrate leaching could be to plant deep-rooted trees adjacent to pit latrines or to use latrines that separate the urine from the faces for a more near-surface infiltration facilitating plant uptake. Measures to minimize leaching will also lessen the rick for bacterial pollution of the groundwater.

Mineralization and Uptake of Triazine Pesticide in Soil‐Plant Systems

Deep-rooted trees planted as a buffer zone can intercept runoff and eroded sediments, thus reducing non–point-source pollution due to agricultural chemicals. In this study, \IPopulus\N sp. were grown in bioreactors with an agricultural soil (silt-loam) and in a silica-sand media; both were spiked with ¹\u4C uniformly ring-labeled atrazine. The plants took up over 11% of the ¹\u4C labeled atrazine applied to the silt-loam soil and over 91% of that applied to the silica sand media, with the majority of the ¹\u4C accumulating as non-phytotoxic metabolites in the leaves. Research suggests that, in addition to nutrient uptake, poplar tree buffer strips may be effective in removing atrazine from agricultural percolation and runoff water.

Vegetation-induced, subsurface precipitation of carbonate as an aggradational process in the permanent swamps of the Okavango (delta) fan, Botswana

Islands constitute an important geomorphological component of the permanent swamps of the Okavango alluvial fan. Studies of the topography, soil chemistry, groundwater chemistry and vegetation cover across several islands indicate that many islands form as a result of the subsurface precipitation of calcite and probably amorphous silica, which produces vertical expansion, creating topographic relief. The main agent responsible for this precipitation is transpiration, especially by large, deep-rooted trees, which increases the salinity of the groundwater, leading to saturation in calcite and silica. The process ultimately leads to the development of highly saline groundwater and results in marked zonation of vegetation across the islands. Numerical modelling of the process suggests that salinization of the groundwater beneath an island takes between 100 and 200 yr. High calcite contents in island soils appear to be the product of several cycles of salinization, which are interspersed with periods of swamp abandonment during which the more soluble alkali salts are leached from the islands. Island formation represents an important process in the overall aggradation of the alluvial fan.

Foundation problems in Champlain clays during droughts. II. Case histories

This paper presents the results of a 3 year monitoring program of the volumetric water content in two clay deposits on Montréal Island. The water content was monitored by means of a neutron depth moisture probe, which was lowered down in a series of 3–6 m deep, permanently installed, aluminium access tubes. These tubes are located at various distances from deep-rooted trees on two experimental sites. On the first site, a two-storey reinforced concrete building, surrounded by four rows of 15–20 m high silver maples, has suffered a differential settlement of over 150 mm. On the second site, a three-storey apartment block, surrounded on two sides by a row of 5–10 m high maples, has suffered a differential settlement of about 50 mm. The paper analyses the volumetric water content variations and compares them with both the rainfall deficits calculated for the period of observation and the elevation profiles of the building foundations. In addition, a comparison is made between the observed damages and a classification proposed by the Building Research Establishment of England. Key words : volumetric water content, trees, settlement, distortions, clay deposits, seasonal variations, damages.

The Deep-Rooted Tree Sanjo Collection

The Deep-Rooted Tree Sanjo Collection

Ppuri Kip'un Namu Sanjo Chonjip [The Deep-Rooted Tree Sanjo Collection

Ppuri Kip'un Namu Sanjo Chonjip [The Deep-Rooted Tree Sanjo Collection

The Deep-Rooted Tree Pansori Collection

The Deep-Rooted Tree Pansori Collection

Tropical Highland Agricultural Development in a Monsoonal Climate: The Utilization of imperata Grassland in Northern Thailand

Tropical soils are commonly highly weathered and nutritionally poor, and their apparent fertility derives principally from good organic development and rapid mineralization of the detrital pool. When the forest is cleared the nutritional status declines rapidly and restoration is dependent upon site recapture by successional species. Maintenance of adequate fertility for slash-and-burn utilization depends upon the effectiveness and duration of bush fallow. Commonly, over-utilization has resulted in degradation of fertility to the point where unproductive but relatively stable grassland dominates. Some loss of site nutrient capital occurs but, more importantly, there are significant deleterious changes to the soil organic regime. Improvement and stabilization of degraded soils requires reintroduction of the pattern of nutrient dynamics that is evident in native forests. This is best accomplished by species with the capacity to create the appropriate microclimatic conditions that will allow devel- opment of a rapidly cycling surface organic pool of nutrients. Deep-rooted tree species appear most effective and these should be encouraged as a first priority, either as plantations of selected exotics, or by facilitating natural regrowth. Incorporation of agricultural or pastoral phases into a forest-based system of land use is briefly discussed; it is necessary to avert present land degradation under short-cycle swidden cultivation.

