@article {51671, title = {The effect of water and nitrogen amendments on photosynthesis, leaf demography, and resource-use efficiency in Larrea tridentata, a desert evergreen shrub}, journal = {Oecologia}, volume = {80}, year = {1989}, month = {1989}, pages = {341-348}, abstract = {

In the Chihuahuan Desert of southern New Mexico, both water and nitrogen limit the primary productivity of Larrea tridentata, a xerophytic avergreen shrub. Net photosynthesis was positively correlated to leaf N, but only in plants that received supplemental water. Nutrient-use efficiency, defined as photosynthetic carbon gain per unit N invested in leaf tissue, declined with increasing leaf N. However, water-use efficiency, defined as the ratio of photosynthesis to transpiration, increased with increasing leaf N, and thus these two measure of resource-use efficiency were inversely correlated Resorption efficiency was not significantly altered over the nutrient gradient, nor was it affected by irriation treatments. Leaf longevity decreased significantly with fertilization although the absolute magnitude of this decrease was fairly small, in part due to a large background of insect-induced mortality. Age-specific gas exchange measurements support the hypothesis that leaf aging represents a redistribution of resources, rather than actual deterioration or declining resoruce-use efficiency.

}, keywords = {Larrea tridentata, leaf demography, nutrient resportion, nutrient-use efficiency, photosynthesis, water-use efficiency}, doi = {doi:10.1007/BF00379035}, url = {/files/bibliography/350.pdf}, author = {Kate Lajtha and Walter G. Whitford} } @article {51731, title = {The biogeochemistry of phosphorous cycling and phosphorous availability along a desert soil chronosequence}, journal = {Ecology}, volume = {69}, number = {1}, year = {1988}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1988}, pages = {24-39}, abstract = {

The biogeochemistry of the weathering, landscape movements, and chemical transformations of phosphorus and its availability to plants were examined in a chronosequence of soils developed from quartz monzonite alluvium in southern New Mexico. Total P in the soil profile decreased with increasing soil age and was removed from the ecosystem as readily as the most easily leachable bas cations. Although Ca-bound forms of P decreased with increasing soil age, Ca-P remained the single largest fraction of total P in all soils. In contrast, Fe- and Al-bound P was a very small percent of total P in all soils. There was little evidence for the stabilization of P by soil organic matter within this ecosystem; both soil organic P and microbial P represented very small pools of total soil P. Phosphorus availability, measured by in situ resin bags, was not well correlated with soil age or total soil P, and P concentrations in shrub tissues did not reflect changes in forms or total amounts of soil P. The biogeochemical cycle of P in this system differs sharply from that in a more mesic, forested system, where fixation by iron and aluminum oxides and biological activity play more dominant roles in the conservation of P within the ecosystem.

}, keywords = {article, articles, biogeochemistry, calcium carbonate, journal, journals, nutrient cycling, phosphorous cycling, soil, chronosequence, soil, phosphorous, soil, SEE biogeochemistry, weathering}, doi = {10.2307/1943157 }, url = {files/bibliography/JRN00085.pdf}, author = {Kate Lajtha and W. H. Schlesinger} } @article {51730, title = {The effect of CaCO3 on the uptake of phosphorous by two desert shrub species Larrea tridentata (D. C.) Cov. and Parthenium incanum H.B.K.}, journal = {Botany Gazette}, volume = {149}, number = {3}, year = {1988}, note = {//NMSU//NONE, LTER//}, month = {1988}, pages = {328-334}, abstract = {In a phytotron growth study, the effects of soil CaCO3 on the uptake of P by two desert shrub species were species specific. Larrea tridentata seedlings responded to soil CaCO3 with increased root:shoot ratios, increased N:P ratios in tissues, and decreased specific absorption rates of P, indicating that CaCO3 directly inhibited the uptake or the availability of P to roots. Parthenium incanum seedlings responded negatively to CaCO3, but this response was not specific to P uptake and did not appear to be caused by a reduction in P availability. Pedogenic carbonates, present in many arid-land soils of the world, might greatly affect both P availability and the biogeochemical cycle of P in desert ecosystems.}, keywords = {article, articles, calcium carbonate, germination, Larrea, journal, journals, Larrea, phosphorous, nutrient cycling, phosphorous, Larrea, Parthenium, phosphorous, phosphorous, seed, also SEE germination}, author = {Kate Lajtha and W. H. Schlesinger} } @article {51727, title = {The effect of varying nitrogen and phosphorus availability on nutrient use by Larrea tridentata, a desert evergreen shrub}, journal = {Oecologia}, volume = {75}, year = {1988}, note = {//NMSU//NONE, LTER//}, month = {1988}, pages = {348-353}, abstract = {In a phytotron study of the effects of nitrogen and phosphorus supply ration on nutrient uptake and use by Larrea tridentata, seedlings responded to increases in N and P availability with increases in leaf size, total biomass, and leaf nutrient concentration, and with decreases in root:shoot ratio. N and P use efficiency decreased with increasing N and P availability, respectively, but increased with increasing availability of the other nutrient, suggesting that Larrea responds both to the absolute and to the relative availability of limiting nutrients. Absolute amounts of N and P resorption, as well as N and P resorption efficiencies did not demonstrate a significant trend with nutrient availability, and there was no evidence of significant interactions between the two nutrients. More studies of the effects of nutrient interactions in the cycling and use of nutrients by different plant species are needed before more general conclusions can be drawn.}, keywords = {article, articles, journal, journals, Larrea, germination, nitrogen, Larrea, germination, phosphorus, Larrea, nutrients, nitrogen, Larrea, nutrient resorption efficiency, nutrient use efficiency, phosphorus, Larrea, seed, germination}, author = {Kate Lajtha and Klein, Melanie} } @article {51728, title = {Factors affecting phosphate sorption and phosphate retention in a desert ecosystem}, journal = {Soil Science}, volume = {146}, number = {3}, year = {1988}, note = {//NMSU//LTER I//}, month = {1988}, pages = {160-167}, abstract = {

