Seasonal changes in dry matter yield from Karst pastures as influenced by morphoclimatic features

Pastures are strongly affected by local environmental variables in terms of their species richness, plant composition and herbage production. A multi-site monitoring study was conducted over three years to investigate the influence of morphoclimatic factors on the seasonal variations in dry matter (DM) yield from Karst pastures. Seven sites located on the Italian and Slovenian Karst regions were investigated that differed in terms of their geological and geomorphological features, as well as their soil types. At each site, the daily DM yield (kg ha-1 d-1) was determined using Corral-Fenlon method which permits to simulate herbage utilization from grazing herds. The morphoclimatic features were also analysed, with the aim to evaluate the link between seasonal DM yield and geomorphological and environmental factors. Generalized non-linear mixed models were built to study the observed seasonal variations in DM yield, using day of the year (DOY), growing degree days (GDD), and cumulative rainfall. Furthermore, environmental descriptors were included in the model in order to evaluate their effects on DM yield. The seasonal variations in yield showed two growing periods (spring and late summer), which were described by Gaussian curves. For the spring growing period, the model improved when the interaction between soil granulometry and growing degree days corresponding to the curve peak was taken into account. This confirms the influence of soil type and air temperature on pasture yield. For the late summer growing period, the interaction between the sand classes and the number of rainy days from the beginning of the period to the peak of the curve improved the model. The curve parameters of our models are correlated with environmental descriptors depending on the lithology and particle size of soils. The results are essential for the optimization of pasture management and avoiding degradation due to over- or under-grazing

Measuring Stolons and Rhizomes of Turfgrasses Using a Digital Image Analysis System

Length and diameter of stolons or rhizomes are usually measured using simple rulers and calipers. This procedure is slow and laborious, so it is often used on a limited number of stolons or rhizomes. For this reason, these traits are limited in their use for morphological characterization of plants. The use of digital image analysis software technology may overcome measurement errors due to human mistakes, which tend to increase as the number and size of samples also increase. The protocol can be used for any kind of crop but is particularly suitable for forage or grasses, where plants are small and numerous. Turf samples consist of aboveground biomass and an upper soil layer to the depth of maximum rhizome development, depending on the species of interest. In studies, samples are washed from the soil, and stolons/rhizomes are cleaned by hand before analysis by digital image analysis software. The samples are further dried in a laboratory heating oven to measure dry weight; therefore, for each sample, the resultant data are total length, total dry weight, and average diameter. Scanned images can be corrected before analysis by excluding visible extraneous parts, such as remaining roots or leaves not removed with the cleaning process. Indeed, these fragments normally have much smaller diameters than stolons or rhizomes, so they can be easily excluded from analysis by fixing the minimum diameter below which objects are not considered. Stolon or rhizome density per unit area can then be calculated based on sample size. The advantage of this method is quick and efficient measurement of the length and average diameter of large sample numbers of stolons or rhizomes

Plant species loss due to forest succession in Alpine pastures depends on site conditions and observation scale

n/

Base temperatures affect accuracy of growing degree day model to predict emergence of bermudagrasses

AbstractThe germination of bermudagrass [Cynodon dactylon (L.) Pers.] under different temperature regimes has been extensively investigated, but a discrepancy remains between laboratory studies and field results. Thermal requirements calculated in growing degree days (GDD) have been found to differ within the same species depending on the location of the study. The accumulation of GDD may vary under different thermal conditions from seeding to seedling emergence and could depend on TBASE used in the calculation. The most widely used TBASE for bermudagrass is 5 °C. However, laboratory studies have suggested that a base temperature of 15 °C would more accurately predict seedling emergence. In this field study, we investigated the effect of using TBASE 5 °C vs. TBASE 15 °C on the estimation of GDD required by bermudagrass to emerge. Ten cultivars were seeded in northeastern Italy on three dates between 10 March and the end of April in 2013 and 2014. Number of emerged seedlings was counted weekly and soil temperature at 1‐cm depth was recorded significant differences in seedling emergence between bermudagrass genotypes were found. Results demonstrated that the algorithm used to calculate GDD is strongly influenced by the TBASE used and to include a TBASE of 15 °C explains germination and emergence more accurately than a TBASE of 5 °C