Collection Korea Britannica - The Deep-rooted Tree P'ansori Collection. Tan-ga (11 songs). Pansori: “Chŏkpyŏk-ka,” “Chunhyang-ga,” “Hŭngbo-ga,” “Simch'ŏng-ga,” “Sugung-ga.” Six volumes of comentary by Yi Po-hyŏng; translation in English summary by Bang-song Song. Thirty-one 12“ 33 ½ rpm discs in six boxes cased. Korea Britannica Corporation, Seoul, Korea, a subsidiary of Encyclopaedia Britannica, Inc.

Collection Korea Britannica - The Deep-rooted Tree P'ansori Collection. Tan-ga (11 songs). Pansori: “Chŏkpyŏk-ka,” “Chunhyang-ga,” “Hŭngbo-ga,” “Simch'ŏng-ga,” “Sugung-ga.” Six volumes of comentary by Yi Po-hyŏng; translation in English summary by Bang-song Song. Thirty-one 12“ 33 ½ rpm discs in six boxes cased. Korea Britannica Corporation, Seoul, Korea, a subsidiary of Encyclopaedia Britannica, Inc. - Volume 15

Ecophysiological studies of Sonoran Desert plants : II. Seasonal photosynthesis patterns and primary production of Ambrosia deltoidea and Olneya tesota.

The gas exchange and water relations of two Sonoran Desert plants was measured throughout a 12-month period. Seasonal photosynthesis patterns of both plants followed the seasonal variation in plant water potential. Ambrosia deltoidea, a drought-deciduous shrub, is mainly winter-spring active since maximum photosynthesis rates of 38 mg CO2 dm-2 h-1 were measured at this time. This plant is characterized by marked seasonal variations in plant water potential, and was deciduous for approximately 120 days when plant water potential was below-50 bars. Olneya tesota, a non-riparian microphyllous tree, is evergreen and photosynthetically active throughout the entire year, although demonstrating maximum photosynthesis rates of 12 mg CO2 dm-2 h-1 in spring and summer. The deep-rooted tree species maintains a favorable year-round water balance since minimum plant water potentials were seldom below-33 bars. The two species maintain a relatively high water use efficiency throughout the year, despite the high evaporative gradient characteristic of the Sonoran Desert.The leaves are the major site for carbon assimilation, contributing 87 and 81% of the annual carbon gain for the shrub and tree species, respectively. Above-ground gross primary production throughout the 12-month period was estimated solely from the leaf 14CO2 assimilation studies. This production estimate was compared to above-ground net primary production determined by the harvest method. For both plant species gross production was interpreted to exceed net production by nearly a three-fold difference. On a per plant basis gross production was estimated to be 1.14 and 7.42 kg dry wt plant-1 yr-1 for A. deltoidea and O. tesota. The large difference between net and gross production is probably related to year-round utilization of carbon.

Foundation Clay Shrinkage Caused by Large Trees

Noticable cracking began to develop in brick structures on shallow foundations 20 yr after construction on Selfridge Air Force Base, Mich. During the following 10-yr period, the cracking progressed at an increasing rate until several two-story brick houses became unfit for occupancy. The usual soil mechanics theories could not satisfy the observed nature and time relationship of the foundation settlements. The most serious structural failures occurred where large deep-rooted trees were growing in the proximity of the foundations. Soil exploration data verified that tree transpiration during the growing season extracted ground water resulting in shrinkage of the underlying clay strata. Shallow exterior footings within the subsidence area surrounding large trees suffered settlements differential with respect to other parts of the foundation. Selective tree removal was performed concurrently with the restoration of the damaged houses. During the first year after this remedial action, no additional noticeable differential settlements have occurred.

GEOBOTANICAL INVESTIGATIONS IN PROSPECTING FOR ORE DEPOSITS

The use of plants as indicators in prospecting for minerals is discussed on a broad scale from the standpoints both of available literature and field experiments. The method of isoline mapping of mineral deposits by means of metal content in ashes of plant parts is detailed,. The author cautions against too broad use of any single species as a “direct” indicator or too heavy reliance on ash content, as some species tend to concentrate certain minerals, regardless of soil composition. Instead, a combination of species as indicators and a combination of factors, such as appearance of leaves, luxuriance of the plant, and color and time of blooms is recommended. The tendency of some minerals to nullify the effect of others–iron counteracting the effect of copper, for instance — is noted, as well as different effects on plants of different salts of the same mineral. In spite of these qualifications and the early, stage of development of this technique, the method has particular merit in areas where the strata overlying the metal-bearing deposits is relatively thick. Analyzing the ash content of leaves of deep-rooted trees is particularly helpful in detecting the presence of an ore mineral in such a situation. — A. Eustus