In a study of soils from a chronosequence in southern New Mexico, where CaCO3 accumulation is primarily derived from aeolian input, P adsorption was greatest in the most highly calcic horizons and least in horizons of clay and oxyhydroxide accumulation. Similarly, adsorption capacity was most highly correlated with CaCO3 content. Iron and Al oxyhydroxide contents increased with increasing soil age, and absolute levels were as high as in calcareous soils developed in more humid conditions. Calcium carbonate appears to be the primary geochemical agent capable of the fixation and retention of P within the soil profile in this ecosystem.

}, keywords = {article, articles, biogeochemistry, calcium carbonate, chronosequence, journal, journals, phosphate retention, phosphate sorption, phosphorous, soil, also SEE , soil, aluminim hydrous oxides, soil, chronosequence, soil, iron hydrous oxides}, url = {files/bibliography/JRN00079.pdf}, author = {Kate Lajtha and Bloomer, Sherman H.} } @article {51729, title = {The use of ion-exchange resin bags for measuring nutrient availability in an arid ecosystem}, journal = {Plant and Soil}, volume = {105}, year = {1988}, note = {//NMSU//LTER I//}, month = {1988}, pages = {105-111}, abstract = {

An in situ resin bag technique was used to measure the relative availabilities of N and P along a chronosequence of soils in southern New Mexico, and was compared to two more common indices of nutrient availability. Accumulations of N and P during 10-week intervals over and 18 month period were separable into wet season (September-January) and dry season (February-August) groups, with wet season values significantly greater than dry season values. Only accumulations during the wet season showed significant differences among sites, thus stressing the role of field water regime in interpreting resin accumulation results. Although accumulation patterns of N and P were similar to patterns of \%N and \%P in shrub species growing along the chronosequence, these similarities were not statistically significant. A laboratory experiment demonstrated that bicarbonate-form anion resins are preferable to hydroxyl-form resins, as long as standards are made from solutions extracted by resins to account for variable ion recovery efficiencies.