St. Augustinegrass accessions planted in northern, central and southern Italy: Growth and morphological traits during establishment

The use of warm season turfgrasses is a consolidated trend in the climatic transition zone of Mediterranean countries, in particular St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) begins to be widespread in warm coastal areas. However, little is known about the performance of the different cultivars of this species in southern Europe. In 2016-2017 a trial was carried out in three locations in Italy, Padova, Pisa. and Palermo, located in the north, center and south of the country respectively. Four cultivars (Floratine, Captiva, Sapphire, Pahnetto) and five ecotypes (CeRTES 201, CeRTES 202, CeRTES 203, CeRTES 204, CeRTES 205) were compared in terms of their growth characteristics and morphological traits during establishment. The results highlighted that stolon growth was significantly affected by the location, as well as green colour retention. Stolon growth rate, internode length and internode volume and turf quality were, however, significantly determined by the accession effect. The quality of the ecotypes was also in some cases comparable to that of the cultivars. In Padova, winterkill occurred in most of the accessions, while in Pisa and Palermo, all the entries survived. In conclusion. St. Augustinegrass is suitable for turf use in the central and southern coastal area of Italy

St. Augustinegrass accessions planted in northern, central and southern Italy: Growth and morphological traits during establishment

The use of warm season turfgrasses is a consolidated trend in the climatic transition zone of Mediterranean countries, in particular St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) begins to be widespread in warm coastal areas. However, little is known about the performance of the different cultivars of this species in southern Europe. In 2016-2017 a trial was carried out in three locations in Italy, Padova, Pisa, and Palermo, located in the north, center and south of the country respectively. Four cultivars (Floratine, Captiva, Sapphire, Palmetto) and five ecotypes (CeRTES 201, CeRTES 202, CeRTES 203, CeRTES 204, CeRTES 205) were compared in terms of their growth characteristics and morphological traits during establishment. The results highlighted that stolon growth was significantly affected by the location, as well as green colour retention. Stolon growth rate, internode length and internode volume and turf quality were, however, significantly determined by the accession effect. The quality of the ecotypes was also in some cases comparable to that of the cultivars. In Padova, winterkill occurred in most of the accessions while in Pisa and Palermo, all the entries survived. In conclusion, St. Augustinegrass is suitable for turf use in the central and southern coastal area of Italy

Effects of wood establishment on plant biodiversity and herbage production of mountain pastures

