Effect of ink disease on chestnut litterfall production and on nutrient budgets over a 3-year period

The objective of this work was to study the effect of ink disease on the amount of litterfall produced and on litter N, P, K, Ca, Mg and S budgets, by comparing adjacent diseased and healthy chestnut groves, with different soil and weather conditions and degree of ink disease. The litter was collected between April 1994 and March 1997 in three locations in Northern Portugal. Ink disease decreased the total amount of litter produced by an average of 64%, mainly due to significantly lower fruit, bur and inflorescence production. On average, fruit production decreased by 76%, burs by 73% and inflorescences by 54%. In the affected (A) plots leaves were the main litter component while in the healthy (NA) plots fruit made the biggest contribution to the total. This pattern of litter production affected the amount of nutrients released by the trees in the litterfall and, consequently, the nutrient balances. In A plots the biggest proportion of nutrients released by the trees was in leaves while in NA plots it was in fruit, except for Ca and Mg which are the nutrients least present. So, only these nutrient budgets were higher in NA plots then in the A plots. However, in general, the high amounts of N, P and K exported by fruits did not negatively affect their nutrient budgets as the input from all the other litter components was higher than fruit output.