}, keywords = {article, articles, chronosequence, journal, journals, mineralization, nitrogen, nutrient availability, phosphorus, soil, chronosequence, technique, ion exchange resin bag}, doi = {10.1007/BF02371147 }, url = {files/bibliography/JRN00087.pdf}, author = {Kate Lajtha} } @article {51780, title = {Nutrient reabsorption efficiency and the response to phosphorus fertilization in the desert shrub Larrea tridentata}, journal = {Biogeochemistry}, volume = {4}, year = {1987}, note = {//NMSU//LTER II//}, month = {1987}, pages = {265-276}, abstract = {A field fertilization experiment demonstrated that growth of Larrea tridentata was not limited by phosphorus, even though soils contained high levels of pedogenic carbonates that can potentially fix high amounts of phosphorus. Nutrient reabsorption efficiencies in unfertilized shrubs ranges from 72-86\% for P, making nutrient reabsorption a very effective nutrient conservation mechanism. Absolute amounts of N and P reabsorption increased with N and P concentrations in leaves, with reabsorption being greater during drought stress than during rapid leaf growth. However, only N reabsorption efficiency increased with increasing plant N status. A model was developed to explain patterns of nutrient reabsorption efficiencies over large gradients in nutrient availability.}, keywords = {article, articles, ecosystem, fertilization, phosphorous amendments, journal, journals, Larrea,nutrient use, Larrea,phosphorous, nutrient reabsorption efficiency, nutrient use, phosphorous cycling}, author = {Kate Lajtha} } @article {51781, title = {Phosphorous and pH tolerances in the germination of the desert shrub Larrea tridentata (Zygophyllaceae)}, journal = {Madro{\~n}o}, volume = {34}, number = {1}, year = {1987}, note = {//NMSU//NONE, LTER//}, month = {1987}, pages = {63-68}, abstract = {Seeds of Larrea tridentata, a dominant shrub of deserts in the southwestern U.S., were germinated on both a pH and phosphorus (P) gradient to determine if requirements for germination can help explain the field distribution of Larrea. Germination decreased significantly above pH 8, which is consistent with the conspicuous absence of Larrea from high pH sodic or saline desert soils. Although Larrea tends to be absent from noncalcareous soil, seed germination was not inhibited in acidic solutions. Germination showed no response to P or to interactions of pH and P. In contrast, recent literature has suggested that Larrea may be restricted to calcareous soils of low phosphorus availability due to toxicity of high concentrations of P to seedlings.}, keywords = {article, articles, germination, Larrea, journal, journals, Larrea, germination, phosphorous, Larrea, germination, soil pH, pH tolerances, Larrea, phosphorous, seed, germination}, author = {Kate Lajtha and Weishampel, John and W. H. Schlesinger} } @mastersthesis {51838, title = {The biogeochemistry of phosphorous cycling and phosphorous availability in a desert ecosystem}, year = {1986}, note = {//NMSU//LTER I//}, month = {1986}, school = {Duke University}, type = {Ph.D. Dissertation}, address = {Durham, North Carolina}, abstract = {The geochemistry of the weathering, landscape movement, chemical transformations, and the plant availability of phosphorus was examined in a chronosequence of soils developed from quartz monzonite alluvium in southern New Mexico. All soils contained pedogenic carbonates in upper horizons with caliche layers at depth. Total P in the soil profile decreased with increasing soil age, and was removed from the ecosystem as readily as the most easily leachable base cations. Although Ca-bound forms of P decreased with increasing soil age, Ca-P remained the single largest fraction of total P in all soils.}, keywords = {biogeochemistry, calcium carbonate, chronosequence, dissertation, dissertations, Larrea, calcium carbonate, Larrea, phosphorous, Parthenium, calcium carbonate, Parthenium, phosphorous, phosphorous cycling, seedling response, calcium carbonate, theses, thesis}, author = {Kate Lajtha} } @article {51837, title = {Plant response to variations in nitrogen availability in a desert shrubland community}, journal = {Biogeochemistry}, volume = {2}, year = {1986}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1986}, pages = {29-37}, abstract = {

Spatial variations in nitrogen availability were studied in a desert community codominated by Larrea tridentata (DC.) Cov. and Prosopis glandulosa Torr. Measurements of natural 15N values in tissues suggested that Prosopis obtains approximately half of its nitrogen through direct symbiotic fixation. Soils were collected under 1) Prosopis shrubs, 2) Larrea shrubs \< 2 m from Prosopis (LP), and 3) Larrea\< 2 m from other Larrea but \> 5 m from the nearest Prosopis (LL). Prosopis soils showed significantly higher rates of nitrogen mineralization than LL soils in both A and B horizons. Rates of mineralization in LP soils were significantly higher than rates in LL soils only in the B horizon and were not significantly different from rates in Prosopis soils. Leaf nitrogen concentrations were significantly higher in LP shrubs (2.06\%) than in LL shrubs (1.78\%), although 15N values did not differ between the two shrub types. Nitrogen concentrations in Perezia nana Gray, a perennial herb, were greater in plants under Prosopis shrubs (2.09\%) than under LP shrubs (1.93\%) or LL shrubs (1.67\%). Despite apparent differences in nitrogen availability, biomass of Larrea and density of Perezia did not differ significantly among these sites.

}, keywords = {article, articles, desert shrublands, journal, journals, Larrea,nitrogen, nitrogen availability, nitrogen mineralization, nitrogen stable isotopes, Prosopis,nitrogen}, doi = {10.1007/BF02186963 }, url = {files/bibliography/JRN00038.pdf}, author = {Kate Lajtha and W. H. Schlesinger} }