In the past sixty years, the Southern Alps have undergone a tremendous and likely unprecedented change in land-use due to land abandonment in mountain regions. This phenomenon causes a turn of mountain grasslands to forests through the process of natural succession. Vegetation relevés in eight pastures under forest succession in the Italian Alps were collected at different percentage of wood cover. Moreover, in four of the eight sites, herbage samples were collected at different wood cover levels. In addition, in one site (characterised by Nardus grassland habitat) core samples were collected in order to study root characteristics. Species richness, botanical composition, dry matter production and contents, and root characteristics were taken into account in order to analyze the effect of wood cover on plant diversity, herbage yield and quality, and soil stability. The effect on specie richness due to this process is different among sites because of differences in environmental factors and human activities. In general species richness decreased with increasing wood cover, and the reduction was more relevant in sites at low altitude. In some sites the effect of reforestation on plant species richness showed a slight increase at low percentage of wood cover followed by a gradual decrease, while in the others the effect displayed a monotonic decrease. Modelling with a generalized linear mixed model suggested that mean annual temperature was the primary determinant of the functional relationship. Differences among sites were not found when botanical composition, and in particular Bray dissimilarity index, was taken into account. A reduction of dry matter yield was noted in most of the studied sites. Forest succession affected herbage quality decreasing it starting from low percentage of wood cover because of changes in crude protein and fibrous contents. When root characteristics were analyzed, root length density and average diameter declined at 75% of wood cover increasing the risk of soil erosion. Based on this results, mountain areas with low relevance for dairy production grazing should be encouraged for preserving both biodiversity and the stability of habitat. The strong effect of temperature on the loss of species richness suggests that the risk increases with lower altitude and stronger exposition towards South. The maintenance of low percentage of wood cover is useful for the habitat ecological value. On the contrary, in mountain areas where dairy production grazing is relevant, the management should be assessed for excluding wood establishment on the grazing surface.Negli ultimi sessant’anni, nell’ambiente alpino ed in particolare nelle Alpi italiane, si è assistito ad un importante e senza precedenti cambiamento d’uso del suolo, dovuto all’abbandono delle zone montane. Questo fenomeno ha causato un avanzamento del bosco su prati e pascoli attraverso un processo naturale di riforestazione. Per questo studio sono stati eseguiti rilievi floristici in otto pascoli montani delle Alpi italiane, soggetti ad avanzamento del bosco. Inoltre, in quattro di questi otto siti sono stati raccolti campioni di foraggio per la determinazione della produttività e della qualità della fitomassa. Infine, in un sito, caratterizzato dalla presenza di habitat a Nardus stricta, sono state raccolte carote di terreno per la caratterizzazione della componente ipogea. In tutti i casi i rilievi e i campionamenti sono stati eseguiti a percentuali crescenti di copertura arboreo-arbustiva. Sono stati considerati i seguenti parametri: numero di specie, composizione botanica, produzione e composizione chimica della sostanza secca nonché densità e diametro medio della radici a diversi livelli di profondità nel terreno, in modo da analizzare l’effetto della copertura arboreo-arbustiva su diversità vegetazionale, produzione e qualità del pascolo e stabilità del suolo. L’effetto sul numero di specie causato dall’avanzamento del bosco è risultato diverso tra i siti a causa delle differenze che intercorrono nei fattori ambientali e nelle attività antropiche. In generale si è assistito ad una diminuzione del numero di specie per effetto dell’avanzamento del bosco, in alcuni siti però è stato osservato un leggero aumento per bassi valori di copertura arboreo-arbustiva. La diminuzione del numero di specie è stata più marcata nei siti ad altitudine inferiore. Usando un modello lineare misto generalizzato, è stato riscontrato che le temperature medie annue sono uno dei fattori che meglio spiegano la diversa relazione tra i siti. L’analisi della composizione floristica mediante l’indice di Bray, ha evidenziato un comportamento simile tra i siti. Nella maggior parte dei siti analizzati si è riscontrata una diminuzione della produzione in sostanza secca per effetto della copertura arborea. Inoltre, già a partire da basse percentuali di copertura arboreo-arbustiva, è stata osservata una diminuzione della qualità della fitomassa prodotta dal pascolo, per effetto di una diminuzione del contenuto di proteina grezza ed un aumento delle fibre. Relativamente alle radici, si è osservato come la densità radicale in lunghezza e il diametro medio diminuissero drasticamente a percentuali di copertura arboreo-arbustiva del 75%, aumentando verosimilmente il rischio di erosione del suolo. Sulla base di questi risultati possiamo dire che nelle regioni montane, laddove la vocazione produttiva (in termini di produzione casearia) è poco rilevante, andrebbe incoraggiato il mantenimento di questi habitat a vantaggio della biodiversità e della stabilità del suolo. Come visto in questo studio, l’effetto della temperatura media annua sulla diminuzione del numero di specie, suggerisce che il rischio di perdita di biodiversità aumenta ad altitudine minore e in aree esposte a sud. Il mantenimento di basse percentuali di alberi o arbusti può essere utile per conservare il valore naturalistico di questo habitat. Al contrario, nelle zone dove la vocazione casearia del pascolo è prevalente, la gestione dovrebbe essere tale da mantenere le superfici a pascolo completamente libere da alberi e arbusti