Academic literature on the topic 'Shade tolerance in trees][Tree growth'

Tropical cloud forests play a fundamental role in the hydrological cycle of mountain watersheds having the largest biodiversity per unit area. In Venezuela, cloud forests are subject to intense deforestation and fragmentation by farming and cattle-ranching causing soil erosion, water cycle alteration, and biodiversity loss. Reforestation projects used exotic species as Pines and Eucalyptus, native species were rarely planted by lacking knowledge on species requirements and management. We report the performance of 25 native cloud forest species differing in shade-tolerance, planted in mixed assemblies on degraded areas. Tree survival and the individual tree variables: total height, root-collar diameter, tree-slenderness, and crown-ratio were evaluated at 1, 2, 4.5 and 7 years-old. Data was analyzed with a repeated measures analysis of variance mixed model considering species shade-tolerance, light intensity at planting and age as explanatory factors. Survival was over 80%. Shade-intolerant species displayed faster height and root-collar diameter growth. Shade-tolerant species had larger crown ratios due to persistence of lower branches; whereas, shade-intolerant showed signs of crown recession at age 7. Slenderness values from age 4.5 were indicative of good trees stability and health across treatments. The positive results have motivated landowners to establish native species plantations in critical areas with our support.

Plants exhibit an extraordinary range of sizes and generation times, from single-celled algae with body sizes of the order of 5 mm and generation times of the order of 1 day, to massive forest trees more than 50 m tall that can live for over 1000 years. Diatoms and trees have the virtue of being easy to count, so it is natural to seek to model the dynamics of changes in numbers. On the other hand, many herbaceous perennials (like clonal herbs or turf-forming grasses) are difficult or impossible to count, and for these plants it is natural to model the dynamics of fluctuation in biomass or proportional space occupancy. The theory of plant population dynamics is linked to the rest of plant biology through a series of fundamental trade-offs, reflecting the fact that individual plants are constrained in what they can do. There are important trade-offs in reproduction because a plant could produce many small seeds or a few large seeds, but it is not an option to produce many large seeds. Other trade-offs involve investment decisions: for instance a plant can invest in growth or defence and this leads to a trade-off between competitive ability and palatability to herbivores. Alternatively, high growth rate in full sun may trade-off against a high death rate in low light (the cost of shade tolerance). An important set of trade-offs involve competing demands for resource capture. Thus a plant could invest in its root system to forage for phosphorus, or in its shoot system to forage for light, but it cannot maximise investment in competitive ability for light and soil nutrients. Finally, there is an important trade-off between competition and colonization because good dispersers tend to be inferior competitors; this is exemplified by the r-K continuum where colonizers (r strategists) have a set of traits like rapid generation time, small seeds, wind dispersal, and high light requirements, whereas late successional species (K strategists) tend to live longer, produce fewer, larger seeds, and to have more shade-tolerant, slowergrowing juveniles. Underpinning the theory of plant population dynamics is the invasion criterion, which states that all persistent populations must exhibit the tendency to increase when rare.

Adaptation of the local tree species to recent environmental conditions rather often is found to be very low even when it affects tree health integrally with air pollutants, and surface ozone. The aim of the study was to quantify the relationships between environmental factors, annual stem basal area increment and crown defoliation of Scots pine trees located in the north-eastern part of Lithuania. The obtained data revealed that Scots pine is the most sensitive species to environmental changes. Its reaction to both negative and favorable environmental factors was best expressed, what indicate