technically speaking, the tree cover is continually replenished with wind, water and cycles of nature. mammals and birds also plant the seeds by adding compost via their poop.
the question then becomes - where do the trees go? I feel there is a different mix of many local factors. The empty land is not always empty and gets visited by human influence in different times of year -
a. Overgrazing - say a village with 50% tree cover could support 500 livestock. Now the tree cover has come down to 10% but livestock is at 300. So it isnt just that they have too many animals, but too little productive capture of sun, water and hence too little rejuvenation and capacity of commons.
b. Household cooking- communities are forced to over harvest when commons forest cover and unfenced accessibly goes down. Twigs and dry leaves which should stay and accumulate get used as tinder.
c. Industrial fuel - the empty patches are visited by local biofuel mafia when ready to harvest and all big trees get chopped. A scary amount of informal industries use common wood for furnaces. When this happens legally, a panchayat generates revenue for state, but generally the local village boss person will have a few vehicles transporting commons timber for cashflow.
d. Forest fires - can be good in certain contexts to accelarate nutrient production. But monoculture canopy + biodiversity loss + invasive species make fires more common and also human induced. The community gets fresher greencover as fire rapidly releases calcium, magnesium and other nutrients which would have otherwise taken a year of slow decomposition. This gives a higher short term return but kills off many saplings.
e. Economics and operations of farmer - in small land holding sizes of fields, it makes more economic sense to do a monoculture. A single variety of seed, planting, caretaking and harvest keeps operations simple and farmer has to spend fewer days on field which they use to earn cash by wages(say 150 days vs 250 days in natural farming).
f. Yeild - Annuals under a good year also give 3-5x yeild over perennials and don’t wax and wane alternate years like tree based plantations do. A mature tree’s growth rates also fall as it spends more on self maintenance. Short season crops are monsoon dependent but also fastest to yeild in short term.
g. Neighborhood conflict on shade - on acre sized fields, unless it is culturally acceptable to have trees on bunds of field, the neighbouring farmers . Have heard of neighborhood conflicts because of perceived, and perhaps a little real highjacking of sunlight.
On the second part - about water recharge narrative building to incentivise tree growing.
a. Technical feasibility wise, i feel groundwater recharge of truly depleted areas needs fairly intensive earthworks. Building a swale, basin, recharge pit leads to a 20% loss of agricultural land. For 100 small fields they might build an interconnected series of recharge ponds.
b. Economic feasibility wise - another challenge is that if a farmer builds such a pit, it helps the downstream neighbour more, while the cost centre remains for upstream farmer to figure out.
Older govt, social, taxation systems accounted for this need. For ex- arthashastra would enforce a mandatory minimum number of water bodies be built with mandatory participation - labour, oxen, money else fines. A part of the harvest also remains within this watershed and gets saved under next year’s maintenance fund with the local govt rep.
Today this money goes up to PM, is supposed to come down via CM, DM, … but often doesn’t come back again to the place that was the watershed and the pond that is the real productivity engine.
Or it comes to pond thanks to current govt’s focus on water but often becomes cement, plastic or steel like a walking pathway with benches and signboards giving ₹100, ₹10, ₹1 to the PM, CM, DM value chains. The core of problem - desilting, bunding, upsrtream watershed management if ignored for few years - fill the pond. Technology helps the village forget.
Culture, but has been requesting everyone to come to their neighbourhood ponds pre monsoon with their fruits(prasada) and seeds. The coconuts were kept on water filled pots in last month pooja so now they have sprouted. Now that the pond has gotten trees and labour for free, in few years they will start giving for free.