Effects of Permanent and Temporary Edges on Pinus clausa (sand pine) Architecture and Stand Conditions

Effects of permanent (i.e., maintained) and temporary edges with north- and south-facing exposures were studied in sand pine (Pinus clausa var. clausa) scrub, an open-canopied forest type in Ocala National Forest, Florida. On edges and interiors of four stands of each type, we measured canopy tree architecture in 5 x 100 m plots and stand density and basal area in 5 x 200 m plots. Edge effects were modest but often stronger on south- than north-facing edges and along permanent forest roads than temporary edges of clearcuts that were allowed to regrow. Compared to interior trees, those on edges were typically shorter, retained branches lower on their boles, oriented their first branches more towards the edge, and produced more asymmetrical crowns with the long axis extending into the opening; these trends were greater on south- than north-facing edges and along permanent than temporary edges. Contrary to expectations, there were no edge effects on total basal area, dead tree densities, proportions of sand pine trees with leaning trunks, directions of lean, or angles of lean. Instead of an edge effect, most trees leaned southwesterly, which seems related to the northeastern origin of prevailing winds and wind gusts.

Vigor of Java Plum Seedlings, in the Presence and Absence of Mucilage Submitted to Different Substrates

Java plum (Syzygium cumini L. Skeels) originates from Asia and has adapted very well to soil conditions and climate in Brazil, becoming spontaneous in the Northeast region. Still, there is no large commercial production in the country, since information related to planting, plant management, post-harvest management, and fruit processing is limited and vague. The production of quality seedlings depends on several factors, and the composition of the substrates is a factor of great importance, because the germination of the seeds, the beginning of the roots and the rooting are directly linked to the constitution of the substrate. The experiment was conducted in a greenhouse at the Federal Institute of Education, Science and Technology of the Tocantins, at a city of Gurupi/TO. For this, Java plum seeds were used directly removed from the fruits, which were collected in the same period. The substrates used were: Washed Sand; Black Soil; Black Soil + Worm Humus + Commercial Substrate and Commercial Substrate + Washed Sand + Pine Bark, in the presence and absence of mucilage. The highest values of root length and length of shoot, in the presence and absence of mucilage, were obtained in the substrates of BS (10 and 13 cm) (8.7 and 9.3 cm), BS + WH + CS (9.3 and 12.4 cm) (8.2 and 9.5 cm) and CS + WS + PB (9 and 11 cm) (8.6 and 10.6 cm), respectively. Regarding the first emergency count and seedling emergence, once again the CS + WS + PB (20 and 56.2%) (51.2 and 90%), in the presence and absence of mucilage, respectively. It was concluded that the removal of the mucilage in Java plum seeds provided better performance in all substratum and the commercial substrate + washed sand + pine bark provided greater viability and vigor.

Substrates and fertilizations in the initial growth of the desert rose

The desert rose (Adenium obesum) has been highlighted in the internal market, however there are not many studies related to its demands regarding its nutrition and substrates. The aim of this study was to evaluate the effect of different fertilizations and its interactions with different substrates in the initial growth of the desert rose. The seedlings of desert rose with 60 days have been potted transplanted with a capacity of 0.415 L, filled with two kinds of substrates: sand + coconut fiber and sand + composted pine powder. Four different fertilization managements have been done: without fertilization, application of the Hoagland & Arnon nutrient solution; application of NH3 NO4 at 590 g L-1 of nitrogen (N); and the application of the Hoagland & Arnon nutrient solution modified through the addition of NH3 NO4 , increasing the concentration of N to 800 g L-1. The solutions have been applied biweekly adding 50 mL per pot. The experiment has been entirely randomized in a 2x4 factorial design, with 10 repetitions. After 150 days from the beginning of the fertilizations the phytometrical parameters evaluated were: height of the shoot; diameter of the basal caudex; number of shoots; dry mass of the roots, caudex and leaves; and determination of the levels and accumulation of macronutrients in the shoot, and the pH and electrical conductivity of the substrates. The evaluated data have been submitted to an analysis of variance and the Tukey test compared through the test at 5% of error probability. For all the evaluated parameters, when the composted pine mixture was used, the seedlings showed a higher development compared to coconut fiber mixture. The seedlings had a better performance with the modified Hoagland solution for height, number of shoots, caudex diameter and leaf dry mass in both substrates. The use of the sand + pine powder (1:1 v v-1) and the fertilization with Hoagland & Arnon solution combined with the NH3 NO4 solution provided a better initial growth on the desert rose.

Effects of Soil Temperature during Fire on Seed Survival in Florida Sand Pine Scrub

Soil temperatures recorded with thermocouples and temperature-sensitive paints were quantified during Florida sand pine scrub prescribed fires at Ocala National Forest and Archbold Biological Station in May 1993. Thermocouples and glass petri dishes painted with temperature-sensitive paints and containing seeds ofEriogonum floridanumwere placed at 0 cm and 2 cm depth, and in vegetated and open microsites. Maximum temperatures were higher and peak temperature durations shorter at 0 cm than at 2 cm depth. Temperatures did not differ between microsites during the Ocala fire, but were higher in open microsites during the Archbold fire, probably due to combustion of well-aerated litter. Maximum temperatures of petri dishes were lower than those of adjacent thermocouples due to time required to melt paints. AllEriogonumseeds recovered from petri dishes after the Archbold fire failed to germinate. Germination was quantified forEriogonum floridanumandGarberia heterophyllaseeds heated to C and C under laboratory conditions. Seeds failed to germinate at C, while germination was similar to controls for seeds exposed to C. Results from this study suggest that small-scale spatial variation temperatures at the soil surface during fires is essential for seed survival and subsequent post-fire recruitment.

Regeneration of Mugwort (Artemisia vulgaris) from Rhizome Sections in Sand, Pine Bark, and Soil Substrates

Regenerative potential of mugwort (Artemisia vulgaris L.) rhizome sections has not been quantified when rhizomes are transplanted into substrates encountered in landscapes and nursery fields, container nurseries, or propagation beds. Mugwort regeneration in pine bark, sand, and soil substrates was analyzed by rhizome color, length, and the presence or absence of a leaf scale. Color of rhizomes, which darken with time, did not account for differences in growth among treatments. Contrary to previous research, 85, 78, and 69% of 2 cm-long rhizome sections produced both roots and shoots when grown in pine bark, sand, and soil substrates, respectively, during 45-day trials. Slightly less than 31% of rhizome fragments 0.5 cm long without a leaf scale produced both roots and shoots in soil. Though fewer rhizomes survived in soil, root and shoot fresh weights were greater than in pine bark and sand. When rhizome sections included a leaf scale, survival, fresh weights of roots and shoots, shoot height, leaf number and root lengths were greater, regardless of substrate type. Root initials emerged both adjacent to leaf scales and in the internode between leaf scales. Shoot emergence preceded root emergence from rhizome sections.